Large-scale demo plot trial project of potash fertilization for increased yield and profitability for smallholder soybean fields in India

The paper, “Large-scale demo plot trial project of potash fertilization for increased yield and profitability for smallholder soybean fields in India” was published in International Journal of Agricultural Extension 7(02):159-170, 2019. Authored by Joachim B. Nachmansohn, Patricia Imas, and Surinder K. Bansal, the research (part of the ‘Potash for Life’ project) summarizes the results from field demonstrations of the response of soybean to potash fertilizer application.

Abstract

Agriculture is the backbone of the Indian economy, in spite of concerned efforts towards industrialization in the last three decades. Therefore, the soil quality and fertility are the major factors in crop production. Declining soil fertility is one of the primary factors that directly affect crop productivity, and fertilizer-use is a key factor in order to keep soil fertility and productivity. A major factor in declining soil fertility is potassium (K) depletion, especially on smallholder farms where fertilization decisions are not based on regular soil testing. Most of the smallholder soybean producers do not have access and investment capacity to soil testing services. Therefore, there is a need to create K fertilizer recommendations based on empirically verified knowledge at India-specific scale. Such large-scale studies, in local filed conditions, are currently lacking. In order to bridge this gap, and generate proven set of directly applicable recommendations, a large-scale plot trial was launched; the Potash for Life (PFL) project. The study evaluated the K response in soybean when fertilizing with potash on K depleted soils in local variable field conditions. The aim was to (1) evaluate the effect and response consistency of K application on soybean yield, (2) to demonstrate to farmers the increased yield and profitability from K-inclusive fertilization regimes for this crop and give recommendations for transient yield increase, and (3) to raise the awareness among smallholder farmers about the importance of K fertilization. A comprehensive experiment was carried out in Madhya Pradesh (M.P.) and Maharashtra. The methodology was straight-forward; two identical plots side by side, with the only difference that one of them was fertilized with additional potash. The results showed a significant yield increase response from the potash application; the average yield increase was 244 kg ha^-1 or 26 % in M.P., and 105 kg ha^-1 or 36 % in Maharashtra. This entailed an average additional net profit of ₹6,681 INR ha^-1 and ₹2,544 INR ha^-1, in M.P. and Maharashtra respectively. It was concluded that the soil status of plant available K is significantly lower than the plant demand for soybean production in the two states, Consequently, K fertilization is necessary in order to improve agricultural practices and optimizing yields. Ultimately, following recommendations given in this study would allow farmers to generate additional profit, which could further allow them to invest in fine-tuning fertilizer practices through the means of soil testing.

Keywords: Soil-fertility, Potassium, Fertilizer, Yield increase, Fertilizer-use, Madhya Pradesh, Maharashtra.