MEASURING FOR IRRIGATION EFFICIENCY

This case study, produced by WWF South Africa in collaboration with Trace & Save, examines irrigation efficiency on six pasture-based dairy farms in the Southern Cape of South Africa. By analyzing 15 centre pivot irrigation systems between March and December 2021, the study identifies significant water wastage and explores the relationships between irrigation system variables, soil health, and water-use efficiency. It advocates for the use of water meters and scientific scheduling to reduce costs and environmental impact.

• Irrigation efficiency varies significantly across farms, with an average system efficiency of 72.2%, which is below the 'excellent' standard of 96% identified in the study. Scheduling efficiency showed a wide range from 28.9% to 166.7%, with values over 100% indicating over-irrigation.
• System efficiency is primarily driven by three factors: wind speed, the distance of the sprinkler head from the ground, and droplet size. 'Ideal' pivots—defined by wind speeds under 2 m/s, sprinkler heads at or below 1.5 m, and large or medium droplets—achieved an average system efficiency of 79%, compared to 68% for 'not ideal' pivots.
• There is a strong link between soil health and pasture water-use efficiency. Soils categorized as 'healthy' used an average of 53.08 mm of water to produce a tonne of dry matter, which is more efficient than soils of 'moderate health' or 'unhealthy' status. This is attributed to higher carbon levels and the presence of fungi, which improve soil structure and water-holding capacity.
• Inefficient irrigation leads to substantial financial and environmental opportunity costs. On average, 507,414 litres per hectare (50.7 mm) of water is wasted annually due to system inefficiencies. This wastage represents a loss of approximately 1.6 tonnes of dry matter per hectare, valued at R4,598/ha, and results in unnecessary pumping costs and CO2 emissions.
• The study found that product water-use efficiency on these farms averaged 135 litres of irrigation water to produce one litre of milk, with recorded values ranging from 23 to 253 litres.
• Several barriers hinder the adoption of efficient irrigation practices, including high infrastructure costs, lack of support from equipment providers, and regulatory frameworks. Specifically, water allocation regulations often follow a 'use it or lose it' principle, providing little incentive for farmers to save water.

APA

Phadu, L., Avidon, S., Phohlo, P., & Galloway, C. (2022). MEASURING FOR IRRIGATION EFFICIENCY. WWF South Africa. https://wwfafrica.awsassets.panda.org/downloads/measuring_for_irrigation_efficiency.pdf

Chicago

Phadu, Lorraine, Stephen Avidon, Portia Phohlo, and Craig Galloway. MEASURING FOR IRRIGATION EFFICIENCY. WWF South Africa, 2022. https://wwfafrica.awsassets.panda.org/downloads/measuring_for_irrigation_efficiency.pdf.

Wikipedia

{{cite report |last1=Phadu |first1=Lorraine |last2=Avidon |first2=Stephen |last3=Phohlo |first3=Portia |last4=Galloway |first4=Craig |title=MEASURING FOR IRRIGATION EFFICIENCY |publisher=WWF South Africa |date=2022 |url=https://wwfafrica.awsassets.panda.org/downloads/measuring_for_irrigation_efficiency.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{phadu2022measuring, author = {Phadu, Lorraine and Avidon, Stephen and Phohlo, Portia and Galloway, Craig}, title = {{MEASURING FOR IRRIGATION EFFICIENCY}}, institution = {WWF South Africa}, year = {2022}, url = {https://wwfafrica.awsassets.panda.org/downloads/measuring_for_irrigation_efficiency.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }