THE RELATIONSHIP BETWEEN SPECIES DIVERSITY AND NITROGEN CYCLING IN PASTURE

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The study of bio-diversity is very important for not only community ecology but also applied ecology. We want to know whether degree of bio-diversity affects efficiency of nitrogen recycling in a pasture or not. Many scientists said that there are close relationship between bio-diversity and production. If there are positive relationships between bio-diversity and production then the ecosystem of high bio-diversity have high ability of maternal recycling such as nitrogen recycling.Then we tried to know the roll of bio-diversity in pasture by two aspects such as effects of management on biodiversity, relation between bio-diversity and nitrogen recycling.Species diversities of plant and soil tick were measured by sampling data from each pasture. Nitrogen losses were calculated by nitrogen amount in milk, fertilizer and feed grains for environmental impact. To measure the efficiency of nitrogen recovery from cattle urine to grass production we used 15N marked urine in another experiment.T … More he plant diversities of low-input pastures of were higher than high-input pastures in some dairy farmers. There is strong relationship between plant and soil tick diversity. Results of Cost-benefit analysis for milk production per unit pasture show the presence of optimal-input for milk production. Many farmers will arrive to optimal point that means high efficiency of milk production. The nitrogen losses were decreased from over 80 % to 50 % during these 20 years.There is a positive relationship between efficiency of milk production per unit pasture and bio-diversity.We estimated the recovery % of nitrogen from cattle urine to grass growth using 15N-marker method ranged 37.37 % to 78.51 %. Therefore nitrogen losses were ranged 20 % to 60 %. About 20 % of nitrogen loss was derived from small amount of urine application. About 60 % of nitrogen loss was derived from large amount of urine application. This result shows the rate of nitrogen loss was affected by amount of nitrogen input.A pasture of high species diversity would have high ability of nitrogen recovery. Less