Effect of Various Mulching Durations with Plastic Film on Soil Microbial Quantity and Plant Nutrients of Spring Wheat Field in Semi-arid Loess Plateau of China
覆膜对春小麦农田微生物数量和土壤养分的影响

Effect of various mulching durations with plastic film on soil microbial quantity and plant nutrients of the spring wheat field was investigated in semi\|arid Loess Plateau of northwest China for two years. Four treatments were employed: M 0\|no mulching, M 30 \|mulching for 30 days from sowing, M 60 \|mulching for 60 days, and M\|mulching for whole growth period. In 1999, a wet year with rich precipitation, the total soil microbial quantity increased faster and the higher level of soil microbial q...