A meta-analysis of long-term effects of conservation agriculture on maize grain yield under rain-fed conditions

Summary

This meta-analysis of long-term rain-fed maize experiments in Southern Africa synthesises evidence on conservation agriculture effectiveness across contrasting conditions. The findings reveal that conservation agriculture benefits are context-dependent: yield improvements occur in low-rainfall areas with rotation and high inputs, whilst mulch cover in high-rainfall zones reduces yields due to waterlogging, and adequate soil drainage and nitrogen availability are critical success factors. Rainfall emerges as the dominant determinant of yield outcome across the region.

Regional applicability

Southern Africa focus limits direct applicability to United Kingdom, which has different agroclimatic conditions, higher baseline rainfall, and established soil management practices. However, the meta-analytical approach to contextualising conservation agriculture benefits across soil and climate gradients may inform similar sensitivity analyses for UK farming systems, particularly regarding residue management timing and nitrogen release dynamics.

Key measures

Maize grain yield (t/ha), yield stability, temporal yield trends, soil texture effects, nitrogen input requirements, rainfall patterns, mulch cover effects

Outcomes reported

The meta-analysis examined maize grain yield responses to conservation agriculture practices (reduced tillage, residue retention, crop rotation) over 5+ years under rain-fed conditions, assessing effects across varying soil textures, nitrogen inputs, and climate zones. Yield variability and stability were measured through temporal analysis and stability metrics.

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