Direct and Residual Effect of Phosphate rock on growth and yield of wheat under Old Himalayan Piedmont Plain soils.

Md.Nurul Huda Al Mamun

Abstract

A study was conducted to observe the direct and residual effects of phosphate rock (PR) on the growth and yield of wheat (cv.Kanchan) during rabi season of 2004-2005 under Old Himalayan Piedmont Plain (AEZ 1) soil at Wheat Research Sub-center, Dinazpur. The experiment was designed with four treatments and laid out in a Randomized Complete Block Design (RCBD) with four replications of each treatment. The treatment combinations were T_1: control (0 kg P ha-¹), T₂: PR (26 kg P ha-¹),T₃ :TSP(26 kg P ha-¹) and T₄: PR(210 kg P ha-¹ was applied in previous crop to cover 6 succeeding crops). Dry matter yield at panicle initiation (PI) stage was significantly varied with different treatments. The yield contributing characters such as the effective tillers hill^-1, grains panicles^-1, varied significantly with P treatments. The highest grain yield (3.52 t ha^-1) and straw yield (5.24 t ha^-1) in T₃ treatment. The yield due to different treatments ranked in the order of T₃>T₄>T₂>T₁. The economic analysis demonstrated that the highest net benefit of Tk. 29,698 ha^-1 was observed in T₃ treatment followed by Tk. 25,610 ha^-1 and Tk. 13,943 ha^-1 in T₄ and T₂ treatments, respectively. The highest net benefit was obtained in T₃ treatment due to higher grain and straw yields but T₄ treatment had shown better performance over T_{2 .}

Key words: Residual effect, Phosphate rock, Growth and Yield, Old Himalayan Piedmont Plain

1. Introduction:

Wheat (Triticum aestivum L.) is the most important cereal crop and ranks first both in acreage and production of the world (UNDP and FAO,1999).It has been established as the second most important staple food crop after rice in Bangladesh (Razzaque and Hossain,1999).Bangladesh produces 12,53,000 metric tons of wheat per annum from 15,86,000 acres of land (BBS,2004).The cereal crop production like wheat should be increased to meet the demand of the escalating population of Bangladesh, where an individual requires 454 g cereal food (BARI,2004).The Soil and climate of Bangladesh is favorable in winter for wheat production but the average yield of wheat in this country is quite low as compared to that of many wheat growing countries of the world. Improper management of fertilizers is one of the major causes of low production because fertilizer plays an important role in augmenting yield of wheat. Phosphorus is the second key plant nutrient needed in adequate quantity in available source of growth, reproduction, yield and quantity of crop. The phosphorus content of Bangladesh soils is being depleted day by day due to crop removal particularly in intensive culture. So, application of phosphatic fertilizers is recommended for all soils and crops in Bangladesh to obtain better yield (BRAC, 2005).Triple super phosphate (TSP) is the main source of phosphorus, where single super phosphate (SSP) is water soluble and newly introduced phosphetic fertilizer in Bangladesh and its popularity has been increasing day by day. Rock phosphate (PR) is another source of phosphorus. It is the cheapest and economic source of phosphorus (Hoffland, 1991) which is not being used in the crop field due to its insolubility.The direct application of finely ground rock phosphate (PR) may be an attractive alternative to the use of more expensive soluble P-fertilizer for certain crops and soils (Hammond et al., 1986).But in Bangladesh, a little research work has been done in this aspect. Keeping this in this view, the present research has been set up to compare the effect of direct application of PR and TSP on growth and yield of wheat, to study the response of wheat as affected by residual effects of high rate of PR applied in preceding T.aman crop and to compare economic benefits of PR with TSP as the source of P on wheat.

2. Materials and Methods

2.1. Site description

The field experiment was carried out with wheat (cv.Kanchan) grown in sequence after aman rice under some selected treatments. The experiment was set up at Wheat Research Sub-center, Dinazpur under Old Himalayan Piedmont Plain (AEZ 1) agro-ecological region of Bangladesh during the Rabi season of 2004-2005.The farm belongs to the general soil type Non-calcareous Dark Grey Floodplain soil under Sonatal series.

2.2. Treatments and design

The experiment was laid out in a Randomized Complete Block Design (RCBD) with 4 replications. Each block was sub-divided into 4 unit plots. The total number of plots was 16(4X4) and the unit plot size was 8mX5m.The spacing between blocks was 1m and between plots 0.3m.There were four treatments consisting of TSP and two rates of rock phosphate (PR) and a control. The treatment combinations were T_1: control (0 kg P ha-¹), T_2: PR (26 kg P ha-¹), T₃: TSP (26 kg P ha-¹) and T₄: PR (210 kg P ha-¹ was applied in previous crop to cover 6 succeeding crops).

2.3. Fertilizer application, transplanting and intercultural operations

The experimental field was first opened on 20 days before sowing with the help of power tiller and cross-ploughed 6 times. All kinds of weeds and residues of previous crop were removed from the field. The plant nutrients like Nitrogen, Phosphorus, Potassium, Sulphur and Boron were used in the research field as 100kgN ha^-1,26kgP ha^-1,33kgK ha^-1,20kg S ha^-1and 1kg B ha^-1 respectably. All fertilizers except N were applied to the soil during final land preparation. Nitrogen as urea was applied in two times; firstly 2/3 of urea was applied during final land preparation. Remaining 1/3 urea was applied as top dressing at the time of 21 days after emergence of seedlings. The seed was shown on November 20, 2004 and seed rate was 120 kg ha^-1as recommended by BARI (2003).Line to line distance was 20 cm with continuous distribution of seeds in the lines in each plot. Inter cultural operations such as irrigation, weeding and pest control etc. were done as and when required.

2.4. Harvesting and data collection

At the spike emergence stage and at harvest the plant samples were collected from each plot. Ten hills per plot were collected randomly for the determination of dry matter yield and nutrient analysis. The crop was harvested at full maturity on 14 March, 2005.Sun dried weight of both grain and straw were recorded plot-wise for each treatment.

2.5. Chemical analysis of soil and plant samples

The initial soil sample was collected before land preparation from 0-15 cm and analyzing for both physical and chemical properties in the Laboratory of the Department of Soil Science, Bangladesh Agricultural University, Mymensingh. Particle size analysis of soil was done by Hydrometer method (Gee and Bauder, 1986). Soil pH was measured with the help of glass electrode pH meter using soil water suspension of 1:2:5(Jackson, 1962).Organic carbon in soil was determined by wet oxidation method ( Walkley and Black,1934).Cation exchange capacity (CEC) of soil was determined by sodium saturation method as outlined by Chapman (1965). Total nitrogen of soil was estimated by micro kjeldhal method (Bremner and Mulvaney, 1982).Available soil phosphorus was measured by Olsen method (Olsen and Sommers, 1982).Exchangeable potassium was determined by using flame photometer (Black, 1965) and available sulphur was determined by turbidimetric method. The collected grain and straw samples from each plot were dried in an oven at 65⁰C for 48 hours after which they were ground by a grinding mill. Later the ground samples were sieved through a 20- mesh sieve. The prepared samples were then chemically analyzed for N, P, K and S following diacid digestion procedure (Jones and Case, 1990; Watson and Issac, 1990).The analysis of variance for crop characters and also for the nutrient elements of plant samples were done following the F-test. Mean comparisons of the treatments were made following the Duncan’s Multiple Range Test (DMRT).

3. Results and Discussion

3.1 Growth of wheat plants at panicle initiation (PI) stage

All the treatments differed significantly in dry matter yield development at PI stage of growth of wheat plant. Maximum dry matter production (2.49t ha^-1) was obtained in T₃ treatment, which was 36.5% increase over control (Table 1). T₃ and T₄ treatments were statistically similar. The minimum dry matter production (1.82 t ha-1), was observed in control.

Yield contributing characters

3.2. Plant height

Plant height, one of the agronomic characteristics, was found to be statistically insignificant in treatments used in all the experiment. The maximum plant height (107.05 cm) was attained in the treatment T₄ and the minimum plant height (104.27 cm) was obtained in T₁ treatment (Table 2).

3.3. Effective tillers hill^-1

Maximum number of effective tillers (3.25 hill^-1) was found in T₃ treatment (Table 2).TSP treatment showed better result over PR treatment having the same P rate (26 kg P ha^-1). The minimum number of effective tillers (2.30hill^-1) was found in control. Zaman et al.(1997) found increase the effective tillers hill^-1 over control due to P application on wheat crop.

3.4. Panicle length

Panicle length was highest in T₃ treatment (10.17 cm) (Table 2). TSP treatment showed better result over PR having the same P rate (26 kg P ha^-1).The lowest panicle length (7.12cm) was found in T₁ treatment. The second highest panicle length was found in T₄ (210 kg P ha^-1) was applied in previous crop treatment (9.12 cm).

3.5. Sterile spikelets spike^-1

Maximum numbers of sterile spikelets (4.35) were found in control (T₁) treatment, which was statistically similar to PR treatment. However, the percentage of sterile spikelets spike^-1 ranged from 4.8 to 12.3 % (Table 2).The lowest number of sterile spikelets spike^-1(1.92) was found in T₃.

3.6. Grains spike^-1

The highest number of grains spike^-1 (36.90) was recorded in T₃ (26 kg P ha^-1) treatment which was statistically similar to T₄ treatment (210 kg P ha^-1 was applied in previous crop).However, the percentage of grains spike^-1 varied from 87.6 to 95.1 (Table 2).The lowest number of grains spike^-1 (30.75) was obtained in control.

3.7. 1000-grain weight

The weighed of 1000-grain varied from 46.30 to 48.44g.The highest value was found in T₃ treatment and the lowest value was observed in T₁ treatment. TSP treatment had better effect compared to PR having same rate of P (26 kg P ha^-1).However, 1000-grain weight did not produce any significant difference between the treatments.

3.8 Grain yield

The recoded grain yield due to different treatments of P ranged from 2.06 to 3.52 t ha^-1 which differed significantly (Table 3).The maximum grain yield (3.52 t ha^-1) increase was obtained by T₃(26 kg P ha^-1) treatment, which showed an increase of 70.8% over control. The second highest grain yield increase was obtained in T₄ treatment (3.12 t ha^-1), which the third highest grain yield was recorded in PR (T₂) treatment (2.50 t ha^-1). The treatments T_2, T₃ and T₄ were statistically similar. The minimum grain yield was (2.06 t ha^-1) noted in control treatment. Chowdhury and Mian (1978) reported that the grain yield of wheat increased with increasing levels of P from either TSP or PR.

3.9. Straw yield

Straw yield of wheat (cv.Kanchan) was also significantly influenced due to different treatments. The maximum straw yield (5.24 t ha^-1) was obtained in T₃ treatment, which showed an increase of 74.0% over control. The treatments T₃ and T₄ were statistically similar. The lowest straw yield (3.01) was recorded in control. However, TSP treatment showed significant straw yield.

Table 1: Effects of different treatments on dry matter yield at booting stage of wheat at Wheat Research Sub-centre, Dinajpur

Treatments	Dry matter yield(t ha-1)	Increase over control (%)
T1 Control (0 kg P ha-1)	1.82c	-
T2 PR (26 kg P ha-1)	2.05b	12.5
T3TSP(26 kg P ha-1)	2.49a	36.5
T4 PR(210 kg P ha-1*)	2.47a	32.6
SE (±)	0.0542	-
CV (%)	4.35	-

*210 kg P ha^-1 was applied in previous crop to cover six succeeding crops.SE (±) = Standard error of means

Figures in a column having common letters do not differ significantly at 5% level of significance by DMRT.

Table 2: Effects of different treatments on yield contributing characters of wheat (cv.Kanchan) at Wheat Research Sub-centre, Dinajpur

Treatments	Plant Height (cm)	Effective tiller hill-1(No.)	Panicle length(cm)	Sterile spikelets spike-1(No.)	Sterile spikelets spike-1(%)	Grains spike-1(No.)	Grains spike-1(%)	1000-grains weight (g)
T1	104.27	2.30c	8.26c	4.35a	12.3	30.75b	87.6	46.30
T2	104.60	2.55bc	9.10ab	2.85b	7.3	35.78a	92.6	46.80
T3	105.78	3.25a	10.17a	1.90c	4.8	36.90a	95.1	48.44
T4 *	107.05	3.05ab	9.12ab	2.55bc	6.8	36.05a	93.1	46.98
SE (±)	NS	10.41	0.3487	0.1812	-	1.0026	-	NS
CV(%)	2.07	0.1451	7.61	12.45	-	5.75	-	3.22

*210 kg P ha^-1 was applied in previous crop to cover six succeeding crops.SE (±) = Standard error of means

Figures in a column having common letters do not differ significantly at 5% level of significance by DMRT.

Table 3: Effects of different treatments on grain and straw yields of wheat (cv.Kanchan) at Wheat Research Sub-centre, Dinajpur

Treatments	Grain		Straw
	Grain yield t ha-1	Increased over control (%)	Straw yield t ha-1	Increased over control (%)
T1	2.06d	-	3.01c	-
T2	2.50c	21.3	4.12b	36.8
T3	3.52a	70.8	5.24a	74.0
T4 *	3.12b	51.4	5.06a	65.1
SE (±)	0.0642	-	0.129	-
CV (%)	4.82	-	5.73	-

*210 kg P ha^-1 was applied in previous crop to cover six succeeding crops.SE (±) = Standard error of means

Figures in a column having common letters do not differ significantly at 5% level of significance by DMRT

14. Economic analysis

The analysis was done in order to find out the most profitable treatment based on cost- benefit of various treatments. Net benefit was calculated by subtracting the total input cost from the gross field profit. Gross field profit was calculated as the total market value of grain and straw of wheat. The input cost was calculated as the total market value of fertilizer and others material and non- material cost. The data were shown in Table 4. The results of economic analysis of wheat (cv.Kanchan) demonstrated that highest net benefit of Tk. 29,698 ha^-1 was obtained in T₃ treatment followed by Tk. 25,610, Tk.13, 943 and Tk. 7,654 kg ha^-1 in T₄, T₂ and control treatments, respectively. The farmers will preferably choose any of these treatments which can give higher net benefit with relatively a lower variable cost.

Table 4. Cost-benefit analysis of wheat (cv.Kanchan) during rabi season 2004-05 at Wheat Research Sub-centre, Dinajpur

Treatments	Total output (kg ha-1)		Gross field income (Tk ha-1)			Total production cost (Tk ha-1)	Net income(Tk ha-1)	Net benefit due to addition of PR(26 kg P ha-1)over control (Tk ha-1)	Net benefit due to addition of TSP (26 kg P ha-1)over T2 (Tk ha-1)	Net benefit due to addition of PR(210 kg P ha-1)over T3 (Tk ha-1)
	Grain	Straw	Grain	Straw	Total
T1	2060	3010	30900	3010	33910	26256	7654	-	-	-
T2	2500	4125	37500	4125	41620	27677	13943	6289	-	-
T3	3520	5240	52800	5240	58040	28342	29698	-	15755	-
T4 *	3120	5066	46800	5066	51866	26256	25610	-	-	4088

*210 kg P ha^-1 was applied in previous crop to cover six succeeding crops. Production cost other than fertilizer and PR remain same in all treatments. Grain and straw as per current market price

Output cost Input cost

Grain@ Tk.15 kg^-1 a. Material cost b. Non-material cost

Straw@ Tk. 1.00 kg^-1 PR @Tk. 7.00 kg^-1 Labor @ Tk.15550.00 ha^-1

TSP@ Tk.16 Kg^-1 Ploughing @ Tk.1760.00 ha^-1

Urea @ Tk.6.00 Kg^-1

MOP @ TK.16.00 Kg^-1

Gypsum@ Tk. 5.00 Kg^-1

Boric acid @ Tk. 120.00 Kg^-1

Irrigation@ Tk.1800.00 ha^-1

Pesticide @Tk.1400.00 ha^-1

Seed Tk.2100.00 ha^-1

Conclusion: It may be concluded that the use of rock phosphate will entirely be a new source of P fertilizer to be used in the country. TSP had better performance over PR having same rate of P (26 kg P ha¹) and (210 kg P ha^-1 was applied in previous crop) which was treated as residual effect of PR. Treatment T₄ showed comparatively better performance than T₂ because of its (PR) low solubility. Although PR bear some toxic substances in soil but its low price and high residual effect of cropping system could be and added factor for easy acceptance of P fertilizer compared to other phosphatic fertilizers. The effect of TSP on growth and yield of wheat was better than the direct application of PR. The residual effects of high rate of PR applied in preceding T.aman crop had shown better performance than the PR which was used in present wheat crop. The highest economic benefit was found in TSP compare to PR.

References

Agarwal,M.M. 1976. Effect of fertilizer treatments on the grain quality of wheat. Indian J. Agril. Res. 10(3): 185-188.

Agarwal,M.M. 1978. Effect of N,P and K on yield, uptake and quality of rice. Indian J. Agril. Res. 12: 35-38.

Ahmed,M. 1993.A study on the Joint effect of Rock Phosphate and TSP on the Yield and Quality of Transplanted aman Rice (Nizershail). An M.Sc.(Ag) thesis. Session 1987-88. Dept. of Agril. Chemistry, BAU,Mymensingh.

BARC.2005.Fertilizer Recommendation Guide. Soils Pub.43, Bangladesh Agric.Res.Council, Farmgate, Dhaka.

BARI.2004.Hand book on Agro-Technology,3^rd Edition, Bangladesh Agricultural Research Institute, Gazipur, Dhaka.

BBS.2004,Monthly Statistical Bulletin Bangladesh (December 2004).Bangladesh Bureau of Statistics, Statistics Division, Ministry of Planning, Government of the People’s Republic of Bangladesh.

Black,C.A 1965.Methods of soil analysis part 1 and 2.Amer.Soc.Agron.Inc.Pub. Madison,Winsconsin,USA.

Bremner,J.M and Mulvaney, C.S.1982.Total Nitrogen, In Methods of Soil Analysis. Miller,R.H. and Xeeny,D.R. 1982.Amer.Soc.Agron.Inc.Madi.Wis.USA.pp.595-622.

Chapman,H.D.1965. Cation Exchange capacity. In Methods of Soil Analysis. C.A. Black Ed.pp. 891-901.Amer.Soc.Agron.,Inc.,Madison,Wisconsin.

Chowdhury,S.U. and Mian,M.H.1978.Effect of superphosphate on the yield of wheat and rice on acid soil of Nagaland and nutrient content of grain. Indian Soc.Soil Sci.32(2):299-302.

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Gee,G.W. and Bauder,J.W.1986. Particle- size Analysis.In Methods of Soil Analysis, Part-1 (2^nd edition).A. Klute ed.,pp.383-411. Amer. Soc. Agron., Inc. and Soil Science Soc. Amer.,Inc. Madison, Wisconsin.

Hammond,L.L.; Chien, S.H and Mokwunye, A.U. 1986. Agronomic value of unacidulated and partially acidulated phosphate Rocks Indigenous to the tropics. Adv. Agron. 40:89-140.

Hoffland,E. 1991. Mobilization of rock phosphate by rape (Brassica napus L.). Ph.D. Thesis, Wageningen Agricutural University, Wageningen, The Netherlands, p. 93.

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Jones,Jr.J.B. and Case, V.W. 1990.Sampling,handling and analyzing plant tissue samples. In: Soil testing and plant analysis, 3^rd edition, SSSA Book series 3,(ed.) W.S. Westermaan, Soil Science Society of America,Madision,WI,USA,389-427 pp.

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Olsen, S.R.; Cole, C.V.; Watanabe, F.S. and Dean, L.A. 1954. Estimation of available phosphorus in soils by extraction with sodium bicarbonate.U.S. Dept. Agric.Cire. p.929.

Razzaque, M.A. and Hossain,A.B.S. 1999.The wheat for development programme Bangladesh. In: Proc. Wheat for non- traditional warm area D.A. Saunders e., UNDP/CYMMYT.

Walkley and Black, C.A. 1934. An examination of Degtjareff method for determining soil organic matter and proposed modification for the chromic acid titration method. Soil Sci.,37:29-38.

Watson,M.E. and Isaac,R.A.1990. Analytical instruments for soil and plant analysis. In: Soil testing and plant analysis, 3^rd edition.SSSA Book series 3,(ed.) W.L.Westermaan, Soil Science Society of America,Madision,WI,USA,691-740 pp.

Zaman,S.K.; Razzaque, M.A.; Karim,S.M.R. and Bhuiyan,N.I. 1997. Rice response to phosphorus in wetland soil. Pakistan J.Sci. Indus.Res. 38(11-12): 438-440.

Effect of Phosphate rock on soil characteristics and nutrient uptake of wheat under Old Brahmaputra Floodplain soils.

Md.Nurul Huda Al Mamun and Md.Safinur Rahman


Abstract

A study was conducted to observe the direct and residual effects of phosphate rock (PR) on the growth and yield of wheat (cv.Kanchan) during rabi season of 2004-2005 under Old Brahmaputra Floodplain soil at Bangladesh Agricultural University Farm, Mymensingh. The experiment was designed with four treatments and laid out in a Randomized Complete Block Design (RCBD) with four replications of each treatment. The treatment combinations were T1: control (0 kg P ha-1),T2 : PR(26 kg P ha-1),T3 :TSP(26 kg P ha-1) and T4: PR(210 kg P ha-1 was applied in previous crop to cover 6 succeeding crops). Nutrient Content and uptake by wheat plant varied significantly with P treatments. The yield due to different treatments ranked in the order of T3>T4>T2>T1.The maximum N,P,K and S contents as well as uptake by wheat plant in grain and straw were recorded in T3 treatment. The Characteristics of the post harvest soil as influenced due to different treatments. The highest nutrient content of post harvest soil like pH, Organic matter, P and K were found in T3 treatment.

1. Introduction

Bangladesh is agrarian country, where agriculture is the single largest sector. Economic development of the country basically rests on agricultural development. It accounts for almost above one – third (35%) of Gross Domestic product (GDP) and provides employment for two-thirds of the labor force (Sarker and Islam, 2001).Wheat (Triticum aestivum L.) is the most important cereal crop and ranks third both in acreage and production of the world (UNDP and FAO,2008).It has been established as the second most important staple food crop after rice in Bangladesh (Razzaque and Hossain,1999).Bangladesh produces 12,53,000 metric tons of wheat per annum from 15,86,000 acres of land (BBS,2004).The cereal crop production like wheat should be increased to meet the demand of the escalating population of Bangladesh, where an individual requires 454 g cereal food (BARI,2004).The Soil and climate of Bangladesh is favorable in winter for wheat production but the average yield of wheat in this country is quite low as compared to that of many wheat growing countries of the world. Improper management of fertilizers is one of the major causes of low production because fertilizer plays an important role in augmenting yield of wheat. Phosphorus is the second key plant nutrient needed in adequate quantity in available source of growth, reproduction, yield and quantity of crop. The phosphorus content of Bangladesh soils is being depleted day by day due to crop removal particularly in intensive culture. So, application of phosphatic fertilizers is recommended for all soils and crops in Bangladesh to obtain better yield (BRAC, 2005).Triple super phosphate (TSP) is the main source of phosphorus, where single super phosphate (SSP) is water soluble and newly introduced phosphetic fertilizer in Bangladesh and its popularity has been increasing day by day. Rock phosphate (PR) is another source of phosphorus. It is the cheapest and economic source of phosphorus (Hoffland, 1991) which is not being used in the crop field due to its insolubility. The direct application of finely ground rock phosphate (PR) may be an attractive alternative to the use of more expensive soluble P-fertilizer for certain crops and soils (Hammond et al., 1986).But in Bangladesh, a little research work has been done in this aspect. Keeping this in this view, the present research has been set up to compare the effect of direct application of PR and TSP on growth and yield of wheat, to study the response of wheat as affected by residual effects of high rate of PR applied in preceding T.aman crop and to compare economic benefits of PR with TSP as the source of P on wheat.

2. Materials and Methods
2.1. Site description

The field experiment was carried out with wheat (cv.Kanchan) grown in sequence after aman rice under some selected treatments. The experiment was set up at Soil Science field Laboratory of Bangladesh Agricultural University, Mymensingh under Old Brahmaputra Floodplain (AEZ 9) agro-ecological region of Bangladesh during the Rabi season of 2004-2005.The farm belongs to the general soil type Non-calcareous Dark Grey Floodplain soil under Sonatal series.

2.2. Treatments and design

The experiment was laid out in a Randomized Complete Block Design (RCBD) with 4 replications. Each block was sub-divided into 4 unit plots. The total number of plots was 16(4X4) and the unit plot size was 8mX5m.The spacing between blocks was 1m and between plots 0.3m.There were four treatments consisting of TSP and two rates of rock phosphate (PR) and a control. The treatment combinations were T1: control (0 kg P ha-1), T2: PR (26 kg P ha-1), T3: TSP (26 kg P ha-1) and T4: PR (210 kg P ha-1 was applied in previous crop to cover 6 succeeding crops).

2.3. Fertilizer application, transplanting and intercultural operations

The experimental field was first opened on 20 days before sowing with the help of power tiller and cross-ploughed 6 times. All kinds of weeds and residues of previous crop were removed from the field. The plant nutrients like Nitrogen, Phosphorus, Potassium, Sulphur and Boron were used in the research field as 100kgN ha-1,26kgP ha-1,33kgK ha-1,20kg S ha-1and 1kg B ha-1 respectably. All fertilizers except N were applied to the soil during final land preparation. Nitrogen as urea was applied in two times; firstly 2/3 of urea was applied during final land preparation. Remaining 1/3 urea was applied as top dressing at the time of 21 days after emergence of seedlings. The seed was shown on November 20, 2004 and seed rate was 120 kg ha-1as recommended by BARI (2003).Line to line distance was 20 cm with continuous distribution of seeds in the lines in each plot. Inter cultural operations such as irrigation, weeding and pest control etc. were done as and when required.

2.4. Harvesting and data collection

At the spike emergence stage and at harvest the plant samples were collected from each plot. Ten hills per plot were collected randomly for the determination of dry matter yield and nutrient analysis. The crop was harvested at full maturity on 14 March, 2005.Sun dried weight of both grain and straw were recorded plot-wise for each treatment.

2.5. Chemical analysis of soil and plant samples

The initial soil sample was collected before land preparation from 0-15 cm and analyzing for both physical and chemical properties in the Laboratory of the Department of Soil Science, Bangladesh Agricultural University, Mymensingh. Particle size analysis of soil was done by Hydrometer method (Gee and Bauder, 1986). Soil pH was measured with the help of glass electrode pH meter using soil water suspension of 1:2:5(Jackson, 1962).Organic carbon in soil was determined by wet oxidation method ( Walkley and Black,1934).Cation exchange capacity (CEC) of soil was determined by sodium saturation method as outlined by Chapman (1965). Total nitrogen of soil was estimated by micro kjeldhal method (Bremner and Mulvaney, 1982).Available soil phosphorus was measured by Olsen method (Olsen and Sommers, 1982).Exchangeable potassium was determined by using flame photometer (Black, 1965) and available sulphur was determined by turbidimetric method. The collected grain and straw samples from each plot were dried in an oven at 650C for 48 hours after which they were ground by a grinding mill. Later the ground samples were sieved through a 20- mesh sieve. The prepared samples were then chemically analyzed for N, P, K and S following diacid digestion procedure (Jones and Case, 1990; Watson and Issac, 1990).The analysis of variance for crop characters and also for the nutrient elements of plant samples were done following the F-test. Mean comparisons of the treatments were made following the Duncan’s Multiple Test (DMRT).

3. Results and Discussion
Nutrient Content and uptake at panicle initiation stage
3.1 Nitrogen content and uptake by wheat plant

Results in Table 1.showed that the N content in wheat plant at PI stage significantly influenced by different treatments. The maximum N content (1.26%) was obtained in T3 treatment while control treatment showed the m inimum N content (0.90%).But the treatments T3 and T4 were statistically identical. Nitrogen uptake by wheat (cv Kanchan) also varied significantly. The highest N uptake (28.35 kg ha-1) was obtained in T3 treatment and the minimum value (13.68 kg ha-1) was noted in control treatment.

3.2 Phosphorus content and uptake by wheat plant

The P content in wheat plant at PI stage was significantly influenced by different treatments .The P content ranged from 0.085 to 0.283%.The minimum content was obtained in the control and the highest P content was recorded in T3 treatment. A significant increase in P uptake by wheat plant was also obtained due to different treatment (Table 1).T3 treatment showed the maximum P uptake (6.37 kg ha-1) and control treatment showed the minimum P uptake (1.29 kg ha-1).P applied in the form of TSP was found to have better effect over PR having same rate of P application (26 kg P ha-1).

3.3 K content and uptake by wheat

The K content in wheat (cv.Kanchan) at panicle initiation stage was significantly influenced by different treatments and ranged from 1.09 to 1.28% .The highest value was obtained in T3 treatment, and control treatment showed the lowest K content. K uptake by wheat plant responded significantly due to different treatments ranged from 16.52 to 28.80 kg ha-1.The highest K uptake (28.80 kg ha-1) was indicated in T3 treatment and lowest value (16.52 kg ha-1) was noted in control.

3.4. S content and uptake by wheat plant

Result that S content increased significantly by different treatments. S content in wheat plant varied from 0.140 to 0.164%. The maximum value was noted in the treatment T3 and the control treatment showed minimum S content. S uptake by wheat plant also responded significantly due to different treatments. The highest S uptake (3.69 kg ha-1) was obtained in T3 treatment and the lowest value (2.13 kg ha-1) was found in control and the S uptake ranged from 2.13 to 3.69 kg ha-1. The treatments T2 and T4 were significantly identical.

Nutrient content and uptake in grain and straw
3.5. Nitrogen content in grain and straw

Application of PR and TSP exerted positive effect on the N content in grain. The concentration of N in grain ranged from 1.90 to 2.10% . The maximum N content was recorded in T3 treatment and the lowest N content was found in control treatment (T1) which was statistically identical to T2 and T4 treatments. On the other hand, N content in straw ranged from 0.442 to 0.641% and the maximum concentration of N content was obtained in the T3.TSP had shown better effect over PR (26 kg P ha-1) and T4(210 kg P ha-1) treatments.

3.6 .Nitrogen uptake in grain and straw

N uptake in grain and straw was influenced significantly due to application of PR and TSP.N uptake by grain ranged from 38.95 to 65.10 kg ha-1.The maximum N uptake was noted in T3 treatment and the lowest N uptake was recorded in control .The second highest N uptake was found in T4 treatment.Similarly, in case of straw, the highest N uptake (35.51 kg ha-1) was observed in T3 treatment and lowest N uptake (12.92 kg ha-1) was noted in control. The second highest N uptake (28.65 kg ha-1) by straw of wheat was found in T4 treatment.

Total N uptake ranged from 51.87 to 100.61 kg ha-1. The maximum total N uptake was found in T3 treatment and the minimum total N uptake was recorded in control. The second highest N uptake was observed in T4 treatment, which was treated as residual effect of PR. It may be explained that P fertilization increased the N content and uptake in cereals irrespective of different sources. Munson (1986) described that P enhanced N content as well as uptake in grain because of improved metabolism and utilization of other elements.

3.7. P content in grain and straw

The P content in grain and straw was significantly affected by the different treatments. The contents of phosphorus in grain varied from 0.233 to 0.301 % (Table 3).The maximum P content was observed in TSP treatment followed T4(0.29%) and T2 (0.284%).The minimum P content was observed in control treatment. The highest P content in straw was attained in T3 (0.159%) followed by T4 (0.143%) and T2 (0.101%) and the minimum P content was found in control treatment. However, in both cases TSP has shown better effect over PR having same rate of P. On the other case, TSP also had shown better performance over residual effect of PR in T4 treatment.

3.8. P uptake in grain and straw

Like P content, P uptake by grain and straw was influenced significantly due to different treatments. However, maximum P uptake was recorded in T3 (9.33 kg ha-1) treatment from TSP source and minimum P uptake (4.92 kg ha-1) was in control. Similar trend was also noticed in case of total P uptake. The total P uptake varied from 6.36 to 18.13 kg ha-1.Significant increase in P content as well as uptake with the application of P fertilizer was in corroboration with the findings of Agarwal (1976) and Hammond et al. (1986).

3.9. K content in grain and straw

The K content in grain ranged from 0.395 to 0.462% . The maximum K content was recorded in T2 treatment which was statistically identical with T3 (0.447%) and T4 (0.410%).The control treatment noted minimum K content (0.395%). In case of straw, K content also varied due to different treatments. All the treatments increased the K content significantly over control. The maximum K content (1.48%) in straw was found in T3 treatment which was statistically identical with T4 treatment and the minimum K content (1.29%) was obtained in control treatment.

3.10. K uptake in grain and straw

K uptake by grain ranged from 8.09 to 13.85 kg ha-1.The maximum K uptake was recorded in T3 treatment followed by T4 (11.68 kg ha-1) and then by T2 (10.00 kg ha-1).The lowest K uptake was found in control treatment. The same trend was observed in case of K uptake by straw. The highest K uptake was observed in T3 (81.99 kg ha-1) treatment followed by T4 (77.47 kg ha-1) and T2 (48.87 kg ha-1).The lowest K uptake (37.66 kg ha-1) was recorded in control. Results in Table 4. showed that total K uptake varied significantly (from 45.75 to 95.84 kg ha-1) due to different treatments. The maximum K uptake (95.84 kg ha-1) was recorded in T3 treatment and the lowest K uptake was observed in control. The second highest total K uptake was found in T4 treatment, where 210 kg P was applied in previous crop to cover six crops. P fertilizer appeared to have synergistic effect on the K content in grain and straw. Similar observation of increase in K content and uptake with the application of phosphetic fertilizers were reported by may investigators (Ararwal, 1978; Reddy and Bhardwaz, 1983).

3.11. S content in grain and straw

Application of PR and TSP exerted positive effect on S content in grain of wheat. The content of S in grain ranged from 0.269 to 0.328% . The highest S content was observed in T3 treatment which was statistically similar to that was observed in T4 (0.315%) treatment. The lowest S content was found in control treatment, but it was identical with T2. In case straw, the maximum S content (0.124%) was recorded in T3 treatment which was statistically identical to that of T2 and T4. The control treatment obtained minimum S control (0.098%).

3.12. S uptake in grain and straw

Results indicated that S uptake by grain was also significantly influenced by different treatments. The range of S uptake observed in grain was 5.51 to 10.16 kg ha-1.The maximum S uptake (10.16 kg ha-1) was recorded in T3 treatment and the lowest value (5.51 kg ha-1) was recorded in control. The second highest value (8.97 kg ha-1) was found in T4 treatment, which treated as residual effect of PR. In case of straw, the maximum S uptake was recorded in T3 treatment which was statistically identical to that of T4 treatment. The control treatment obtained minimum S uptake and the range was 2.86 to 6.86 kg ha-1. Application of PR and TSP had significant effect of total S uptake .The highest total S uptake (17.02 kg ha-1) was found in T3 treatment and the lowest total S uptake was observed in control treatment (8.37 kg ha-1). Works of different investigators (Joshi and seth, 1975; Ahmed, 1993) also revealed that the P fertilization increased S content and uptake of wheat grain.

3.13. Characteristics of post harvest soils

Result showed a marked variation on the soil pH, soil organic matter, N, P, K and S of the initial soil values. pH values of the post harvest soils ranged from 6.72 to 6.92,whereas the initial soil pH value ranged from 6.61 to 6.69. The highest pH value (6.92) was recorded in T3 treatment. The lowest pH value (6.72) was recorded in T1 treatment. The organic matter content of the post harvest soil range varied from 2.18 to 2.29% whereas the initial soil organic matter range varied from 2.21 to 2.34 %( Table 6). The maximum organic matter content (2.29%) of post harvest soil was observed in T3 treatment and the minimum organic matter content (2.18%) was obtained in control treatment. The total N content of the post harvest soil varied from 0.147 to 0.154% , where the initial soil total N varied from 0.145 to 0.149%. The highest total N was observed in control treatment and the lowest total N was found in T2 and T3 treatment. The variation of total N content value among the treatments was insignificant. Application of PR and TSP exerted significant effect on the available P in post harvest soil. The available P content in post harvest soil varied from 10.49 to 16.50 ppm, where the initial soil available P content range varied from 10.37 to 16.20 ppm. The highest available P content was recorded in the treatment T3 (16.50ppm) which was statistically significant with T4 treatment (16.25 ppm). The lowest available P content was found in control treatment. The variation of exchangeable K content value of post harvest among treatment was insignificant. The exchangeable K content of post harvest soils ranged from 0.126 to 0.135 cmol kg-1 whereas the initial soil exchangeable K content range varied from 0.125 to 0.131 cmol kg-1.The highest exchangeable K content was observed in T3 treatment (0.135 cmol kg-1) and the lowest exchangeable K content was found in control treatment (0.126 cmol kg-1).Available S content of post harvest soils influenced significantly due to different treatments . The maximum S content (14.55 ppm) was observed in control and the minimum available S content (13.37ppm) was observed in T3 treatment. The available S content of initial soil ranged from 12.06 to 14.51 ppm.

Conclusion: It can be concluded that the use of rock phosphate will entirely be a new source of P fertilizer to be used in the country. TSP had better performance over PR having same rate of P (26 kg P ha1) and (210 kg P ha-1 was applied in previous crop) which was treated as residual effect of PR. Treatment T4 showed comparatively better performance than T2 because of its (PR) low solubility. Although PR bear some toxic substances in soil but its low price and high residual effect of cropping system could be and added factor for easy acceptance of P fertilizer compared to other phosphatic fertilizers. The effect of TSP on nutrient contents as well as uptake by wheat plant in grain and straw was better than the direct application of PR. The residual effects of high rate of PR applied in preceding T.aman crop had shown better performance than the PR which was used in present wheat crop.

References
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Agarwal,M.M. 1978. Effect of N,P and K on yield,uptake and quality of rice. Indian J. Agril. Res. 12: 35-38.
Ahmed,M. 1993.A study on the Joint effect of Rock Phosphate and TSP on the Yield and Quality of Transplanted aman Rice (Nizershail). An M.Sc.(Ag) thesis. Session 1987-88. Dept. of Agril. Chemistry, BAU,Mymensingh.
BARC.2005. Fertilizer Recommendation Guide. Soils Pub.43, Bangladesh Agric.Res.Council, Farmgate, Dhaka.
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Bremner,J.M and Mulvaney, C.S.1982.Total Nitrogen, In Methods of Soil Analysis. Miller,R.H. and Xeeny,D.R. 1982.Amer.Soc.Agron.Inc.Madi.Wis.USA.pp.595-622.
Chapman,H.D.1965. Cation Exchange capacity. In Methods of Soil Analysis. C.A. Black Ed.pp. 891-901.Amer.Soc.Agron.,Inc.,Madison,Wisconsin.
Chowdhury,S.U. and Mian,M.H.1978.Effect of superphosphate on the yield of wheat and rice on acid soil of Nagaland and nutrient content of grain. Indian Soc.Soil Sci.32(2):299-302.
FAO and UNDP.2008. Land Respond Appraisal of Bangladesh for Agricultural Development. Report 1 Agro-ecological Regions of Bangladesh. Food and Agricultural Organization and United Nations Development Programme.pp.212-221.
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Hammond,L.L.; Chien, S.H and Mokwunye, A.U. 1986. Agronomic value of unacidulated and partially acidulated phosphate Rocks Indigenous to the tropics. Adv. Agron. 40:89-140.
Hoffland,E. 1991. Mobilization of rock phosphate by rape (Brassica napus L.). Ph.D. Thesis, Wageningen Agricutural University, Wageningen, The Netherlands, p. 93.
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Jones,Jr.J.B. and Case, V.W. 1990.Sampling,handling and analyzing plant tissue samples. In: Soil testing and plant analysis, 3rd edition, SSSA Book series 3,(ed.) W.S. Westermaan, Soil Science Society of America,Madision,WI,USA,389-427 pp.
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Munson, R.D. 1986. Phosphorus and crop quality. Phosphorus for Agriculture; a situation analysis. Potash and Phosph.Inst.p.69-73.
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Razzaque, M.A. and Hossain,A.B.S. 1999.The wheat for development programme Bangladesh. In: Proc. Wheat for non- traditional warm area D.A. Saunders e., UNDP/CYMMYT.
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Walkley and Black, C.A. 1934. An examination of Degtjareff method for determining soil organic matter and proposed modification for the chromic acid titration method. Soil Sci.,37:29-38.
Watson,M.E. and Isaac,R.A.1990. Analytical instruments for soil and plant analysis. In: Soil testing and plant analysis, 3rd edition.SSSA Book series 3,(ed.) W.L.Westermaan, Soil Science Society of America,Madision,WI,USA,691-740 pp.
Zaman,S.K.; Razzaque, M.A.; Karim,S.M.R. and Bhuiyan,N.I. 1997. Rice response to phosphorus in wetland soil. Pakistan J.Sci. Indus.Res. 38(11-12): 438-440.

Use of Soil Resource in Bangladesh:Problem and Prospective

Md.Nurul Huda Al Mamun


INTRODUCTION
Bangladesh is the largest deltaic floodplain in the world with a total area of 14570 km2 of which 88892 km2 is occupied by major rivers and estuaries. The great delta is flat throughout and stretch from near the foothill of the Himalayas mountain in the north to a southern and irregular deltaic coastline that faces the bay of Bengal. The country is mostly surround by India except for a short (about 200 km) southeastern frontier with Myanmar. She lies between 20034″ and 26038″ north latitude, and 88001″ and 92041″ longitude. Bangladesh is one of the densely populated countries in the world with about 150 million people. The population density is around 974 people per km2 with annual growth rate of 1.54 percent. Agriculture is the life force of her economy. The country has been a food deficit area for long time and has about 8.2 million hectares of cultivated land with average cropping intensity of about 190 per cent (BBS 2008). Soil is the most important natural resource. The majority of the country’s soils are alluvial. Hill and terrace soils represent only 20 per cent of the country and 8-10 per cent of the cultivable land. Agro ecologically the country has been divided into thirty regions.

The rainfall ranges from 1500 mm in the North West to 5000 mm in the northeast. The rainfall along with depth and duration of flooding remain the critical factors for agriculture in the country. The critical aspects of rainfall in relation to the use of land for agriculture relate to the uncertainty of the onset and departure of the monsoon as well as the occurrence of drought, Bangladesh is really very lucky in having a hyper thermos temperature regime where agriculture production is possible all though the year. Bangladesh has more than 60% of the land area under agricultural use, against only 12% for the world. The country is really at odds in maintaining ecological balance on one hand and maintaining self sufficiency in food production for its burgeoning population on the other. Very few agrarian societies in the world have willfully employed such a high percentage of their land area under cultivation.
Bangladesh comprises hills, terraces and alluvial plains. The major portion of the Bengal Basin of the Sindhu-Ganges depression lies in Bangladesh. Recently formed delta and alluvial plains of the Ganges, Brahmaputra and Meghna rivers are the most extensive area of cropping practices (cropping intensity 180%, BBS 2009). However, most of the area suffers from a variable extent of soil and land constraints and natural hazards. The south-western part of Bangladesh mainly comprising Ganges river and tidal alluvial plains has a lower cropping intensity of 134% (BBS, 2009) along with severe constraints due to certain unfavorable soil and land characteristics and natural disasters like drought, flood, cyclonic storm surges, tornadoes, etc. The ingression of soil and water salinity from the Bay of Bengal causes adverse affect on cropping practices and other uses of land resource. This region thus needs special attention for its development and to mitigate constraints to use potentials. Keeping in view feed the hungry millions no area is separable for intensive use according to its potentials with adoption of suitable measures to overcome the constraints.


What is Soil
Soil is a natural body consisting of layers (soil horizons) of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics. It is composed of particles of broken rock that have been altered by chemical and environmental processes that include weathering and erosion. Soil differs from its parent rock due to interactions between the lithosphere, hydrosphere, atmosphere, and the biosphere. It is a mixture of mineral and organic constituents that are in solid, gaseous and aqueous states. Soil particles pack loosely, forming a soil structure filled with pore spaces. These pores contain soil solution (liquid) and air (gas).
This has been possible for the existence of the proverbially futile soils on the few vast flood plains that are annually replenished by siltation during flooding. Over 60% percentage of the population in Bangladesh depends direct or indirectly upon agriculture, while nearly 22% of the gross national product comes from this sector.

Bangladesh Soil
The major part of Bangladesh is on the delta formed by the three major rivers brahmaputra, ganges and meghna. These rivers and many of the country's other minor rivers originate outside the national boundary of the country and make up the Ganges-Brahmaputra-Meghna river system. The system drains a basin of some 1.76 million sq km and carry not only snowmelt water from the himalayas but also runoff water from some of the highest rainfall areas of the world. Over millennia, the sediments carried by the huge discharges of these rivers have built a broad delta, forming most of the large area of Bangladesh and the submerged delta-plain in the bay of bengal. These huge sediments are the major sources of formation of 80% soils of the country. The remaining 20% of soils have been formed in Tertiary and Quaternary sediments of hills (12 %) and in uplifted pleistocene terrace (8%).

Fig. 1 General Soil Map of Bangladesh
Soil Resource of Bangladesh
Bangladesh though a small country, has surprisingly a wide range of soils. About 576 soil series have been identified which ranges from juvenile alluvium or manmade soil material deposits at one extreme to old, deeply weathered, red soils at the other with variation kinds of hydomorphic and drainage characteristics in between these soil series have been grouped in to 21 general soil types (Brammer, 1984). The general soil type is a local level of classification system designated in a very broad land of generalization for use of general purpose. This system provides an overview of the soil condition of the whole country or of a region within the country. The general principles taken to classify the soils are that they are first divided into broad categories. 1. The floodplains soils 2. The terrace sinlase 3. The hill soils. Although physiographically Bangladesh appears to be a relationally simple landmark, as many as 22 physiographic units has been identified. (FAO-UNDP,1988). The physiographic units are the identification of the land formation and the origin of the soil materials.
The tertiary hills belonging to the district of Chittagong,Chittagong hill tracts,Sylhet, the edge of the Garo hills in Mymensingh and Lalmai hills of Comilla occupy 12% of the country. They are composed mainly of unconsolidated and some consolidated rocks and sediments of mostly miocne and pliocne geological periods. The soils are mainly coarse textured and being located in a high rainfall area and are intensely leached and have developed strong acidity. The soils inherently have low fertility status and are degraded in many places for various reason. The reasons are surface erosion, jhum cultivation and deforestation shifting cultivation is practiced locally by tribal people living there.The Pleistocene terrace include mainly the Modhupur tract in greater Dhaka, Tangail and Mymensingh district and the Barind tract of greater Rajshahi, Bogra, Rangpur and Dinazpur districts and the Akhaura terrace of B baria district, which together occupy 8% area of the country. The soils of these tracts stand on the high land above the floodplain and have good external drainage. Because of origin of soils are mainly clay loam/clayey texture, contain numerous ferruginous concretions are relatively rich in free iron and aluminium oxides and have high phosphate fixing capacity.
The Gangetic alluvium is calcareous and may contain <15%>
COSTRAINT OF USE OF SOIL RESOURCE
Throughout human history, soil has been repeatedly ruined and destroyed. This is highly dangerous to a civilization, because soil is an essential resource that is useful in many ways. Some societies have even collapsed due to mistreatment of their soil resources, so modern people must be cautious to avoid a similar fate.
They have many limitations they are:
Soil Erosion
Soil erodibility is the inherent liability of the soil to erode. This is a function of the properties of the soil itself especially soil structure and texture (SRDI 1998). Erosivity is a term applied to rainfall referring to inherent characteristics of rainfall in terms of its potential to cause erosion.
Soil degradation
Soil degradation refers to the decline in the productive capacity of the soil. Used broadly it may subsume soil erosion, however more usually reference is made to soil erosion and degradation as two distinct but related phenomena. Soil degradation may be caused by preferential soil erosion where the most productive fraction of the soil is lost leaving the less fertile part. This may occur without visible or measurable physical loss, for example of soil depth, and can only be determined through comparative soil analysis.
Infiltration
Infiltration rate (also mistakenly known as percolation) is the rate at which water enters into the soil. When the rate of water supply (rainfall) exceeds the infiltration rate then runoff occurs and flows over the soil surface as overland flow, a critical parameter in soil erosion by water. Nutrient mining and land quality
It is essential to maintain an optimum fertility land in the soils for attaining sustainable agriculture production. In a low input agriculture the gradual net loss of nutrients from soils is everyday phenomenon. Agriculture in Bangladesh is practiced on moderately fertile soils of the without application of adequate quantity’s of farmland manures and chemical fertilizer. As a result, yield have started to become stagnant or even declining in many areas. But in some cases the decline in land productivity has been offset by higher fertilizer application. The decrease of yields has been estimated to be around one percent per year and in the more adversely affected areas if it is higher than that. There has been steady increase in the yields of HYV rice. Nutrient mining in Bangladesh soils has been noted as a serious and widespread problem ( Karim and Iqbal, 2001) estimated a total loss of 1.25 million tons of Nitrogen, phosphorus, potassium from the agriculture land of Bangladesh every year.
Environmental impact of Agriculture
The indiscriminate use of lands, imbalanced use of fertilizers, non-judicious use of agrochemicals and very low land-man ratio has created a threat to the agriculture of Bangladesh. To meet the over-growing needs of an extremely outsized population, the country's natural resource base is rapidly being outstripped by human induced environmental degradation, especially due to poor management of agricultural lands. Some of them are briefly enumerated below.

Loss of organic matter and nutrient depletion

The intensive cultivation of HYV rice without organic recycling and rapid mineralization is important factor, causing depletion of organic matter and other plant nutrient & thereby disturbed the agro-ecosystem of the country.

Dystrification

In parts of coastal tidal floodplain, clearing of mangrove vegetation and subsequent drainage improvement resulted in the formation of Acid Sulphate Soils with extreme acidity associated with aluminum toxicity and phosphate fixation. These soils also remain saline even after empoldering, and thus land productivity eventually declines.

Water logging
Most of the agricultural lands in Khulna region occupy the lowlying areas and covers a total area of about 1.3 M ha. These lands are inundated to variable depths during monsoon season. Farmers generally used to grow a single crop of rice occasionally followed by some rabi crops locally where possible. But the crop yield was too low which were often used to be damaged by early and or late floods.

Lowering groundwater and Salinization

With the introduction of modern varieties of rice groundwater extraction has largely been started during 1970s. It is reported that the continued extraction of groundwater and withdrawal of fresh
water in the upper riparian areas has resulted in lowering of groundwater and upconing of saline water respectively in coastal areas.

Loss of productive function

In floodplain areas soils are mined for brick making, earth filling and land raising from the fertile crop fields for the development of rural infrastructure. Land productivity is reduced locally by peat mining particularly in the Khulna-Gopalganj peat basin. Salinity problem, already serious, could be further aggravated due to global warming and sea level rise with implication for drinking water (especially in Khulna area), agricultural products and industrial installations. Area of high salinity may increase from existing 13% to 32%. Use of agrochemical, insecticides pesticides etc. has a serious implication on land and soil quality and a subsequent destruction of ecosystem.




Arsenic and heavy metal pollution
Cases of arsenic poisoning were reported in certain parts of the country due to increase concentration of arsenic compound (>0.05ppm) particularly in the over-drawn aquifers. Locally drainage improvement of almost perennially wet peat in the peat basin causes limited subsidence. Excess drawdown of groundwater also may cause land subsidence in certain less stable areas.

Problem soil
Problem Soils impose a severe limitation on successful crop production due to the unfavourable effects of certain chemical and/or physical properties of soils. acid sulphate soils, saline and alkali soils, peat soils, soils with nutrient toxicity (very minor area) and nutrient deficiency are examples of chemical soil problems while steeply sloping soils, coarse textured soils, shallow soils, poorly drained soils, heavy textured soils and soils with ploughpan are included in soils with physical problems.
Low Soil Fertility Status

Although Bangladesh is a small country, it has wide variety and complexity of soils at short distances due to a diverse nature of physiography, parent materials, lands, and hydrology and drainage conditions. Due to intensive cropping to grow more food, continuous changes are taking place in the soil fertility status due to organic matter depletion, nutrient deficiencies, drainage impedance/water logging followed by degradation of soil physical and chemical properties as well as soil salinity/acidity. The fertility status of Bangladesh soils is extremely variable. Most of the soils are depleted and are in urgent need of replenishment with organic manure and fertilizers if projected crop production target is to be obtained.

Beside this there are many limitations are as follows:
Annual flooding
Seasonal drought
Tropical cyclones
Cold wave
River eroding








Prospective of soil resource

Fertilizer Recommendation


Fertilizer recommendation for single crops and cropping patterns are usually made by following the guidelines clearly stated in “The National Fertilizer Recommendation Guide” which is revised and published from time to time by the Bangladesh Agricultural Research Council in consultation with NARS scientists engaged in soil fertility and fertilizer management research activities. Upazila Soil Use Guide published and updated by SRDI from time to time is also a useful guide for site-specific fertilizer recommendation. Each guide has at least 100-150 site-specific information on soils nutrient status, topography, hydrology, vegetation and drought. Fertilizer recommendations are usually made on the basis of soil fertility classes; yield goals and farmers’ management ability. For high yield goal fertilizer recommendation, one should have site-specific information on nutrient status of soils as well as the crops.


Balanced Fertilization


Balanced fertilization is the key to successful crop production and maintenance of good soil health. It is important to see how close nutrient addition and removal by crops match with each other. According to current statistics, the farmers of Bangladesh use 215 kg nutrients (N: 149 kg, P2O5: 37 kg, K2O: 22 kg and S + Zn + B + others: 7) ha/year from chemical fertilizers, while the estimated removal is around 280 -350 kg/ha. From organic and natural sources about 50-70 kg nutrients are added to the soil system every year. One nutrient balance study made by DAE-SFFP (2002) from a typical Boro- Fallow – T. Aman cropping pattern.


Soil Testing Facilities

For using balanced fertilization, Soil Resource Development Institute (SRDI) is providing soil testing facilities for farmers as well as crop growers in Bangladesh. It has 16 regional static laboratories and 10 Mobile Soil Testing laboratories (MSTL) namely Dhaka, Razshahi, comilla, Khulna, Mymensingh, Jamalpur, Bogra, Dinajpur, Jenida, Barisal, Noakhaly, Sylhet, Chittagong, Kustia and Faridpur.


Use of agricultural modern inputs


Modern inputs like improved varieties of seeds, fertilizers, insecticides and ground and surface water irrigation are being practiced. The use of modern technology and inputs is comparatively more intensive on soils of the Ganges river floodplain than on the tidal floodplain soils due to the problems of salinity and fresh water scarcity in the latter area and also lack of suitable salt tolerant varieties. About 70% area of Ganges floodplain could be brought under improved cropping practices. Crop screening, selection and introduction of salt tolerant varieties may increase crop yield. Traditional local varieties with poor yield have little possibility to improve the existing production system in the area. The chemical fertilizer, mainly urea is being used for moderate yield goal without knowing the site specific land and soil characteristics & existing nutrient status of the soils.


Land Use Program

Government of Bangladesh have initiated participatory bottom up planning process in the country with effect from July, 1997. It requires integrated and multi-disciplinary approach. GO/NGO's collaborative efforts will be necessary for successful implementation of land use program. Conservation of biodiversity, particularly the mangrove forest areas and promotional activities related to clientele driven technology dissemination program based on land and soil characteristics are being given top priority in the land use planning program of the region. There are sporadic success stories in co-operative farming and deserve fine-tuning and consolidation of activities for development of sustainable land use planning program.


Consideration
It is important to apply agrochemicals whenever necessary and appropriate use. Excess use of that agrochemical is now a coming disaster of our soil resource. The following measure should be taken for maintain soil fertility and sustainable agricultural production;
The Challenges-view points:
To address the challenges posed by local problems strategies for sustainable use of soil, land, water and other natural resources may be taken:

A. Policy issues

- Land zoning according to land potentials.
- Increasing trend of conversion of potential agricultural land into non-agricultural use to be minimized.
- Extensive motivation for rational use of water, fertilizers, insecticides and other inputs to restore environment and soil health (IPNS, water management, IPM).
- Marketing, price protection and preservation of agricultural commodities to be ensured.
- Illiteracy eradication and health care facilities to be enhanced.
- Rehabilitation of local drainage systems by dredging and excavation of major drainage ways is needed to mitigate the problem of drainage congestion, in combination with adaption of effective sediment/siltation control measures.
- Polder management such as maintenance of embankments, sluice gates, introduction of social forestry and development of green belt.
- Development of appropriate plans for natural disaster preparedness and post disaster rehabilitation programmes including agriculture.
- Protection of soil and water pollution from heavy metals.
- Conservation of bio-diversity and sustainable use of mangrove (Sundarbans) ecosystem.

B. Research and Technological Issues

- Effective technology transfer mechanism should be evolved to disseminate location specific agrotechnologies to the farmers.
- Use of soil test based inorganic and organic fertilizers is to be popularized.
- Development of appropriate soil management technology for irrigated rice or dryland crops on cracking heavy clays.
- Crop diversification in the western high Ganges floodplain and planned agro-fisheries in the lower areas in the east and south east.
- Groundwater abstraction should be limited to avoid abnormal drawdown to avoid inland ingression of fresh water-salt water interface and salinity upcoming.
- Development of soil tolerant germ plasm for coastal saline area is required.
- Development of appropriate technology on soil and water salinity management may be undertaken.
- Monitoring of coastal river water salinity for the demarkation of safe period of irrigation with brackish water.
- Groundwater control in the peat basin areas to avoid irreversible shrinkage of peat soils and cracking and subsidence of ground surface.
- The acid sulphate soils, active or potential, need special careful handling to avoid any further aggravation of the problems related to high acidity and aluminium toxicity.
- Effective protection of wildlife, especially of the endangered species such as The Royal Bengal Tiger, estuarine crocodiles, etc.

Beside this following measures should be considered:

-Farmer’s training for awareness of appropriate land use technique.
-Embankment in the costal area’s to protect cultivable land from salinity.
-Invent suitable saline tolerant crop variety.

CONCLUSION
Saving soil resources, for future generation, soil fertility should be ensured. For this why, timely supply and availability of fertilizers at reasonable prices at the doorsteps of the hard working farmers in the country can only ensure balanced fertilization that is very much needed for our depleted soils for optimum supply of nutrients for successful crop production and maintenance of soil health. The supply of nutrients to the soil – plant system comes from various sources, the most important sources being the organic manure and chemical fertilizers. The use efficiency of the chemical fertilizers are low and unsatisfactory because of imbalanced or under use/sometimes over use resulting in huge wastage which the country cannot afford. Therefore, the practice of balanced fertilization should receive top priority to sustain/increase crop productivity when food security is so crucial for poverty stricken people, when the country is facing challenges of increasing population and shrinking natural resources including agricultural land and also when there exists big gap between research and farmer’s yield. Conservation of bio-diversity and sustainable development of our ecosystem deserve special attention. The prosperity and further development of soil resources is a formidable task to be undertaken in an integrated and multi disciplinary approach.








REFERENCES

Bashar, M.A. 2001. Management of homestead: Plantation and agroforestry. Bangladesh
Observer. June 24 issue. Dhaka.
BBS (Bangladesh Bureau of Statistics), 2007. Statistical Yearbook of Bangladesh. Govt.
of Bangladesh. Dhaka.
BBS (Bangladesh Bureau of Statistics), 2008. Statistical Yearbook of Bangladesh. Govt.
of Bangladesh. Dhaka.
BBS (Bangladesh Bureau of Statistics), 2009. Statistical Yearbook of Bangladesh. Govt.
of Bangladesh. Dhaka.
Brammer, H. 1984. Disaster Preparedness Planning Precautionary and Rehabilitation
Measures for Agriculture, Bangladesh.
DAE-SFFP. 2002. Seminar on Soil Health Management: Department of Agricultural
Extension-Soil Fertility and Fertilizer Project Experience.

FAO-UNDP, 1988. Agroecological regions of Bangladesh. Report-2, FAO, Rome.
Huda, N and Roy, M.K. 2000. State of the forests. In Chowdhury, Q.I. (Edi.). State of
Environment Report. Forum of Environment Journalists of Bangladesh, Dhaka.

Karim, Z. and A. Iqbal. 2001. Impact of Land Degradation in Bangladesh. Bangladesh
Agricultural Research Council. Farm Gate. Dhaka. P. 60 and 160.
SRDI Staff, 1965-1986. Reconnaissance Soil Survey Reports of Various Districts. Soil
Resources Development Institute, Farm Gate. Dhaka.
Ullah, M. 2002. Biodiversity irreplaceable asset. Weekly Holiday. (8.2.2002 issue)
Center for sustainable development (CFSD). Dhaka.

PERFORMANCE OF VARIETY AND PLANTING MATERIALS ON GROWTH AND YIELD ATTRIBUTES OF SWEET POTATO

Md.Harun-or -Rashied,Md.Nurul Huda Al Mamun,A.B.M.Sahidul Islam,M.Mizanur Rahman,N.M.Jahangir
Soil Resource Development Institute, Bangladesh
ABSTRACT
The experiment was conducted at the Horticulture Farm, Bangladesh Agricultural University, Mymensingh during the period from December 2001 to May 2002 to study on the performance of variety and planting materials the growth and yield of sweet potato. There were five sweet potato varieties viz., Tripti, Kamalasunduri, Daulatpuri, BARI sweet potato-4 and BARI sweet potato-5 and three cuttings of vine viz., tip, middle and basal portion used as planting materials. There were wide variations among the varieties in most of the parameters studied. BARI sweet potato-5 produced longest vine and maximum tuberous root per plant while Tripti produced maximum number of branches per plant and Daulatpuri gave longest tuberous roots. Tip cuttings performed best in survivability, vine length, number of branches and tuberous roots per plant.
Key word: Planting materials, Variety, Growth and yield

1. INTRODUCTION
Sweet potato (Ipomoea batatas Poir) is one of the major starch rich root crops of the tropics and sub-tropics belonging to the family Convolvulaceae. It is very popular among the poor people of Bangladesh because of its low price. The tuberous roots of this crop are edible and are consumed as boiled, baked, roasted or fried forms (Onwueme, 1978). The young vine with tender leaves is also consumed as vegetable. Bangladesh produced 378 thousand metric tones of sweet potato in an area of 4089 thousand hectares of land showing an average yield of 9029 metric tones per hectare during the year 1999-2000 (BBS, 2001). The average yield is very low compared to Japan and Korea where per hectare yields are reported to be 22.7 and 21.0 t/ha respectively (FAO, 1999). The main reasons for such lower yield are mainly use of low yielding varieties and sub-optimal production practices. Only five improved varieties, namely, Tripti, Kamalasunduri, Daulatpuri, BARI sweet potato-4 and BARI sweet potato-5, have been developed by Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur (Razzaque et al. 2000). These varieties are yet to be popularized among the farmers. Sweet potatoes are propagated normally by vine cuttings. The farmers in our country generally use cut pieces of vines irrespective of the position (basal, middle or apical part of vines). It is reported some advantages of apical cutting over the use of other parts of vine in producing higher yield (Hossain and Mondal, 1994), but this is not well accepted and even not extensively practiced in sweet potato cultivation. Moreover, influence of different vine parts of different varieties were also not evaluated properly. The present work was, therefore, undertaken to find out suitable vine parts as planting material of different varieties for maximization of vegetative growth as well as yield of sweet potato.
2. MATERIALS AND METHODS
The field experiment was carried out at the Horticulture Farm of Bangladesh Agricultural University, Mymensingh during the period from December, 2001 to May, 2002 to study the performance of variety and planting materials on growth, yield and physiological attributes of sweet potato. The experimental site was located at 24.60 N latitude and 90.50 E longitudes. The soil of the experimental plot was sandy-loam in texture belonging to the Old Brahmaputra Flood Plain under the Agro-Ecological Zone 9 having non calcareous dark gray flood plain soil (FAO, 1988). The land was medium high with adequate irrigation and drainage facilities. Soil characteristics of the experimental site at a depth 0-30 cm were assessed at the “Humboldt Soil Testing Laboratory”, Department of Soil Science, Bangladesh Agricultural University, Mymensingh.. The soil characteristics were as follows: Soil pH 6.37, Organic carbon (%)0.61, Organic matter (%)1.05, Total nitrogen (%) 0.06, Available phosphorus (ppm)25.00, Available sulphur (ppm) 6.00 and Exchangeable K (meq/100 g soil) 0.07. The whole vines of these five varieties were collected from the Tuber Crops Research Centre (TCRC), Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur. Vine cuttings of sweet potato (tip, middle and basal portion) approximately 30 cm in length with at least 6-7 nodes were used. The experiment consisted two factors namely, varieties and vine cuttings which were as follows.
Factor A: It included five varieties of sweet potato such as: V1- Tripti V2-Kamalasunduri V3- Daulatpuri V4-BARI sweet potato-4 V5-BARI sweet potato-5
Factor B: Three types of vine cutting like P1-Tip cutting,P2- Middle portion vine cutting , P3- Basal portion were used as planting material . The two factor experiment was laid out in the Randomized Complete Block Design (RCBD) with three replications. The plants were spaced with 60 × 30 cm spacing (Rashid and Mannan, 1986) in unit plots of 2.4m×2.4m. The land was fertilized with well decomposed Cow dung 10 tons/ha, Urea 150 kg/ha, Triple Super Phosphate (TSP) 125 kg/ha and Murate of Potash (MP) 175 kg/ha. The entire amount of cow dung, TSP, one-fourth of urea and MP were applied to each experimental plot during final land preparation. Rest part of urea and MP were side dressed after 60 days of planting. The vine cuttings were planted in the experimental plots in the afternoon of 1 December, 2001.The intercultural operation like weeding, earthing up, irrigation, and Vine lifting and plant protection from pest were done whenever needed. Data were collected on different growth and physiological parameters of sweet potato. The plant of the outer two rows and the extreme ends of the middle rows were excluded from random selection of plant to avoid the border effects. Ten plants were randomly selected from each plot to record data on cutting survivability (%), length of vine (cm), number of branches per plant, number of tuberous roots per plant, length of tuberous roots, diameter of tuberous roots, regularity in shape and grading of tuberous roots by number.The data were analyzed to find out the significance of the difference among the treatments. The analysis was performed by F-test and the significance of the difference between pairs of treatment mean was evaluated by the Least Significant Difference (LSD) test, at 1% and 5% level of probability (Gomez and Gomez, 1984).


3. RESULTS AND DISCUSSION
3.1. Cutting survivability (%)
There was significant variation among the varieties in respect of cutting survivability recorded at 40 DAP. The highest survivability of cutting (92.97%) was found in the variety BARI sweet potato-5 followed by Daulatpuri (90.04%), Tripti (89.24%) and Kamalasunduri (84.72%) (Fig.1). It was lowest in BARI sweet potato-4 (Fig. 1). Survivability of sweet potato cutting was also affected by different types of cutting. The highest survivability of cutting (94.38%) was observed with tip cuttings followed by middle cuttings (90.43%) and the lowest survivability (77.71%) was found in basal cuttings (Table 6). The combined effect was significant .The highest percentage of cutting survivability (95.83%) was observed in the treatment combination of Tripti with tip cuttings and as well as in the treatment combination of Daulatpuri with tip cuttings (Table 7). The lowest percentage of cutting survivability (69.79%) was observed in the variety of Kamalasunduri when basal portion was used as vine cutting and also in variety BARI sweet potato-4 when basal cutting was used. The survivability of cuttings was higher in tip and middle cuttings in comparison with basal cuttings. High mortality rate incase of basal cuttings was perhaps due to over maturity of tissue, absence of leaves and number of leaf buds from where endogenous hormone was supposed to form and help in the initiation of roots. Shanmugavelu et al. (1972) reported poor establishment of cuttings when leaves were removed before planting.
3.2. Length of vine (cm)
There was a significant difference in vine length among the varieties recorded at 45, 60, 75, 90, 105, 120 DAP and at harvest. At harvest, the variety BARI sweet potato-5 produced longest (207.66 cm) vine followed by Kamalasunduri (182.21 cm), Tripti (177.52 cm) and BARI sweet potato-4 (160.90 cm). Where as, the shortest (96.86 cm) vine length was recorded in Daulatpuri (Fig. 2).The length of the vine per plant was significantly influenced by vine parts .At harvest, tip cuttings produced the highest length of vine (173.73 cm) (Table 6). The shortest length of vine was produced by basal cuttings (158.30 cm)(Table 6).The length of the longest vine was found significantly different due to the combined effect of varieties and vine parts at different days after planting .At harvest, the length of the longest vine (216.00 cm) was found in the treatment combination of variety BARI sweet potato-5 with middle portion vine cuttings and the shortest length of the vine (92.43 cm) was found in the treatment combination of variety Daulatpuri with basal cuttings (Table 7). There was also significant interaction between different varieties and vine parts at harvest in this respect. Tip cuttings produced maximum length of vine might be due to early survivability and high vigor of tip cuttings for subsequent growth of vine.
3.3. Number of branches per plant
At harvest, number of branches per plant ranged from 14.93 to 18.81 (Fig. 3) among different varieties. The maximum number of branches per plant was produced by the variety Tripti and it was minimum Kamalasunduri (14.93). Rests of the three varieties were statistically similar in this respect. Differences in branching might be due to genotypic variation. The number of branches per plant differed significantly by different types of cutting (Fig.3) .At harvest, the highest number of branches (19.71) per plant was found in tip cuttings and the lowest number of branches (15.77) was found in basal cuttings (Table 6). The interaction effect between variety and vine parts was found to be significant in respect of number of branches per plant at harvest. The highest (23.92) number of branches was obtained from the treatment combination of Tripti with tip cutting and lowest (14.27) from BARI sweet potato-5 with basal cutting (Table 7).
The plants from tip cuttings gave more branches because of the fact that tip cuttings established quickly in the soil by initiating more roots and thereby encouraged subsequent production of more branches. This finding agrees with the results of Chowdhury et al. (1986).
3.4. Number of tuberous roots per plant
There was significant variation among the varieties in respect of number of tuberous roots per plant (Table 1). The highest number of tuberous roots per plant (4.54) was found in the variety BARI sweet potato-5 followed by the variety of Kamalasunduri (3.92), BARI sweet potato-4 (3.89) and Tripti (3.73).The lowest number of tuberous roots per plant (3.42) was obtained from variety Daulatpuri. Siddique (1985) found that the number of tuberous root per plant varied from 1.78 to 6.03. The number of tuberous roots per plant was significantly influenced by vine parts (Table 2). The highest number of tuberous roots per plant (4.52) was obtained from tip cuttings which was statistically different from others. The minimum number of tuberous roots (3.41) was produced by the basal cuttings which differed statistically from middle cuttings (3.78). Bhuiyan and Chowdhury (1984) found that tip cuttings produced greater number of tuberous roots than other two types of cutting. The interaction between variety and vine part was significant and their combined effect was also significant in respect of number of tuberous root (Table 3). The highest number of tuberous roots per plant (5.27) was found in the treatment combination of BARI sweet potato-5 with tip cuttings and lowest (3.03) from Daulatpuri with basal cuttings.
3.5. Length of tuberous roots
A wide variation was observed in length of tuberous root among the varieties (Table 1). The variety Daulatpuri produced maximum (13.93 cm) length of tuberous roots and Tripti produced minimum (10.28 cm) length of tuberous roots which was statistically similar with the variety BARI sweet potato-5 (10.54 cm). The variety Kamalasunduri produced length of tuberous root 11.24 cm which was statistically similar with BARI sweet potato-4 (11.66 cm). Hafizuddin and Haque (1979) reported that length of tuberous roots varied from variety to variety. The effect of vine parts on length of tuberous root was significant (Table 2). The maximum length of tuberous roots (12.48 cm) was found from tip cuttings and lowest (10.60 cm) from basal cuttings. The combined effect of different variety and vine parts in respect of length of tuberous root showed significant variation (Table 3). The maximum length of tuberous roots (15.60 cm) was found in the treatment combination of variety Daulatpuri with tip cuttings.


3.6. Diameter of tuberous roots
The diameter of tuberous roots varied markedly among the varieties (Table 1). The highest diameter of tuberous roots (4.92 cm) was found in variety Kamalasunduri that was statistically similar to the diameter of tuberous roots of Tripti (4.84 cm) and BARI sweet potato-4 (4.68 cm). This might be due to the varietal characteristics. The diameter of tuberous root significantly influenced by vine parts (Table 2). The maximum diameter of tuberous roots (4.94 cm) was recorded from tip cuttings followed by middle cuttings (4.49 cm) and the basal cuttings (3.98 cm). The combined effect of different variety and vine parts was found significant on the diameter of tuberous roots (Table 3). The largest diameter of tuberous root (5.70 cm) was obtained from variety Tripti with tip cuttings and the minimum (3.45 cm) was obtained from Daulatpuri with basal cuttings which was statistically similar to the same variety with middle cuttings (3.53 cm).
3.7. Regularity in shape of tuberous root
Regularity in shape exhibited significant variation on different varieties (Table 1). The score of regularity in shape of tuberous root as influenced by variety ranged from 2.93 to 6.57. The highest score (6.57) was obtained from BARI sweet potato-5 followed by BARI sweet potato-4 (5.57), Kamalasunduri (4.40) and Daulatpuri (3.40). The lowest score (2.93) was found in the variety Tripti. Vine cuttings also had significant effect on regularity in shape of tuberous root (Table 2). Maximum regular tuber was found with tip cuttings scored highest (5.26), while the lowest score (3.88) was found in basal cuttings. There was significant interaction between type of cutting and varieties on the production of regular shape of tuberous roots. The highest score for regular shape of tuberous root (7.5) was obtained from BARI sweet potato-5 with middle cuttings which was statistically similar with tip cuttings (7.00) of same variety (Table 3).
3.8. Grading of tuberous roots by number
There was a significant difference in distribution of tuberous root sizes among the varieties (Table 4). The highest percentage (25.55) of large (>200 g) tuberous roots was found in the variety Tripti, which was statistically similar with Kamalasunduri (25.06%) and BARI sweet potato-5 (23.90%). The variety Kamlasundari produced the highest percentage (45.04%) of medium tuberous root (100 to 200 g) and the lowest (38.92%) was found in the variety Daulatpuri. In case of small (<100 g) tuberous root, the highest percentage (41.15%) was found in the variety Daulatpuri followed by BARI sweet potato-4 (37.27%), BARI sweet potato-5 (37.20%) and Tripti (33.18%). Vine cuttings also showed significant variation on grading of tubers (Table 5). The highest percentage (26.99%) of large tuberous roots was found in tip cuttings followed by middle cuttings (23.36%) and basal cuttings (20.05%). In case of medium (100-200 g) tuberous root, the highest percentage (41.16%) was found from basal cuttings and lowest (40.71%) from tip cuttings. The highest percentage (39.08%) of small tuberous roots was obtained from basal cuttings which differed statistically from tip and middle cuttings.
4. Conclusion: There were wide variations among the varieties in most of the characters studied. None of the varieties was found best in all parameters. Tip cuttings performed best in all cases of the study.
References:
BARI. 1998. Sweet Potato (Leaflet in Bengali). Tuber Crops Research Centre, Bangladesh Agricultural Research Institute, Joydebpur, Gazipur.
BBS. 2001. Monthly Statistical Bulletin of Bangladesh, May 2001. Bangladesh Bureau of Statistics. Statistics Division, Ministry of Planning, Govt. of the Peoples Republic of Bangladesh, Dhaka. p. 55.
Bhuiyan, M.A.J. and A.R. Chowdhury. 1984. Effect of methods of planting and types of cutting on the growth and yield of sweet potato. Bangladesh J. Agril. Res., 9(1): 27-32.
Chowdhury, S.H., S.U. Ahmed and A.F.M. Sharfuddin. 1986. Effect of number of nodes in different types of vine
cutting on the growth and yield of swees potato. Bangladesh Hort. 14(1): 29-33.
FAO. 1988. FAO Production Year Book. Basic Data Unit. Statistics Division, Food and Agricultural Organization of the United Nations, Rome, Italy, 48:90.
FAO. 1999. FAO Production Year Book. Basic Data Unit. Statistics Division, Food and Agricultural Organization of the United Nations, Rome, Italy, 53:95.
Gomez, K.A. and A.A. Gomez. 1984. Statistical Procedure for Agricultural Research (2nd ed.). John Wiley & sons, Singapore. pp. 18-192.
Hafizuddin, M. and M.A. Haque. 1979. Effect of nitrogen and potash at different levels on the yield of two local varieties of sweet potato. Bangladesh Hort. 7(1&2) : 18-23.
Hossain, M.M. and M.A.A. Mondal. 1994. Effects of vine parts on the growth and yield of three sweet potato varieties. Bangladesh J. Sci. and Ind. Res. 29(3): 181-184.
Onwueme, I.C. 1978. The Tropical Tuber Crops: Yams, Cassava, Sweet potato and Cocoyams. English Language Book Society and John Wiley & Sons, Chichester. p. 179.
Rashid, M.M. and M.A. Mannan. 1986. Mitha Alur Chash (in Bengali). Root Crop Project, Bangladesh Agril. Res. Inst., Joydebpur, Gazipur. pp. 5-10.
Razzaque, M. A., M.A. Sattar, M.S. Amin, M.A. Quiyum and M.S. Alam. 2000. Krishi Projukti Hatboi (Handbook on Agro-technology). (2nd ed.). Bangladesh Agricultural Research Institute, Gazipur 1701, Bangladesh. pp. 211-222.
Shanmugavelu, K.G., S. Thamburaj and A. Shanmugan. 1972. Studies on the effect of time of planting and type of planting materials on the yield of sweet potato. South Indian Hort., 20(1/14): 55-58.
Siddique, M.A.R. 1985. Studies on the morphology, growth and yield of some sweet potato genotypes. M.Sc.(Ag.) thesis, Dept. of Hort., Bangladesh Agril. Univ., Mymensingh.
Table 1. Main effect of variety on the growth and yield contributing characters of sweet potato
Variety Number of tuberous roots/plant Length of tuberous roots (cm) Diameter of tuberous roots (cm) Regularity in shape of tuberous roots (score)
V1 3.73 10.28 4.84 2.93
V2 3.92 11.24 4.92 4.40
V3 3.42 13.93 3.81 3.40
V4 3.89 11.66 4.68 5.57
V5 4.54 10.54 4.09 6.57
LSD (0.05) 0.354 0.605 0.423 0.372
LSD (0.01) 0.477 0.817 0.571 0.501












V1 : Tripti V2 : Kamalasunduri V3 : Daulatpuri V4 : BARI Sweet Potato – 4 V5 : BARI Sweet Potato – 5
Table 2. Main effect of vine parts on the growth and yield contributing characters of sweet potato

Vine parts Number of tuberous roots/plant Length of tuberous roots (cm) Diameter of tuberous roots (cm) Regularity in shape of tuberous roots (score)
P1 4.52 12.48 4.94 5.26
P2 3.78 11.51 4.49 4.58
P3 3.41 10.60 3.98 3.88
LSD (0.01) 0.369 0.369 0.442 0.388
P1 : Tip cutting P2 : Middle portion vine cutting P3 : Basal portion vine cutting
Table 3. Combined effect of variety and vine parts on the growth and yield contributing characters of sweet potato
Treatment combination Number of tuberous roots/plant Length of tuberous roots (cm) Diameter of tuberous roots (cm) Regularity in shape of tuberous roots (score)
V1P1 4.67 11.24 5.70 3.60
V1P2 3.53 9.42 4.80 3.00
V1P3 3.20 10.17 4.03 2.20
V2P1 4.30 11.79 5.10 5.50
V2P2 3.70 11.92 5.53 4.20
V2P3 3.43 9.99 4.13 3.50
V3P1 3.83 15.60 4.43 4.00
V3P2 3.40 12.59 3.53 3.20
V3P3 3.03 13.60 3.45 3.00
V4P1 4.73 12.29 5.13 6.20
V4P2 3.63 13.21 4.17 5.00
V4P3 3.30 9.47 4.73 5.50
V5P1 5.27 11.48 4.33 7.00
V5P2 4.63 10.39 4.40 7.50
V5P3 3.73 9.75 3.53 5.20
LSD (0.01) 0.826 1.414 0.989 0.868
CV (%) 9.40 5.44 9.82 8.41

V1 : Tripti V2 : Kamalasunduri V3 : Daulatpuri V4 : BARI Sweet Potato – 4 V5 : BARI Sweet Potato - 5
P1 : Tip cutting P2 : Middle portion vine cutting P3 : Basal portion vine cutting












Table 4. Main effect of variety on grading of tuberous root by number and by weight
Variety Grading of tuberous roots (%)
> 200 g 100-200g <100g
V1 25.55 41.26 33.18
V2 25.06 45.04 30.24
V3 20.18 38.92 41.15
V4 22.64 39.87 37.27
V5 23.90 39.81 37.20
LSD (0.01) 2.213 2.798 2.534
V1 : TriptiV2 : KamalasunduriV3 : DaulatpuriV4 : BARI Sweet Potato – 4 V5 : BARI Sweet Potato – 5
Table 5. Main effect of vine cuttings grading of tuberous roots by number.
Vine parts Grading of tuberous roots (%)
>200 g 100-200 g <100 g
P1 26.99 40.71 32.34
P2 23.36 41.08 36.01
P3 20.05 41.16 39.08
LSD (0.05) 1.270 -- 1.455
LSD (0.01) 1.714 -- 1.963
P1 : Tip cutting P2 : Middle portion vine cutting P3 : Basal portion vine cutting

Table 6. Main effect of vine parts on the cutting survivability (%), length of vine (cm) and
number of branches of sweet potato

Vine parts Cutting survivability at 40 DAP(%) Length of vine At harvest (cm) Number of branches per plant At harvest
P1 94.38 173.73 19.71
P2 90.43 163.01 17.41
P3 77.71 158.30 15.77
LSD (0.05) 3.408 2.623 0.867
LSD (0.01) 4.597 3.539 1.170
P1 : Tip cutting P2 : Middle portion vine cutting P3 : Basal portion vine cutting


Table 7. Combined effect of variety and vine cuttings on the cutting survivability (%), length of vine (cm)
and number of branches of sweet potato
Treatment combination Cutting survivability at 40 DAP (%) Length of vine (cm)
at harvest Number of branches
at harvest
V1P1 95.83 189.80 23.92
V1P2 92.71 172.40 19.80
V1P3 79.17 170.37 15.95
V2P1 94.79 207.70 14.67
V2P2 89.58 171.27 15.00
V2P3 69.79 167.67 15.84
V3P1 95.83 95.03 21.67
V3P2 93.83 103.10 17.73
V3P3 80.46 92.43 14.83
V4P1 90.63 171.47 18.62
V4P2 81.25 152.30 16.37
V4P3 69.79 158.93 16.50
V5P1 94.79 204.63 18.17
V5P2 94.79 216.00 19.16
V5P3 89.33 202.33 14.27
LSD (0.05) 7.62 6.217 1.939
LSD (0.01) 10.28 8.387 2.616
CV (%) 5.21 2.13 6.83

















V1 : TriptiV2 : KamalasunduriV3 : DaulatpuriV4 : BARI Sweet Potato – 4 V5 : BARI Sweet Potato - 5
P1 : Tip cutting P2 : Middle portion vine cutting P3 : Basal portion vine cutting

Climate change begins to affect Bangladesh

CLIMATE of Bangladesh is changing day by day.It is affecting Bangladesh in many ways. For instance, rising sea levels are making some coastal agricultural land more saline, affecting both the quality and quantity of the produce. Bangladesh urgently needs support to develop climate-resilient agriculture for its people to survive and prosper in the long term, according to some experts. In its southern districts where the land is only centimetres above the brackish estuarine water, large swathes of crop land are becoming arid. Crop yields are shrinking because of deeper saline intrusion due to a rising Bay of Bengal. Agronomists and agricultural experts worry that creeping salinity would engulf more and more land in the low-lying country. "The impact of climate change on agriculture is undeniable and will most certainly worsen if governments and donors fail to take suitable steps right now," Ghulam Mohammad Panaullah, former research director of the Bangladesh Rice Research Institute (BRRI), warned. In the coastal areas, cocoa-nut and betel-nut trees do not yield half of what they did two decades ago, while banana groves are dying in hundreds, Panaullah told IRIN. Vegetables, from the coastal belt sold in urban Dhaka, Khulna and Rajshahi are deemed tasteless and fetch low prices compared to the produce from salt-free regions. In a country where almost 80 per cent of the population lives in rural areas, this is bad news. According to the World Bank, Bangladesh's agriculture sector accounts for about 22 per cent of gross domestic product (GDP), and another 33 per cent of GDP comes from the rural non-farm sectors, though very much linked to agriculture. Around 54 per cent of the rural population is employed in agriculture. ActionAid in a report on the UN climate change summit in Poznan, Poland, said Bangladesh needs the support to develop its climate-resilient agriculture.Citing an Intergovernmental Panel on Climate Change (IPCC) report, which said that South Asia might experience a 30 per cent drop in agricultural production by 2050, Action Aid said the slide was already evident. Food price volatility, which could be compounded by increasing climate change variability, is likely to be a serious problem in the foreseeable future, according to Action Aid. The report said support for sustainable climate-resilient agriculture was key to enabling farmers to adapt and increase food security. To address the problem, farmers have taken to the new technique of raising their vegetable beds. To preserve the soil's moisture they cover the seedbeds with straw and leaves. The technique prevents excessive evaporation and erosion. They are also increasing the use of organic manure to raise crops.Others are readjusting their cropping patterns altogether, the report said. "Bangladesh is one of the worst affected among countries that are facing the early impacts of climate change," said A.K.M. Rezaul Kabir, secretary in the Ministry of Environment and Forestry. In 2005 the government prepared a National Action Plan on Adaptation (NAPA) identifying 15 projects that need to be undertaken. But, "unfortunately three years have already passed and we have only just started implementing the first project," the official said. Bangladesh tops the Global Climate Risk Index 2009, followed by North Korea and Nicaragua. Launched at the UN climate change conference in Poznan on December 04, 2008, the index, drawn up by the international NGO Germanwatch, lists 170 countries. Natural calamities in Bangladesh claimed 4,729 lives last year, and the average loss of property in Bangladesh due to natural disasters stands at over US$4.0 billion per year, the NGO said. These changes in climate are already having major impacts on the economy and on the lives and livelihoods of millions of poor people, said a World Bank report. Rainfall increases, during the summer monsoon, could increase flooding in more vulnerable areas in Bangladesh, say the forecasts. In the longer term, global warming could melt many glaciers to swell the rivers in South Asia, the report said. If that happens, green Bangladesh would turn into a grey desert and most people would die of starvation.

Therefore,we should take nesessary action to protect our Bangladesh from affecting climate change.