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Assessing the indigenous nutrient supplying capacity of soils to Soybean in Vertisols of Northern Karnataka

A study was undertaken in the farmer fields growing soybean in Northern Karnataka with the following objectives 1. To assess the fertility status of soils in soybean growing areas of Northern Karnataka and to study the response of soybean to major nutrients and response variability across spatial and temporal scale. 2. To study the nutrient uptake pattern, nutrient use efficiency and residual soil fertility through nutrient omission technique. 3. To create awareness among farmers for optimized nutrient use and best nutrient management practices for soybean

IPNI-2014-IND-531

Overview Related Interpretive Summary
22 May 2017

2016 Annual Interpretive Summary


The study was initiated to determine the response of soybean to the application of major nutrients, and evaluate the performance of Nutrient Expert® (NE) Soybean over the existing state recommendation (SR) and the farmers' fertilizer practice (FFP). Two sets of on-station replicated experiments were conducted, one at the agricultural research station farm in Dharwad and the other at the university farm of UAS Dharwad. The study compared NE recommendation (27-51-51 kg N-P2O5-K2O/ha) with SR (40-80-25 kg/ha) and FFP (23-58-0 kg/ha), while running the omission plots for nitrogen (N), phosphorus (P), and potassium (K) from the ample NPK treatment (30-100-80 kg/ha) and an absolute control. Soybean variety JS-9305 was planted at both the locations during the monsoon season of 2016. The study also included 20 on-farm trials in the major soybean growing districts of northern Karnataka (Dharwad and Belagavi) with the comparison of three treatments of NE, SR, and FFP for yield and growth parameters of soybean.

The results from the on-station study revealed that the highest yield of soybean (3.1 t/ha) was recorded in the ample NPK treatment and the lowest yield was recorded in absolute control (1.6 t/ha). The yield due to omission of N, P, and K from the ample NPK treatment was 1.9, 2.3, and 2.4 t/ha, indicating an yield reduction of 39, 27, and 24%, respectively. The soybean yield recorded in NE and SR treatments were at par (2.9 t/ha), and 23% higher than the FFP (2.4 t/ha). In the on-farm trials, the NE-based recommendation produced average soybean yield of 2.3 t/ha that varied from 1.9 to 2.5 t/ha. The corresponding yield in SR varied from 1.9 to 2.4 t/ha with an average of 2.2 t/ha, whereas in FFP, the yield varied from 1.6 to 2.1 t/ha, with an average yield of 1.9 t/ha. The study indicated that fertilizer application as per NE resulted in almost similar soybean yield as that of SR, whereas the mean N and P2O5 rates applied in NE were lower than SR by 35 and 39%, and the K2O rates were higher than SR by 92%, respectively.

The study is a part of the development and on-farm validation of Nutrient Expert soybean, and will be continued during 2017.