Risk management options in maize cropping systems in semi-arid areas of Southern Africa

Masvaya, E N C and Nyamangara, J and Giller, K E and Descheemaeker, K (2018) Risk management options in maize cropping systems in semi-arid areas of Southern Africa. Field Crops Research (TSI), 228. pp. 110-121. ISSN 0378-4290

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Although rainfed cropping in semi-arid areas is risky due to frequent droughts and dry spells, planting early with the first rains is often expected to result in yield benefits. We hypothesised that planting early leads to yield benefits if the planting coincides with a mineral N flush at the start of the season but leads to crop failure if there is a false start to the cropping season. The effects of different management options, including tillage (ploughing and ripping), mulch (two levels 0 and 2 t ha−1) and fertility amendments (five levels: 0; 20 and 40 kg N ha−1; 5 t manure ha−1 and 5 t ha−1 manure + 20 kg N ha−1) on grain yields were simulated using the calibrated and tested APSIM model over a 30-year period (1984–2015). Yields were simulated and compared across seven planting date scenarios (1 November, 15 November, 30 November, 15 December, 31 December, 15 January and planting when cumulative rainfall of 20 mm was received in three consecutive days). Planting with the first rains with manure + 20 kg N ha−1 resulted in the best average yield of 2271 kg ha−1 whilst the poorest average yields of 22 kg ha−1 were observed with planting on 15 January with no fertility amendment (0 kg N ha−1). Planting early (1 Nov to 15 Nov) and with the first rains resulted in exceeding the food self-sufficiency threshold of 1080 kg ha-1 in 40–83 % of the cases if fertility amendments are applied, as well as a low probability of complete crop failure, ranging from 0 to 40%. Grain yield penalties due to a false start followed the trend: ripper + mulch > plough + mulch > ripper (no mulch) averaging 256, 190 and 182 kg ha-1 respectively across all the fertility treatments. The model was able to simulate the occurrence of the mineral N flush with the first rains. Its coincidence with planting resulted in average yield benefits of 712, 452, 382 and 210 kg ha-1 for the following respective planting dates: 1 Nov, 15 Nov, 30 Nov, variable date when >20 mm rainfall was received. Early planting, in combination with reduced tillage, mulch and N containing fertility amendments is critical to reduce risk of crop failure in the smallholder cropping systems of semi-arid areas of southern Africa and achieve the best possible yields.

Item Type: Article
Divisions: Research Program : East & Southern Africa
Uncontrolled Keywords: Southern Africa, Grain requirement, N mineralisation, N stress, Water stress, Runoff curve number, maize cropping systems, smallholder cropping systems
Subjects: Others > Smallholder Farmers
Others > Soil Fertility
Others > Semi-Arid Tropics
Others > Crop Yield
Others > Cropping and Farming Systems
Others > Maize
Others > African Agriculture
Depositing User: Mr Ramesh K
Date Deposited: 10 Dec 2018 06:06
Last Modified: 10 Dec 2018 06:31
URI: http://oar.icrisat.org/id/eprint/11002
Official URL: https://doi.org/10.1016/j.fcr.2018.09.002
Funders: Netherlands Organization for International Cooperation in Higher Education (NUFFIC)
Acknowledgement: We thank the Netherlands Organization for International Cooperation in Higher Education (NUFFIC) for funding this work. We also thank the farmers Mr. and Mrs. A. Moyo in Matobo District who hosted the field trial, the resident agricultural extension officer Ms. S. Ncube who assisted in data collection and Dr. Jairos Rurinda for valuable contributions to an earlier version of this work.
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