The impact of biochar, lime and fertilizer on soil acidity and microbiological properties and their relationship with yield of rice and cowpea in an acidic soil of Southern India.

A field experiment was conducted at Zonal Agricultural Research Station, Mandya to evaluate the effect of biochar, lime and fertilizer on soil acidity and microbiological properties in an acidic soil. The experiment was laid out in randomized complete block design with seven treatments and three replications. The results revealed that application of fertilizer based on the soil test value (STV) either in combination with biochar or lime influenced soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), dehydrogenase, urease and phosphatase activities significantly. Similarly, application of STV-based fertilizer along with biochar+FYM (Farm Yard Manure) + ZnSO4 significantly decreased exchangeable aluminum, exchangeable acidity and total acidity as compared with recommended dose of fertilizer (RDF) + FYM+ ZnSO4 treatment. The grain yield of rice was increased by 37.90% in STV + biochar + FYM + ZnSO4 and by 22.87% in STV + lime +FYM + ZnSO4 plots than RDF + FYM + ZnSO4 plot. Seed and haulm yield of cowpea increased by 33.57% and 18.53% in STV + biochar + FYM + ZnSO4 treatments as compared with RDF + FYM + ZnSO4 treatment. Exchangeable aluminum and exchangeable acidity were found to be negatively correlated with yield of rice (r = -0.179) and cowpea (r = -0.266). However, yield of rice and cowpea showed the significantly and positively correlated with microbiological properties. The exchangeable Al and exchangeable acidity were found to be negatively correlated with SMBC, SMBN, dehydrogenase activity, urease activity and phosphatase activity. [ABSTRACT FROM AUTHOR]