MEASURING FOR IRRIGATION EFFICIENCY

The study analysed 15 centre pivot irrigation systems on six dairy farms in South Africa's Southern Cape between March and December 2021. It found that average system efficiency was 72.2%, with significant water wastage driven by wind speed, sprinkler height, and droplet size. The research highlights a positive correlation between soil health—specifically higher carbon and fungi levels—and pasture water-use efficiency. Financial analysis indicates that inefficient irrigation leads to substantial opportunity costs in terms of wasted water, increased electricity bills, and lost potential for dry matter production. The document advocates for the use of water meters and precise scheduling to reduce costs and enhance agro-ecosystem services.

• Average system efficiency across the 15 analysed pivots was 72.2%, which is below the 'excellent' standard of 96% identified in the study. Scheduling efficiency showed a wide variance, ranging from a minimum of 28.9% to a maximum of 166.7%, with values over 100% indicating over-irrigation.
• Three primary biophysical factors significantly impact system efficiency: wind speed (the most influential), the distance of the sprinkler head from the ground, and droplet size. 'Ideal' pivots—defined by wind speeds below 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 direct relationship between soil health and pasture water-use efficiency. Soils categorised as 'healthy' used an average of 53.08 mm of water to produce a tonne of dry matter, performing more efficiently than soils of 'moderate health' or 'unhealthy' status. This is linked to higher total and active carbon and the presence of fungi, which improve soil structure and water-holding capacity.
• Inefficient irrigation results in significant economic and environmental opportunity costs. On average, 507,414 litres per hectare (50.7 mm) of water is potentially wasted annually. This wastage equates to a loss of approximately 1.6 tonnes of dry matter per hectare, valued at R4,598/ha, and results in an average of 17.38 extra pumping hours per hectare per year.
• The adoption of best-management practices for water efficiency is hindered by several obstacles, 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} }