Performance of simple irrigation scheduling calendars based on average weather data for annual ryegrass

• Published in: African journal of range & forage science Vol. 31; no. 3; pp. 221 - 228
• Main Authors: Fessehazion, Melake K, Annandale, John G, Everson, Colin S, Stirzaker, Richard J, van der Laan, Michael, Truter, Wayne F, Abraha, Amanuel B
• Format: Journal Article
• Language: English
• Published: Scottsville Taylor & Francis 02.09.2014; Taylor & Francis Ltd
• Subjects: consultants; Farmers; forage and feed science; income; Irrigation; Irrigation scheduling; Irrigation water; Leaching; Lolium; meteorological data; Moisture content; nitrate fertilizers; nutrient use efficiency; Pasture; pastures; planted pastures; site-specific irrigation calendar; Soil water; soil water balance; soil water balance model; Water availability; Water balance; Water management; water requirement; Water use; Africa
• DOI: 10.2989/10220119.2014.906504
• ISSN: 1727-9380; 1022-0119

Poor irrigation management in pastures can lead to yield and quality reduction as well as loss of income through extra pumping and leaching of nitrate fertiliser. A number of irrigation scheduling techniques of varying levels of sophistication have been developed over the years to address limited irrigation water availability and maximise productivity. Despite this, the adoption of irrigation scheduling tools by farmers remains low. The objective of this study was to assess the use of simple irrigation scheduling calendars based on average weather data to improve irrigation management in ryegrass. The calibrated Soil Water Balance (SWB) model was used to generate simple irrigation calendars and assess effectiveness for different scenarios by mechanistically simulating water dynamics and pasture growth. Scheduling irrigation using the calendars gave similar irrigation applications, water losses and yields compared to a more scientific real-time scheduling (in response to soil water depletion by the crop). While site-specific irrigation scheduling calendars can easily be generated by consultants and irrigators, even simpler monthly estimates of average daily water use can also be useful. Application of calendars by farmers is encouraged to improve water and nutrient use efficiency of irrigated pastures, if real-time irrigation scheduling is not employed.