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

Rusinamhodzi, L and Corbeels, M and Wijk, M T Van and Rufino, M C and Nyamangara, J and Giller, K E (2011) A meta-analysis of long-term effects of conservation agriculture on maize grain yield under rain-fed conditions. Agronomy for Sustainable Development, 31 (4). pp. 657-673. ISSN 1774-0746

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Conservation agriculture involves reduced tillage, permanent soil cover and crop rotations to enhance soil fertility and to supply food from a dwindling land resource. Recently, conservation agriculture has been promoted in Southern Africa, mainly for maize-based farming systems. However, maize yields under rain-fed conditions are often variable. There is therefore a need to identify factors that influence crop yield under conservation agriculture and rain-fed conditions. Here, we studied maize grain yield data from experiments lasting 5 years and more under rain-fed conditions. We assessed the effect of long-term tillage and residue retention on maize grain yield under contrasting soil textures, nitrogen input and climate. Yield variability was measured by stability analysis. Our results show an increase in maize yield over time with conservation agriculture practices that include rotation and high input use in low rainfall areas. But we observed no difference in system stability under those conditions. We observed a strong relationship between maize grain yield and annual rainfall. Our meta-analysis gave the following findings: (1) 92% of the data show that mulch cover in high rainfall areas leads to lower yields due to waterlogging; (2) 85% of data show that soil texture is important in the temporal development of conservation agriculture effects, improved yields are likely on well-drained soils; (3) 73% of the data show that conservation agriculture practices require high inputs especially N for improved yield; (4) 63% of data show that increased yields are obtained with rotation but calculations often do not include the variations in rainfall within and between seasons; (5) 56% of the data show that reduced tillage with no mulch cover leads to lower yields in semi-arid areas; and (6) when adequate fertiliser is available, rainfall is the most important determinant of yield in southern Africa. It is clear from our results that conservation agriculture needs to be targeted and adapted to specific biophysical conditions for improved impact.

Item Type: Article
Uncontrolled Keywords: Conservation agriculture – Maize grain yield – Meta-analysis – Stability analysis – Rain-fed conditions – Southern Africa
Subjects: Others > Agriculture-Farming, Production, Technology, Economics
Depositing User: Users 6 not found.
Date Deposited: 05 Dec 2011 05:02
Last Modified: 03 May 2013 05:06
URI: http://oar.icrisat.org/id/eprint/4780
Official URL: http://dx.doi.org/10.1007/s13593-011-0040-2
Projects: CA2Africa Project
Funders: European Commission
Acknowledgement: We are most grateful and indebted to a number of authors, and we would like to make a special mention to Professor Waren A. Dick, Nithya Janakiraman, Sindhu Jagadamma and Adelaide Moyo-Munodawafa for making available raw data from their longterm studies. Financial support from TSBF-CIAT Harare through the Sub-Saharan Challenge Program’s Conservation Agriculture Taskforce grant is greatly appreciated. Marc Corbeels acknowledges financial support from the European Commission through the CA2Africa Project.
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