Effects Of Fallen Leaves In Rapeseed On Soil Nutrient Content And Microorganism Growth

By analyzing the weight and N, P and K content of fallen leaves in rapeseed in different periods and different weight of fallen leaf at different fertilization application treatments and measuring soil organic matter, total N, available N, P, K and the number of microorganisms under different weight of fallen leaf treatment. The influence of the fallen leaves on the soil nutrient content and the growth of microorganisms were studied. The main conclusions were as follows:1. With the lapse of time the weight of fallen leaf dropped unceasingly, but the decomposition rate was different in different periods. The leave decomposition rate in winter period was obviously slower than that in stem elongating stage and it decreased as the increasing of fertilizer application in different N, P and K fertilizer and increased as the increasing of fallen leaf weight. The N, P and K content in fallen leaves decreased gradually,and the decreasing rate in stem elongating stage was higher than that in winter period, and it decreased as the increasing of fallen leaf weight. The decreasing rate of N, P and K content per unit area in fallen leaves was obviously higher than that per unit weight. The order of decomposition rate of N, P and K in fallen leaves from largest to least was K>N>P.2. Soil organic matter, total N, available N, P and K increased unceasingly, and also increased as the increasing of fallen leaf weight. The increasing value at the upper 0-5cm soil was higher than that at the 15-20cm soil, but the percentage of increasing value was opposing.3. The number of bacteria and fungi in soil increased unceasingly, and also increased as the increasing of fallen leaf weight. The percentage of increasing value at the 15-20cm soil was higher than that at the upper 0-5cm. The number of bacteria and fungi in soil at the temperature of 25℃was higher than that at the temperature of 15℃.4. In the process of fallen leaves decomposition, nitrogen in the fallen leaves sent only 55 to 70 percent into the soil, including 15 to 20 percent of available N. At the same time, 25 to 35 percent of phosphorus and 55 to 60 percent of potassium changed into available P and K.