Effects of tillage on runoff from a bare clayey soil on a semi-arid ecotope in the Limpopo Province of South Africa

J Mzezewa,LD Van Rensburg

doi:10.4314/wsa.v37i2.65862

Abstract

Runoff constitutes one of the major water losses from agricultural fields in semi-arid areas. However, by adopting appropriate soil management practices, the runoff can be harnessed for improving crop yields. The main objective of this study was to quantify rainfall-runoff relationships under in-field rainwater harvesting (IRWH) using simulated rainfall, and to compare these results to those obtained with annually tilled conventional tillage (CON) (control). IRWH is a special type of no-till (NT) crop production practice that promotes runoff from a crusted runoff strip into basins where the water infiltrates beyond evaporation but is available for crop use. Runoff was related to time to runoff, total runoff, final runoff rate and runoff coefficient. This experiment demonstrated that by adopting IRWH production technique smallholder farmers could harness an additional 45.54 m3·ha-1 of water compared to the CON system. The extra water harvested could meet about 1% of maize water requirements.

Highlights

Water scarcity is a major constraint in semi-arid areas, leading to a natural focus on in-field rainwater conservation (Jensen et al, 2003)
Short runoff time is beneficial for water harvesting especially on the study site where most of the rainfall comes in light showers (Mzezewa et al, 2010)
Higher total runoff under in-field rainwater harvesting (IRWH) treatment was attributed to low surface roughness (10 mm) on IRWH plots compared to conventional tillage (CON) (29 mm)

Summary

Introduction

Water scarcity is a major constraint in semi-arid areas, leading to a natural focus on in-field rainwater conservation (Jensen et al, 2003). Runoff constitutes one of the major water losses in semi-arid areas, causing the loss of valuable water, soil and nutrients (Schiettecatte et al, 2005; Vahabi and Mahdian, 2008). Among the various water harvesting technologies available, in-field rainwater harvesting (IRWH) has been shown to be an efficient water conservation crop production technique especially appropriate for rural poor households (Botha et al, 2003).

Objectives

Methods

Results

Conclusion