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.

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