Responses of soil water balance and precipitation storage efficiency to increased fertilizer application in winter wheat

Increased fertilizer use over many years may have detrimental effects on crop production due to its high soil water consumption in rainfed regions. In this study, based on a long-term fertilization experiment initiated in 1984, we report the effect of increased fertilization on soil water balance, precipitation storage efficiency (PSE), yield and water use efficiency of winter wheat from 2005 to 2009. The experimental design consisted of a control treatment (CK) and three fertilizer treatments: nitrogen, phosphorus and manure (NPM), nitrogen and phosphorus (NP), and nitrogen (N). Soil water storage in NP and NPM was significantly lower than that in CK and N at both harvest and planting time. Compared with the CK, on average, treatments N, NP and NPM increased soil water recharge during the fallow period by 11%, 22% and 17%, and they also increased soil water depletion during growing season by 17%, 23% and 23% (P<0.05), respectively. The average value of annual soil water balance was positive for all treatments, and was not significantly different among treatments. Increased fertilizer application significantly (P<0.05) increased PSE during the summer fallow periods, and the average PSE was 28%, 32%, 34% and 33% for CK, N, NP and NPM, respectively. Wheat yield and water use efficiency increased significantly after long term fertilization, especially for treatments NP and NPM. The results indicated that more of rainfall was used for evapotranspiration and less was lost during the fallow season for the high fertility treatments after long term fertilizer application. In the long run, such changes in water use pattern could help to improve the sustainability of winter wheat production.