An assessment of sustainable maize production under different management and climate scenarios for smallholder agro-ecosystems in KwaZulu-Natal, South Africa

Walker, N.J. , Schulze, R.E An assessment of sustainable maize production under different management and climate scenarios for smallholder agro-ecosystems in KwaZulu-Natal, South Africa Physics and Chemistry of the Earth Volume 31, Issue 15-16, 2006, Pages 995-1002

Abstract- The need to improve smallholder rainfed maize production in a sustainable manner is important in South Africa, as maize is a staple food to the rural indigenous population. Smallholder maize production is often characterised by low yields, which are often significantly lower than the potential for the land. However, sustainable maize production is not only a question of yields, but also of protection of the environmental resource base, social welfare, and the livelihoods of farmers as well as adjacent rural and urban communities. Sustainability for the smallholder farmer raises questions of household food security, farmer and community well-being as well as agro-ecosystem integrity. Sustainability was assessed at the smallholder agro-ecosystem scale using a goal-orientated sustainability framework. The use of the physically based CERES-Maize crop model within the sustainability framework meant that agro-ecosystem responses to different management options (e.g. tillage systems and fertiliser application) and climate change scenarios could be quantified. The agro-ecosystem that has been simulated is at Potshini village, which is about 10 km from Bergville in the western-central region of KwaZulu-Natal province, South Africa. The agro-ecosystem was simulated for different management strategies for a range of plausible future climate scenarios for South Africa. The future climate scenarios of '2 × CO2' and '2 × CO2 + 10%rain' had the biggest positive effect on mean grain yield. These scenarios had increases of over 1000 kg/ha with inorganic fertiliser and ∼200 kg/ha with manure. The largest negative effects on yield are with the '+2 °C' scenario. The biggest increase in losses of organic nitrogen were with the '2 × CO2 + 2 °C' scenario where losses increased by up to 5%.