The region has a typical temperate continental monsoon climate. The mean annual temperature is 4.4 C. The mean annual precipitation is 520 mm and more than 70% of precipitation occurs from June to August. The average annual potential evapotranspiration is 1009 mm (1971–2000) and markedly exceeds annual precipitation. The soil is a typical black soil (Typic Hapludoll, USDA, 1993) with a clay loam texture consisting of 36.0% clay, 24.5% silt and 39.5% sand. Prior to the initiate of the tillage trials, the field had been used for continuous maize (Zea mays L.) with conventional tillage for more than 20 years (Liang et al., 2007).