Water losses, distribution, and use under a center-pivot irrigation system
de Jong, E.
Peer Reviewed StatusNon-Peer Reviewed
MetadataShow full item record
A study was conducted to quantify the water losses that occur under center pivot irrigation. Spray and drift losses were calculated as the difference between the amount of water applied, as measured by a flow meter attached to the mainline pipe, and the amount of water collected by a network of rain gauges located just above the crop canopy. Evapotranspiration from durum was measured directly using an energy balance/Bowen ratio system. Spray and drift losses at times exceeded 49 % of the water applied. The mean loss over the 1988 growing season was 29 %. The extent of the loss was highly dependent on the wind speed, wind direction relative to the sprinkler lateral and the vapour pressure deficit. Distribution of water across the field was extremely variable and again highly dependent on wind speed and direction. At times 93 % of applied water was lost within 24 hours of application with daily evapotranspiration exceeding 14 mm. Evaporation rates were often significantly increased by advective energy so that latent energy flux densities exceeded net radiation by up to 30 %. In most cases evaporation became soil limited within three days of irrigation, despite the fact that for most of the growing season soil water content in the 50-180 cm soil layer was seldom less than field capacity. Neutron probe data indicated that there was little uptake of water in this layer.
Part OfSoils and Crops Workshop
The following license files are associated with this item: