Effects of nitrogen and phosphorus on dry farming spring corn yield and water use efficiency under different tillage practices

A six-year experiment (2003 to 2008) was conducted in Shouyang Dryland Farming Experimental Station in Shanxi Province to study the effect of different tillage practices (no-tillage, reduced tillage and conventional tillage) with three nitrogen (N) and phosphorus (P2O5) fertilizer rates (105, 179 and 210 kg/hm2; N:P2O5 =1:1) on spring corn yield and water use efficiency. The results showed that at the recommended fertilizer rate of 105 kg/hm2, the average yield and water use efficiency (WUE) were about 5 234 kg/hm2 and 12.4 kg/(hm2·mm), respectively, under conventional tillage (CT), and about 5 751 kg/hm2 and 13.6 kg/(hm2·mm), respectively, under reduced tillage (RT). The average yield and WUE under RT increased by about 9.9% and 9.7%, respectively, compared to CT. Under no-tillage (NT), the average yield and WUE, at the fertilizer rate of 179 kg/hm2, were highest, about 5 336 kg/hm2 and 13.2 kg/(hm2·mm), respectively, which were about 6.1% and 9.7% higher than those under CT. The NT increased soil water contents, resulting in higher yields in dry years, compared to CT. Among three tillage practices, the average yield and WUE were ranked as RT >NT >CT.