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 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).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 maximum pH, N, P and S status of soil were recorded in T3 treatment. But the highest value of organic matter and exchangeable K in soil were observed in T1.
Key words: Phosphate rock, Nutrient Uptake, Wheat, Old Himalayan Piedmont Plain
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, 1997).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.
MATERIALS AND METHODS
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. 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).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. 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.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).
RESULTS AND DISCUSSION
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 (1.25%) was obtained in T3 treatment while control treatment showed the minimum N content (1.07%).But the treatments T3 and T4 were statistically identical. Nitrogen uptake by wheat (cv Kanchan) also varied significantly. The highest N uptake (31.13 kg ha-1) was obtained in T3 treatment followed by T4 treatment (29.64 kg ha-1). The lowest value (19.50 kg ha-1) was noted in control treatment.
Phosphorus content and uptake by wheat plant
The P content in wheat plant at PI stage was significantly influenced by different treatments (Table 1).The P content ranged from 0.091 to 0.279%.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 (6.95 kg ha-1) which was statistically similar to T4 treatment (6.32 kg ha-1). The control treatment showed the minimum P uptake (1.66 kg ha-1).
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 1.05 to 1.29% (Table 1).The highest value was obtained in T3 treatment which was statistically similar to T4 treatment and control treatment showed the lowest K content. K uptake by wheat plant responded significantly due to different treatments ranged from19.07 to 32.12 kg ha-1.The highest K uptake (32.12 kg ha-1) was indicated in T3 treatment and lowest value (19.07 kg ha-1) was found in control.
S content and uptake by wheat plant
Result presented in Table 1.showed that S content increased significantly by different treatments. S content in wheat plant varied from 0.140 to 0.165%. 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 (4.10 kg ha-1) was obtained in T3 treatment and the lowest value (2.54 kg ha-1) was found in control and the S uptake ranged from 2.54 to 4.10 kg ha-1(Table 1).
Table 1. Effects of different treatments on nutrient content and uptake by wheat (cv.Kanchan) at panicle initiation stage
Treatments
|
Content (%)
|
Uptake (kg ha-1)
| |||||||
N
|
P
|
K
|
S
|
N
|
P
|
K
|
S
| ||
T1
|
1.07
|
0.091c
|
1.05b
|
0.140b
|
19.50d
|
1.66c
|
19.07d
|
2.54d
| |
T2
|
1.19
|
0.215ab
|
1.12b
|
0.141a
|
24.39c
|
4.40b
|
23.04c
|
2.89c
| |
T3
|
1.25
|
0.279a
|
1.29a
|
0.165a
|
31.13a
|
6.95a
|
32.12a
|
4.10a
| |
T4 *
|
1.20
|
0.256b
|
1.24a
|
0.156b
|
29.64b
|
6.32a
|
30.62b
|
3.85b
| |
SE (±)
|
NS
|
0.0024
|
0.0301
|
0.0352
|
0.5287
|
0.03459
|
0.3644
|
0.1640
| |
CV (%)
|
9.76
|
2.33
|
5.13
|
4.69
|
4.06
|
14.32
|
2.78
|
5.98
| |
*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.
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 1.87 to 2.15% (Table 2). 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 0.422 to 0.672% and the maximum concentration of N content was obtained in the T3.TSP had shown better effect over direct and residual effect of PR.
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 38.52 to 75.68 kg ha-1.The maximum N uptake was noted in T3 treatment and the lowest N uptake was recorded in control (Table 2).The second highest N uptake was found in T4 treatment. The treatment T4 was significantly superior that T2. Similarly, in case of straw, N uptake ranged from 12.70 to 35.21 kg ha-1. The maximum 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.
Table 2. Effects of different treatments on N concentration and N uptake by wheat (cv.Kanchan) at harvest.
Treatments
|
N content (%)
|
N uptake (kg ha-1)
|
Total N uptake (kg ha-1)
| |||
Grain
|
Straw
|
Grain
|
Straw
| |||
T1
|
1.87c
|
0.422d
|
38.52d
|
12.70d
|
51.22d
| |
T2
|
1.99b
|
0.493c
|
49.75c
|
20.31c
|
70.06c
| |
T3
|
2.15a
|
0.672a
|
75.68a
|
35.21a
|
110.89a
| |
T4 *
|
2.03b
|
0.552b
|
63.33b
|
27.93b
|
91.26b
| |
SE (±)
|
0.0346
|
0.010
|
0.369
|
0.3840
|
1.477
| |
CV (%)
|
3.44
|
3.74
|
4.30
|
3.20
|
10.18
| |
*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.
Total N uptake ranged from 51.22 to 110.89 kg ha-1. The maximum total N uptake was found in T3 treatment and the lowest 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.
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 0.223 to 0.319 % (Table 3).The maximum P content (0.319%) was observed in T3 treatment followed T2(0.291%) and T4 (0.299%).The minimum P content was observed in control treatment. The highest P content in straw was attained in T3 (1.61%) followed by T2 (0.110%) and T4 (0.146%) and the minimum P content (0.044%) 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.
Table 3.Effects of different treatments on P concentration and P uptake by wheat (cv.Kanchan) at harvest.
Treatments
|
P content (%)
|
P uptake (kg ha-1)
|
Total P uptake (kg ha-1)
| |||
Grain
|
Straw
|
Grain
|
Straw
| |||
T1
|
0.223b
|
0.044b
|
4.79d
|
1.32d
|
6.11d
| |
T2
|
0.291a
|
0.110a
|
7.27c
|
4.53c
|
11.80c
| |
T3
|
0.319a
|
0.161a
|
11.23a
|
8.43a
|
19.66a
| |
T4 *
|
0.299a
|
0.146a
|
9.32b
|
7.38b
|
16.70b
| |
SE (±)
|
0.0035
|
0.0033
|
0.2771
|
0.2785
|
0.4332
| |
CV (%)
|
2.45
|
5.70
|
6.80
|
12.34
|
6.88
| |
*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.
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 (11.23 kg ha-1) treatment from TSP source and minimum P uptake (4.79 kg ha-1) was in control. Similar trend was also noticed in case of total P uptake. In case of straw, the highest amount of P uptake (8.43 kg ha-1) was noted in T3 treatment and lowest amount of P uptake (1.32 kg ha-1) was found in control. Similar trend was also noticed in case of total P uptake varied from 6.11 to 19.66 kg ha-1(Table 3). The second highest total P uptake (16.70 kg ha-1) was found in T4 treatment. 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).
K content in grain and straw
The K content in grain ranged from 0.401 to 0.463% (Table 4). The maximum K content was recorded in T3 treatment and the control treatment showed the minimum K content. The second highest K content was found in T4 treatment which was statistically similar to T3. 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 (1.49%) in straw was found in T3 treatment and the minimum K content (1.27%) was obtained in control treatment.
K uptake in grain and straw
K uptake by grain ranged from 8.26 to 16.30 kg ha-1(Table 4.).The treatments increased the K uptake significantly over control. The highest K uptake was recorded in T3 treatment and the control treatment showed the minimum K uptake. The second highest K uptake by grain was found in T4 treatment. In case of straw, K uptake varied significantly due to different treatment. The uptake in straw ranged from 38.23 to 78.07 kg ha-1. The highest K uptake was observed in T3 treatment and lowest K uptake was found in control. The second highest K uptake was obtained in T4 treatment. Results in Table 4. showed that total K uptake varied significantly (from 46.49to 94.37 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. Total K uptake of T4 treatment was superior to T2 treatment. 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).
Table 4. Effects of different treatments on K concentration and K uptake by wheat (cv.Kanchan) at harvest.
Treatments
|
K content (%)
|
K uptake (kg ha-1)
|
Total K uptake (kg ha-1)
| |||
Grain
|
Straw
|
Grain
|
Straw
| |||
T1
|
0.401b
|
1.27c
|
8.26d
|
38.23d
|
46.49d
| |
T2
|
0.412b
|
1.43ab
|
10.30c
|
58.50c
|
68.80c
| |
T3
|
0.463a
|
1.49a
|
16.30a
|
78.07a
|
94.37a
| |
T4 *
|
0.455a
|
1.38b
|
14.20b
|
69.82b
|
84.02b
| |
SE (±)
|
0.0036
|
0.0289
|
0.3516
|
0.5153
|
1.1630
| |
CV (%)
|
1.68
|
4.15
|
5.73
|
4.68
|
3.19
| |
*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.
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 0.273 to 0.331% (Table 5). The highest S content was observed in T3 treatment the lowest S content was found in control treatment.T4 treatment was superior to T2 treatment.In case straw, S content varied from 0.101 to 0.126 % (Table 5). The maximum S content was recorded in T3 treatment which was statistically similar to T2 and T4 treatments. The control treatment obtained minimum S control (Table 5).
Table 5. Effects of different treatments on S concentration and S uptake by wheat (cv.Kanchan) at harvest.
Treatments
|
S content (%)
|
S uptake (kg ha-1)
|
Total S uptake (kg ha-1)
| |||
Grain
|
Straw
|
Grain
|
Straw
| |||
T1
|
0.273b
|
0.101b
|
5.62d
|
3.04c
|
8.66d
| |
T2
|
0.285ab
|
0.116ab
|
7.12c
|
4.78b
|
11.90c
| |
T3
|
0.331a
|
0.126a
|
11.65a
|
6.60a
|
18.25a
| |
T4 *
|
0.325ab
|
0.120a
|
10.14b
|
6.07a
|
16.21b
| |
SE (±)
|
0.051
|
0.0051
|
0.3946
|
0.3196
|
0.5538
| |
CV (%)
|
3.38
|
8.79
|
9.14
|
12.51
|
8.06
| |
*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.
S uptake in grain and straw
Results shown in Table 5. indicated that S uptake by grain was also significantly influenced by different treatments. The range of S uptake observed in grain was 5.62 to 11.65 kg ha-1.All treatments were statistically significant over in T3 treatment and the minimum S uptake was noted in control. In case of straw, the maximum S uptake was recorded in T3 treatment which was statistically similar to T4 treatment. The control treatment obtained minimum S uptake and the range was 3.04 to 6.60 kg ha-1. Application of PR and TSP had significant effect of total S uptake (Table 5).The highest total S uptake (18.25 kg ha-1) was found in T3 treatment and the lowest total S uptake was observed in control treatment (8.66 kg ha-1). Total uptake of T4 treatment was better that of T2 treatments. Works of different investigators (Joshi and Seth, 1975; Ahmed, 1993) also revealed that the P fertilization increased S content and uptake of wheat grain.
Characteristics of post harvest soils
Table 6 revealed the characteristics of the post harvest soil as influenced due to different treatments. 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 5.42 to 5.61,whereas the initial soil pH value ranged from 5.12 to 5.92. The highest pH value (5.61) was recorded in T3 treatment followed by T2 (5.60) and T4 (5.52). The lowest pH value (5.42) was recorded in T1 treatment. The organic matter content of the post harvest soil range varied from 1.40 to 1.45% whereas the initial soil organic matter range varied from 1.41 to 1.51 %( Table 6). The highest organic matter content was obtained in control (1.45%) and the minimum organic matter content (1.40%) was obtained in T3 treatment. The variation of soil organic matter content was insignificant. The total N content of the post harvest soil varied from 0.130 to 0.145% (Table 6), where the initial soil total N varied from 0.126 to 0.132%. The highest total N was observed in control treatment and the lowest total N was found in 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 11.32 to 16.49 ppm, where the initial soil available P content range varied from 11.26 to 16.48 ppm. The highest available P content was recorded in the treatment T3 and the lowest available P content was found in control treatment. The exchangeable K content of post harvest soils ranged from 0.120 to 0.140 cmol kg-1 whereas the initial soil exchangeable K content range varied from 0.118 to 0.141 cmol kg-1.The highest exchangeable K content was observed in control and the lowest exchangeable K content was found in T2 treatment. The treatments T3 and T4 were statistically similar. Available S content of post harvest soils influenced significantly due to different treatments (Table 6). The maximum S content (14.60 ppm) was observed in T3 treatment followed by T2 and T4.The minimum available S content (11.29 ppm) was observed in control. The available S content of initial soil ranged from 11.29 to 14.60 ppm.
Table 6.Soil pH, Organic matter, N,P,K and S contents of the post-harvest soils with initial soils as influenced by PR at Wheat Research Sub-centre, Dinajpur
Treatments
|
pH
|
Organic matter (%)
|
Total nitrogen (%)
|
Available phosphorus (ppm)
|
Exchangeable potassium (cmolkg-1 100g soil)
|
Available sulphur
(ppm)
| |
T1
|
5.42
(5.25)
|
1.45
(1.51)
|
0.145
(0.129)
|
11.32d
(11.26)
|
0.140a
(0.141)
|
11.29d
(11.18)
| |
T2
|
5.60
(5.22)
|
1.43
(1.42)
|
0.135
(0.126)
|
15.25c
(13.32)
|
0.120b
(0.118)
|
13.10b
(12.68)
| |
T3
|
5.61
(5.12)
|
1.40
(1.41)
|
0.130
(0.129)
|
16.49a
(16.48)
|
0.132ab
(0.124)
|
14.60a
(14.62)
| |
T4 *
|
5.52
(5.92)
|
1.41
(1.44)
|
0.135
(0.132)
|
16.20b
(13.31)
|
0.127ab
(0.124)
|
11.89c
(11.70)
| |
SE (±)
|
NS
|
NS
|
NS
|
0.773
(0.281)
|
0.0026
(0.0087)
|
0.0662
(0.367)
| |
CV (%)
|
1.33
(2.50)
|
2.04
(1.75)
|
3.71
(1.00)
|
1.04
(4.14)
|
4.07
(13.68)
|
1.04
(5.85)
|
*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. Values in parenthesis indicate initial condition of soil.
CONCLUSION
From the results it is evident 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 (210 kg P ha-1 was applied in previous crop) showed comparatively better performance than T2 (20 kg P ha-1 applied directly) 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.
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