Options Winter 2021: Water scarcity and rising fertilizer prices are causing complications for sustainable agriculture in South Africa. IIASA researchers have validated and calibrated models to help address the issue. 

Sustainable agriculture is a challenge for much of the world. Nowhere is this challenge more pressing than in South Africa. In fact, growing water scarcity, coupled with rising fertilizer (Nitrogen) prices, are causing new complications for this already fraught situation. The most realistic solution to this problem is better management of both fertilizer and water usage. A study by IIASA researchers Stephan Pietsch from the Advancing Systems Analysis Program and Juraj Balkovic from the Biodiversity and Natural Resources Program, set out to help address this problem by exploring models for potential improvements.

The researchers used a calibrated and validated Environmental Policy Integrated Climate (EPIC) model to simulate a range of Nitrogen and irrigation water levels on maize yield in South Africa’s Eastern Cape. Their results show that the highest average maize yield was produced by utilizing 155 kg of nitrogen and 600 mm of water. This number represents a 69% increase over the average farmer’s maize yield. The results confirm the importance of proper management practices.

“If the goal is sustainable agricultural intensification, then the solution must involve developing effective, location-specific agricultural land management strategies,” explains Pietsch. “We must balance increased crop productivity with minimal negative environmental impact. The EPIC model can be used as a valuable tool in identifying optimal, site-specific irrigation water and proper application levels of Nitrogen fertilizer. This will not only increase maize crop productivity, but also maximize water use.”

By Jeremy Summers