Original Articles

Effects of level and timing of irrigation on growth and water use of lucerne

Published in: South African Journal of Plant and Soil
Volume 2, issue 4, 1985 , pages: 197–202
DOI: 10.1080/02571862.1985.10634169
Author(s): D.J. BeukesDepartment of Agriculture and Water Supply,, S.A. BarnardDepartment of Agriculture and Water Supply,

Abstract

A six-year flood irrigation trial with lucerne (Medicago sativa cv. Karoo) was conducted on a sandy loam soil in the south-western part of the Cape Province at Oudtshoorn. Two cropping practices, whereby one or two forage cuttings are followed by a seeding period, were investigated. The treatments comprised the application of 90, 135 and 180 mm (50–100% PAW) of water, as well as the same amounts, but in two equal parts, during a production period. Seasonal évapotranspiration (ET) varied from 382 to 668 mm, depending on the amount of irrigation per application. The halving of applications and doubling of irrigation frequency, did not increase ET above that of the full applications. Mean seasonal crop factors (ET/Ep) ranged from 0,40 to 0,70 for different levels of irrigation with a peak of 0,99 during the first forage period for a 180 mm application. Forage yields per unit area increased with an increase in irrigation level. The halving of applications also led to an increase in yield. Larger forage yields were obtained during the second than during the first production period. Growth rate of lucerne was enhanced remarkably at high irrigation levels, or when half-quantity irrigations at double the frequency were applied. Water use efficiency was highest for those treatments comprising of the smallest applications and the highest irrigation frequency. Seed yield was higher when less water was applied. Seed production was also increased when irrigation was applied in two parts.

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