One-time conventional tillage, crop diversification and mulching enhanced hydro-physical properties of a tropical sandy loam soil

Abstract

Effective soil management is crucial to sustainable crop production in the Anthropocene characterized by intensive and mechanized agrarian activities. This study analyzed integrated measures involving one-time conventional or mechanical tillage followed by no tillage and cereal-legume rotation in the context of conservation agriculture. The aim was to improve the hydro-physical properties of a sandy loam soil located in the semi-deciduous forest zone of Ghana. Twelve treatments arranged in factorial viz. (a) two levels of tillage (continuous conventional tillage of ploughing and harrowing, and one-time conventional to no tillage), (b) three levels of cropping sequence (maize monoculture, cowpea monoculture and cowpea-maize rotation) and (c) two levels of crop residue management (no mulch and mulch) were evaluated. Soil aggregate size distribution and stability, penetration resistance and some hydraulic properties, namely, saturated hydraulic conductivity, infiltration rate and sorptivity, were measured. Interaction between onetime conventional tillage and maize-cowpea rotation increased soil aggregate stability by 34%, with greater proportions in the macro aggregate size range than the interaction of same cropping sequence with continuous conventional tillage. Integrating surface mulch with tillage and maize-cowpea sequence increased mean weight diameter of water stable aggregates from 0.66 to 0.85 mm compared to similar integrated system without mulch. One-time conventional tillage increased cumulative infiltration amount by 45% and sorptivity from 7.51 to 12.24 cm h–1 over continuous conventional tillage. Generally, the interaction of one-time conventional tillage with maize-cowpea rotation or maize monoculture and mulch improved grain yield and the soil hydraulic properties of cumulative infiltration, steady state infiltrability and sorptivity. Diversifying tillage operations within the framework of conservation agriculture holds promise for improving soil hydraulic properties and crop yield in sub-Saharan Africa in the era of climate change.