Effect of biochar, lime and soil test value based fertilizer application on soil fertility, nutrient uptake and yield of rice-cowpea cropping system in an acid soil of Karnataka.

A field experiment was conducted during Kharif and Summer seasons for two consecutive years of 2016-17 and 2017-18 with rice (Oryza sativa L.) and cowpea (Vigna unguiculata L.), grown in a sequence at Zonal Agricultural Research Station, Mandya on an acid soil to study the effect of biochar, lime and mangala setright on yield, nutrient uptake and fertility status of an acidic soil. Application of biochar along with soil test value based fertilizer (STV) + FYM + ZnSO4 influenced the productivity of rice and cowpea of 104.82 q ha−1 and 2474.77 kg ha−1, respectively and the uptake of nitrogen, phosphorus and potassium by rice (107.72, 28.16 and 69.34 kg ha−1, respectively) and cowpea (68.06, 5.86 and 38.67 kg ha−1, respectively) significantly, which was found on par with application of biochar along with RDF + FYM + ZnSO4. The soil pH (6.01), organic carbon content (5.03 g kg−1) and available nitrogen (340.45 kg ha−1), phosphorus (39.45 kg ha−1) and potassium (166.45 kg ha−1) significantly increased through the integrated use of biochar, FYM, ZnSO4 and fertilizers. Yield and soil properties like soil pH, organic carbon content and available nitrogen, phosphorus and potassium significantly increased with application of lime and mangala setright as compared to farmer's practice. Highest net income and benefit:cost ratio (2.65) was obtained with integration of soil test value based fertilizer application, FYM and biochar. Significant reduction in the productivity of crop and soil fertility was recorded in farmer's practice. [ABSTRACT FROM AUTHOR]