The soil moisture was determined gravimetrically using the oven-drying method with samples collected at a depth of 2 m and 20 cm from the middle of the furrows during sowing, jointing, the 12th leaf, tasseling, filling, and harvest stages in each crop season. The soil cores were weighed wet and dried at 105°C for 48 h. The soil water moisture was also measured in 20-22 April, 26-28 May and 7-9 July 2010, before and after rainfall.
The soil water storage in the entire 2 m soil profile was calculated using the following formula: