Effect of Controlled Drainage on Soil Moisture under Different Boundary Conditions

An experiment project, including field plots and test pits, had been carried out in Sihu district, Hubei province in 2010, to study the effect of controlled drainage on soil moisture. Four treatments were set up in field and test pits respectively, including free drainage (FD), and controlled drainage with drain outlet level of 30 cm, 50 cm, and 80 cm. Soil water content and ground water table were measured in the whole crop grow period. Statistic analysis and model were used to study the effect. Results showed that in test pits, controlled drainage worked obviously on soil moisture and ameliorated the soil water status effectively in the depth of 0 to 80 cm and there had a well positive correlation between controlled water table level and soil water content. Because there was little outside influence, such as lateral or groundwater recharge, the effect of controlled drainage on the soil moisture was obvious in the test pits.