Soil water distribution, uniformity and water-use efficiency under alternate furrow irrigation in arid areas

Soil water distribution, irrigation water advance and uniformity, yield pro duction and water-use efficiency (WUE) were tested with a new irrigation me thod for irrigated maize in an arid area with seasonal rainfall of 77.5-88. 0 mm for 2 years (1997 and 1998). Irrigation was applied through furrows in three ways: alternate furrow irrigation (AFI), fixed furrow irrigation (FF I) and conventional furrow irrigation (CFI). AFI means that one of the two neighboring furrows was alternately irrigated during consecutive watering. FFI means that irrigation was fixed to one of the two neighboring furrows. CFI was the conventional method where every furrow was irrigated during eac h watering. Each irrigation method was further divided into three treatment s using different irrigation amounts: i.e. 45, 30, and 22.5 mm water for ea ch watering. Results showed that the soil water contents in the two neighbo ring furrows of AFI remained different until the next irrigation with a hig her water content in the previously irrigated furrow. Infiltration in CFI w as deeper than that in AFI and FFI. The time of water advance did not diffe r between AFI, FFI and CFI at all distances monitored, and water advanced a t a similar rate in all the treatments. The Christiansen uniformity coeffic ient of water content in the soil (CUs) was used to evaluate the uniformity of irrigated water distribution and showed no decrease in AFI and FFI, alt hough irrigation water use was smaller than in CFI. Root development was si gnificantly enhanced by AFI treatment. Primary root numbers, total root dry weight and root density were all higher in AFI than in the FFI and CFI tre atments. Less irrigation significantly reduced the total root dry weight an d plant height in both the FFI and CFI treatments but this was less substan tial with AFI treatments. The most surprising result was that AFI maintaine d high grain yield with up to a 50% reduction in irrigation amount, while t he FFI and CFI treatments all showed a substantial decrease of yield with r educed irrigation. As a result, WUE for irrigated water was substantially i ncreased. We conclude that AFI is an effective water-saving irrigation meth od in arid areas where maize production relies heavily on repeated irrigati on.