Effect Of Applying Chemical Fertilizer On Community Standing Crops And Composition Of Mowing Grassland In Typical Steppe

Soil nutrient elements content were deficient seriously because of mowing year by year. Considered of this problem, the paper studied and analyzed the effect of applying chemical fertilizer on grassland in different mowing rules by designing three fertilize schemes in different mowing rules. The aim of the paper was to find out reasonable methods for managing mowing grassland.The main results as followed:(1). Standing crops of community mowed twice one year was higher hi short period. But mowing in high frequency seriously affected tall grasses, such as Stipa grandis and Leymus chinensis. The effects showed: the standing crops of tall grass decreased, their standing crops percentage in community decreased too, important value reduced, and nutrient element content was deficit, and so on. But the standing crops in control plot, which had never being mowing for several years, was not very high compared to the other plots hi different mowing rules. Comparatively, hi the mowing rules discussed hi mis paper, the reasonable one was mowing once a year. Mowing reasonably could increase the species diversity of community, but it also could reduce the content of soil available nutrient. So it is necessary to applying fertilizer artificially in mowing grassland.(2). Compared to control plot, the grassland mowed once a year could increased standing crops by 50% in the year applying urea fertilizer 140kg/hm2, and increased by 30% the next year; applying phosphorus diamine fertilizer 80 kg/hm2 could increase standing crops by 25%, and 20% the next year; applying potassium sulfate compound fertilizer 120 kg/hm2 could increase standing crops by 45%, and 25% the next year. From the economic benefits, applying urea fertilizer was best in the three fertilizers, and applying phosphorus diamine fertilizer was worst. The profits in that year made by three fertilizers applied were 209.65/hm2, 15.95/hm2 , and 149.957 hm2 from urea fertilizer, phosphorus diamine fertilizer, and potassium sulfate compound fertilizer respectively. The profits in two years were 447.00/hm2 , 141.05/hm2 , and 330.50/hm2 from urea fertilizer, phosphorus diamine fertilizer, and potassium sulfate compound fertilizer respectively.(3). After fertilizing, L. chinensis and S.grandis both showed equal-compensation and over-compensation phenomenon in grassland of mowing once a year. The over-compensation of Cleistogenes squarrosa was more obvious. As for L. chinensis, the effect of three fertilizers on its standing crops was: urea fertilizer, potassium sulfate compound fertilizer, and phosphorus diaminefertilizer, with sequence from large to small. As for S.grandis, the effect of three fertilizers on its standing crops was: urea fertilizer, phosphorus diamine fertilizer, and potassium sulfate compound fertilizer, with sequence from large to small. The effect of urea fertilizer and phosphorus diamine fertilizer on S.grandis was similar. As for C. squarrosa, the effect of three fertilizers on its standing crops was: urea fertilizer, potassium sulfate compound fertilizer, and phosphorus diamine fertilizer with sequence. The effect of urea fertilizer and potassium sulfate compound fertilizer on C. squarrosa was similar.Applying urea fertilizer could increase the nitrogen content of the three plants: L.chinensis, S.grandis, and C.squarrosa, and its effect was more obviously titan applying the other fertilizers. At the same time, applying urea fertilizer could decrease the phosphorus content of the three plants. In the grassland of mowing once a year, applying potassium sulfate compound fertilizer could increase nitrogen content of L.chinensis and S.grandis more than applying phosphorus diamine fertilizer. In the grassland of control plot, effects of the two fertilizers were contrary. The effect of the two fertilizers on nitrogen content and phosphorus content of C. squarrosa had no difference. The effects of three fertilizers on the potassium content of three plants were small.(4). As for rhizome grass, the effect of three fertilizers on its standing crops was...