The Environmental Characteristics Of Nitrogen And Phosphorus In The Soils From The Farmlands Tilled Under Different Time-lasting Greenhouse

Based on the Chai River catchment in Dianchi watershed the Soils from the greenhoused farmland(GF)under Different lasting Time and natural farmland(NF) as the research object, through the investigation of management in the soils GF and NF, the content of nitrogen and phosphorus changing in underground water-soil-crop compound system as well as nitrification rates, denitrification rate, respiratory rate in soil were obtained to explore the environmental behavior of nitrogen and phosphorus in the soils from GF and NF including nitrogen and phosphorus transport, distribution and loss of status, to preliminary quantitative the loss of nitrogen and phosphorus under different case. The main results of this research are as follows.(1) The average total nitrogen of4-year greenhouse farming layer was3.63g/kg, the average total phosphorus was1.95g/kg, the average organic matter was41.28g/kg; The average total nitrogen of5-year greenhouse farming layer was3.87g/kg, the average total phosphorus of4.8g/kg,the average organic matter of53.05g/kg; The average total nitrogen of8-year greenhouse farming layer was2.76g/kg, the total average phosphorus of3.31g/kg, the average organic matter of46.27g/kg; The average total nitrogen of natural farmland layer was1.94g/kg, the average total phosphorus of3.39g/kg, the average organic matter of30.09g/kg. With the increase of depth, the various indexes of the Soils from GF and NF content decreased, greenhouses farmland nitrogen and phosphorus in the soil indexes were significantly higher than the natural farmland except for total phosphorus.(2) The average underground water total nitrogen of4-year greenhoused farming layer was412.38mg/L, total phosphorus was5.28mg/L, nitrate nitrogen was132.38mg/L, ammonia nitrogen was25.11mg/L; The average underground water total nitrogen of5-year greenhoused farming layer was301.49mg/L, total phosphorus was 7.77mg/L, nitrate nitrogen was114.94mg/L, ammonia nitrogen was47.11mg/L; The average underground water total nitrogen of8-year greenhoused farming layer was284.88mg/L, total phosphorus was7.3mg/L, nitrate nitrogen was72.24mg/L, ammonia nitrogen was5.53mg/L; The average underground water total nitrogen of natural farmland farming layer was74.98mg/L, total phosphorus was22.63mg/L, nitrate nitrogen is2.76mg/L, ammonia nitrogen was4.12mg/L. With increasing depth, the each index content of underground water gradually decreased. Greenhouse farmland nitrogen and phosphorus level from underground water were significantly higher than the open farmland except for total phosphorus.(3) The total nitrogen of crops from GF and NF was aboveground parts> underground parts;5-year of greenhouse>4-year of greenhouse>8-year of greenh-ouse>natural farmland.The total phosphorust of crops from GF and NF was und-erground parts>aboveground parts;8-year of greenhouse>5-year of greehouse>4-year of greenhouse> natural farmland.(4) The average nitrification rate of soils from GF and NF was8-year of greenhouse>5-year of greenhouse>4-year of greenhouse>natural farmland.The average soil denitrification rate of the Soils from GF and NF was natural farmland>5-year of greenhouse>4-year of greenhouse>8-year of greenhouse. The average soil respiration rate of the Soils from GF and NF was4-year of greenhouse>5-year of greenhouse>8-year of green-house> natural farmland.(5) The output of nitrogen and phosphorus in the Soils from GF and NF showed that with the greenhouse farmland Tilled longer, the loss of nitrogen and phosphorus increased, gaseous nitrogen oxides nitrogen loss amount was gradually increased, gaseous nitrogen losses was main way of nitrogen loss from farmland.(6) The two-factor variance analysis showed that planting pattern and depth were significantly affected the transport characteristics of nitrogen and phosphorus. The regression analysis showed that the main influence factors of nitrogen and phosphorus losses from underground water was agricultural measures (fertilizer amount, watering amount), farmland basic properties (temperature, humidity, size, cropping patterns) and soil characteristics of nitrogen and phosphorus (total nitrogen, nitrate nitrogen), the basic properties of which the greatest impact on farmlandnitrogen and phosphorus losses. In the existing GF and NF, the output of nitrogen and phosphorus has a directrelationship with fertilization. Optimization of water and fertilizer management,scientific fertilization, reasonable irrigation could effectively reduce nitrogen andphosphorus loss; cultivated land in time and necessary land consolidation on thetillage layer to make the soil in reasonable state of ventilation, which could effectivelyreduce the gaseous nitrogen losses; The reasonable variety of crops rotation couldreduce the loss of nitrogen and phosphorus,with greenhouses tilled time longer,thesoil field capacity significantly reduced, the risk of nitrogen and phosphorus lossincreased, it should be dismantled life long greenhouses, return natural farmland.