Effect of Manure Management on the Temporal Variations of Dryland Soil Moisture and Water Use Efficiency of Maize

Degraded soils in Northwest China are mostly nonproductive due to imbalanced nutrient and inadequate water supply. The effects of manure application at three different rates (7.5, 15.0, and 22.5 t ha(-1)) combined with chemical fertilizers on soil water and Water-Use Efficiency in maize [compared with chemical fertilizers (control)], under semi-arid conditions in dark Loessial soil and over a period of four years were studied to provide scientific support for water management. High manure application significantly reduced soil water evaporation throughout the fallow period as compared with control. It significantly increased soil water storage capacity at the big trumpet growth stage of the crop, and with the fertilization application years continued (P<0.05). Manure application improved soil water holding capacity at the tasseling and grain filling stages. It decreased evapotranspiration at the jointing-big trumpet and tasseling-grain filling stages. It as well improved Water-Use Efficiency by 16.67 to 295.42% at the jointing-big trumpet stage vs. 9.38-68.96% at the tasseling-grain filling stage and 8.51 to 36.58% for the whole growth period of the crop maize. With a continuation of the fertilizer application years, water-use efficiency at the tasseling-grain filling stage was significantly improved with increasing manure application rates (P<0.05). Medium and High Manure application rates significantly increased water-use efficiency at the big trumpet-tasseling and grain filling-maturity stages as compared with control (P<0.05). With manure application years continued, soil nutrient was no longer the major factor limiting the crop's water-use efficiency. The most promising manure application rate adopted to improve water-use efficiency was recorded as 15.0 t ha(-1).