Effects of Tillage Systems and Organic Amendments on Nitrogen Mineralisation and Soil Erodibility in a Tropical Alfisol

Abstract

Tropical soils are inherently low in fertility and highly susceptible to erosion, hence affecting crop productivity. Few studies have examined the effect of biochar from different sources and cow dung compost on tropical soils. This study assessed the influence of compost and biochar produced from cow dung and maize cobs on the physical and chemical properties of Alfisols. It investigated their mineralisation rates and the influence on the soil erodibility when these organic amendments are applied under different tillage practices. The experiment was laid out in a randomised complete block design during the 2018 wet and dry seasons. Soil amendments were 100% cow dung compost (A100), 100% cow dung biochar (B100), 50% cow dung compost and 50% cow dung biochar (AB50), and a combination of the three amendments, i.e., cow dung biochar, cow dung compost, and maize cobs biochar at 33% each (C33), and a control (D). Amendments were applied at 4 t ha-1. Soils treated with B100 and A100 under conventional tillage had the highest total nitrogen and available phosphorus values of 3.92 g/kg and 10.37 mg/kg, respectively. The highest mineralisation rate was observed in soils treated with A100, with 142.87 μgNg-1 under conventionally tilled soils. However, erodibility rate was lower under minimum tillage, with C33 having the lowest at 0.35. The results suggest that the combined application of cow dung and biochar under conventional tillage can improve soil fertility in the short term; however, minimum tillage would be a preferable alternative for long-term soil health and productivity.