Soil test crop response studies on integrated nutrient management in direct seeded rice – wheat cropping sequence
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Date
2019-12
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Field experiments were conducted as per technical programme of AICRP on STCR in B2 block of Norman E. Borlaug Crop Research Centre, G.B. Pant University of Agriculture and Technology, Pantnagar, (290 N latitude, 79029’ E longitude and 243.84 meters above MSL), from rabi 2016-17 to 2018-19 to work out soil test crop response based fertilizer nutrient requirement for targeted yield of direct seeded rice and wheat in sequence. Prior to test crop experiment whole experimental area was divided into three equal strips and soil fertility gradient created artificially by applying graded doses of nutrients in these strips and wheat was grown as an exhaust crop during rabi 2016-17. Test crop of direct seeded rice and wheat in sequence were grown during 2017-18 after dividing each strip in 24 plots (21 treatments and 3 controls). Crop response to selected combinations of four levels of nitrogen (0, 60, 120 and 180 kg N ha-1), four levels of phosphorus (0, 30, 60 and 90 kg P2O5 ha-1), four levels of potassium (0, 20, 40 and 60 kg K2O ha-1) and three levels of FYM (0, 5 and 10 t ha-1) in different fertility strips was studied. After test crop experiment, verification experiment was also conducted during 2018-19 to study the effect of nutrient management practices on yield, nutrient content, uptake, fertilizer economics, nutrient use efficiency and soil fertility in direct seeded rice-wheat cropping sequence. The value of soil organic carbon, alkaline KMnO4-N, Olsen’s-P and NH4OAc-K ranged between 0.314 to 0.971 percent, 125.44 to 200.70 kg ha-1, 14.37 to 21.74 kg ha-1 and 122.08 to 173.60 kg ha-1, respectively before the test crop experiment on direct seeded rice while, before test crop wheat, these values ranged between 0.457 to 0.886 percent, 112.90 to 238.34 kg ha-1, 13.63 to 24.32 kg ha-1 and 133.28 to 212.80 kg ha-1, respectively. Grain yield of direct seeded rice and wheat varied from 22.73 to 67.05 and 6.82 to 64.77 q ha-1, respectively. Average uptake of N, P and K by direct seeded rice was 87.64, 19.25 and 131.55 kg ha-1 while, in wheat it was 84.76, 17.24 and 84.15 kg ha-1, respectively. Nutrient requirement to produce one quintal grain yield of direct seeded rice was 2.01 kg N, 0.440 kg P and 3.06 kg K while for wheat 2.16 kg N, 0.447 kg P and 2.29 kg K. Percent contribution of N, P and K from soil was 22.05, 37.34 and 41.48 in direct seeded rice and 12.02, 14.82 and 11.00 in wheat, respectively. Whereas, from FYM it was 23.25, 28.34 and 16.80 percent in direct seeded rice, 12.83, 19.48 and 35.07 percent in wheat for N, P and K, respectively. Percent contribution of N, P and K from fertilizer was 38.08, 49.93, 252.98 in direct seeded rice and 53.54, 60.24 and 231.84 in wheat, respectively. Percent contribution from combined use of fertilizer and FYM was 44.83, 60.57 and 278.70 in direct seeded rice and 60.26, 70.66 and 275.41 in wheat for N, P and K, respectively. Fertilizer nutrient prescription equations for targeted yield of direct seeded rice and wheat were developed with and without FYM and it was found that for a particular yield target fertilizer nutrient requirement decreased with increasing soil test values, however for a particular soil test value nutrient requirement increased with increasing yield targets. Application of FYM reduced the fertilizer nutrient requirement for both the crops. Coefficient of determination was found highly significant (0.341** in direct seeded rice and 0.880** in wheat) by taking grain yield as dependent variable, while soil test values, added fertilizer nutrients and their interactions as independent variables. Post harvest prediction equations were also developed for predicting soil test value for available N, P and K after direct seeded rice, after wheat and after whole sequence. Less deviation was found between observed and predicted soil test value indicated the validity of post harvest soil test equations. Results of verification experiment clearly indicated the superiority of STCR target yield approach over other nutrient management practices to improve yield, economics and soil fertility in direct seeded rice-wheat cropping sequence. Therefore, findings of present study may be used for fertilizer nutrient prescription in similar type of soils and climate after its verification at farmer’s fields.
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