| According to the field experiment in Changling County, Jilin Province, the water requirement of maize growth and the changes of water source in different years (wet year, normal year, dry year and extremely dry year) based on the same soil and farm management conditions were discussed. The results showed that water demand was different in different stages of maize growth. It reached the highest at mid-development stage, and was relatively small at early and late stage. According to the water requirement of maize growth, the test years were sequenced as: 2007(460.2 mm)＞2006(423.8 mm)＞2008(393.5 mm)＞2005(342 mm). The drier the year was, the more the total water amount and water per unit dry weight were required. The coupling degree of water requirement and effective precipitation was the highest in wet year, followed by normal year and dry year, and the lowest in extremely dry year. The soil water consumption from 2005 to 2008 was 79.8 mm, 199.1 mm, 222.7 mm and 104.6 mm, respectively. The drier the year was, the more the soil water was consumed. During the growth period
of maize, the soil water consumption was much great in July and August, thus it was necessary to increase irrigation appropriately. |