Impacts of manure application on soil environment, rainfall use efficiency and crop biomass under dryland farming

Because of inadequate nutrient and water supply, soils are often unproductive in Northwest China. We studied the effects of manure application at low (LM 7.5 t ha(-1)), medium (MM 15 t ha(-1)), and high (HM 22.5 t ha(-1)) rates combined with fixed levels of chemical fertilizers on maize growth and rainfall use efficiency compared with chemical fertilizers (CK) under semi-arid conditions over a three-year period. HM and MM treatments could significantly increase soil water storage (0-120 cm) at tasseling stage of maize compared with LM treatment and CK (P < 0.05). Dry matter accumulation and rainfall use efficiency increased as manure application rate increasing (P < 0.05). HM treatment significantly increased rainfall use efficiency by 6.5-12.7% at big trumpeting - tasseling stage compared with LM and MM treatments. HM and MM treatments increased rainfall use efficiency by 8.6-18.1% at tasseling grain filling stage compared with CK. There was no significant difference on biomass between HM and MM treatments at grain filling and maturity stages of maize in 2009 and 2010.