Impact of irrigation variability on pasture production and beneficial water use.

Book Title: NA
Year Published: 2007
Month Published: NA
Author: Snow, V. O. ; Zyskowski, R. F. ; Martin, R. J. ; Knight,T. L. ; Gillespie, R. N. ; Riddle, M. U. ; Fraser, T. J. ; Thomas, S. M.
Book Group Author: NA

As the availability of water for irrigation becomes more limiting it is important to use the available water effectively and all potential avenues for improving irrigation efficiency should be examined. Improving irrigation system uniformity can lead to production gains and less loss of water through drainage, but such data are difficult to collect experimentally. Here we examine the potential of using a pasture production model to explore the gains from increased irrigation evenness and different irrigation scheduling. Simulations were done with varying levels of irrigation inputs to account for spatial and temporal variability of irrigation but with the same total amount of water being applied to the paddock. All simulations were done under the assumption of no nitrogen limitation to growth and with soil and weather data appropriate for the Winchmore area. There was a relatively greater effect of irrigation uniformity on drainage than on pasture production. In reality uneven irrigation may lead to areas of the paddock where over-irrigation leaches nitrogen from the soil and pasture production becomes limited by nitrogen supply. The simulation results here were under the assumption of non-limiting nitrogen and it is likely that inclusion of a full nitrogen simulation would lead to different results. However the model shows potential for generating data needed to understand the benefits of improved irrigation uniformity.

Pages: 59 - 64
Volume: 69
Number: NA
Journal: Proceedings of the New Zealand Grassland Association
Journal ISO: NA
Organization: NA
Publisher: NA
ISSN: 0369-3902

drainage, irrigation, irrigation scheduling, irrigationsystems, leaching, nitrogen, paddocks, pastures, spatial variation,temporal variation, water use, water use efficiency, New Zealand,Australasia, Oceania, Developed Countries, Commonwealth of Nations, OECDCountries, grazing lands, watering, Soil Chemistry and Mineralogy(JJ200), Soil Water Management (Irrigation and Drainage) (JJ800)(Revised June 2002) [formerly Soil Water Management], Grasslands andRangelands (PP350)

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