Cultivated rice is a heavy consumer of fresh water. Approximately 50% of the fresh water used in Asian agriculture goes to rice production. Traditional lowland rice with continuous flooding has relatively high water inputs and its sustainability is now being threatened with increasing water shortage. Water savings and "producing more rice with less water" are crucial to food security in China. Plastic film mulching cultivation of dryland rice has been reported to use only 40% of the amount of water usually needed to grow rice in submerged conditions. Grain yields remained at 90% of those of high-yielding submerged systems (Peng et al 1999). A recent study of film mulching on upland cultivated rice focused on the changes in plant morphology and yield, cultivation techniques, water-saving effects, and nutrient use (Liang et al 1999, Cheng et al 2003). The aim of this study was to examine the effects of film mulching on soil microbial amount and enzyme activities.
Rice cultivar Yue-Xiang-Zhan was used in the experiment conducted in the early and late season of 2002. It was laid out using a random complete block design with three replications in Guangzhou. Three treatments were used: T1 = rice cultivated under aerobic conditions; T2 = rice cultivated under aerobic conditions, covered by plastic film; and T3 (check) = traditional rice production. All 32-m2 plots were enclosed by dams 50 cm wide and 15 cm high to ensure independent hydrological conditions. Except for traditional rice production, for the T2 and T3 treatments, the field was not irrigated only at transplanting time (1 wk after transplanting); the remaining growth stages completely depended on rainfall.