Changes of Soil Conditions and Maize Yield After Years of Conventional Tillage on a Mollic Soil

Abstract

Soil tillage affects soil physical, biological and nutrient cycling capacity. Field studies were conducted from 2016 to 2018 on same site using two tillage systems Conventional and Reduced tillage. Conventional tillage was done using a 3-disc plough while reduced tillage was done using a Chisel plough. The objective of this study was to evaluate changes in some soil properties induced by two different tillage treatments and their effect on maize grain yield. The trial was set at Kenya Agricultural Livestock & Research Organization (KALRO) Njoro on a Mollic Andosol. The design was randomised complete block replicated four times. The factor tillage had two levels. Changes in water stable aggregates, compaction as measured by changes in bulk density, soil water retention at pF 4.2, total soil organic carbon and hence soil organic matter, microbial biomass [bacteria and fungi] in form of total microbial biomass-N and microbial biomass-C and maize yield were obtained after three years in 2018. With exception of bulk density that was found to be higher in Conventional tillage, results showed that aggregate stability water stable aggregates, soil water retention capacity at pF4.2, soil organic matter. Total microbial biomass-nitrogen and microbial biomass-carbon were higher in reduced tillage. Maize grain yield was higher (p<0.05) in reduced tillage. Bulk density of the soil was observed to be higher after three years of conventional tillage compared to reduced tillage. Reduced tillage increased soil organic matter, structure, water retention and microbial biomass and maize yields. This study has revealed that reduced tillage is pivotal in healing the highly weathered soils that have become degraded and soil fertility has declined through decades of continuous disc and plough tillage, lengthy exploitation and nutrient mining leading to low crop yields.