Application of residue, inorganic fertilizer and lime affect phosphorus solubilizing microorganisms and microbial biomass under different tillage and cropping systems in a Ferralsol

Abstract Phosphorus is a critical nutrient for plant growth. Several agronomic practices have been promoted to improve soil fertility and crop productivity in Western Kenya. Yet, despite their benefits, a dearth of knowledge exists on their long-term effects on soil microbial biomass and phosphorus solubilizing microbial species (PSMs) abundance especially in this region. In a long-term (15 years) agronomic field trial, we selected 8 treatments that allowed for evaluation of 1) Effect of tillage in a maize-soybean rotation with fertilization and residue retention; 2) Effect of residue retention in a maize-soybean rotation with fertilization under conservation tillage; 3) Effect of N and P fertilization in a maize-soybean rotation with conventional tillage; 4) Effect of liming in a maize-soybean intercropping with conventional tillage; and 5) Effect of maize-soybean rotation versus intercropping under conservation tillage on microbial biomass and PSMs abundance. The study was conducted in a long-term conservation agriculture experiment (30 seasons) in a Ferralsol in Western Kenya in 2016 and 2017. Reduced tillage significantly (P