Consumption of available soil water stored at planting by winter wheat

An experiment with two water supply regimes, regime 1 (supply only by available soil water stored at planting (ASWp)) and regime 2 (supply by both precipitation (70.6 mm) and ASWp) was conducted in a winter wheat (Triticum aestivum) field at the Gucheng Agrometeorological Experimental Base of Chinese Academy of Meteorological Science from 1997 to 1999. The results indicate that under the normal ASWp condition (270–330 mm of available water) in regime 1, the consumption of ASWp lasts until the late grain filling period, and the average wheat yield is about 1160 kg hm^-2. The consumption ratios of ASWp (Rc) in the 0–50 cm layer in both regimes are over 85% due to the high root density and high evaporation in the soil profile. In the deeper portion of the soil profile (below 50 cm), Rc decreases not only with the deepening soil, but also decreases with the decrease of ASWp level resulted from the unsuccessful development of the root system. The applications of mulch, limited water stress, deep fertilization, deep tillage (to loose the plowpan) and appropriate ASWp are beneficial for winter wheat to exploit ASWp in the deeper soil profile.