The Evaluation Of Nitrogen Management On Comprehensive Effect Of Nitrogen Fertilizer In Maize Field

In order to keep the corn yield as well as to fertile the soil and to reduce agricultural non-point source pollution from unreasonable fertilization, monitoring was carried in Linghai on soil, soil leaching solution, plant, greenhouse gas emission with practical nitrogen application modes by the methods of the in-situ soil solution collection and indoor soil column leaching simulation and manual static opaque chamber/gas chromatography and chemiluminescence measuring systems from2009to2011.At last, Integrated Evaluation Indexes of different nitrogen application treatments were calculated with quantitative evaluztion method.The results are as follows:1. Under the condition of natural rainfall in Linghai area, different nitrogen application modes couldn’t lead to the nitrogen leaching in the short term. Under the condition of soil column leaching simulation, leaching of soil available nitrogen increased with fertilizer rate. Leaching process of nitrate nitrogen from source of soil was relatively slow, while leaching of NO3-N from fertilizer was concentrated in the3～8times, accounting for86.7%of the total leaching rate. Nitrate nitrogen was the main form of nitrogen leaching. Straw returned treatment (OPTS) treatment lowered the water contents of soil in0-120cm layer.2. Nitrogen application disturbed the distribution of nitrogen in soil layers. Variation of available nitrogen in the shallow soil was greater than that of the underlying soil. NO3-N&NH4-N contents of soil increased with the rate of N application. Rotten process of straw consumed some nitrogen in earlier growing season, but later soil could buffer and recover itself. OPTS treatment could keep NO3-N from migrating to the underground and lowered the risk of polluting the groundwater. Released peak of control release fertilizer (CRF) lasted for30days and its NH4-N accumulation in soil increased by17.5%compared with farmers’ conventional N fertilizer treatment (FP).Apart from the soil pH, total&available NPK and soil organic matter content was lower than original contents.CRF could increase soil organic matter, total&available N contents. Straw could effectively increase the total&available K contents. Soil nutrient indexes of CRF was83.5. Effect of CRF on soil fertilization was better than that of OPTS.3. Chlorophyll contents of CRF and OPTS were higher in later growing season, good for photosynthesis to provide more nutrient to the grain. Along with the growth, water contents of stem, leaf and panicle decreased. Dry matter content of seed from CRF was highest. N contents of the whole plant increased with N application. Yield significant between treatments enhanced with years of the experiment. Average yields of3years of CRF and OPTS increased by3.3%and2.77%compared with FP; Annual N agronomic utilization efficiency and N harvest index and grain N accumulation of CRF were higher than those of OPTS, while the plant total N accumulation and fertilizer utilization rate of OPTS were higher.4. N2O emission flux was affected mainly by nutrients in the soil. The correlation coefficient between fertilizer rate and total N2O emissions was0.986. Total N2O emissions of CRF and OPTS were increased. During earlier stage of growing season N2O emission flux of CRF was influenced by fertilizer, while more affected by the soil temperature later. With the increase of planting years, seasonal N2O emissions coefficient less affected by yield than by fertilizer rate. Therefore the effect of different N application modes on seasonal N2O emission should be researched by monitoring year by year, and should consider the N2O emissions from plant.5. Apparent residual rate of CRF was1.4times higher than that of OPT treatment, and1.3times higher than that of OPTS treatment, while apparent loss rate was1/3of OPTS; Evaluation on different N application treatments with the method of Integrated Evaluation Index indicated that IEI value of CRF treatment and OPTS treatment were37%and30.1%higher than that of OPT treatment,33.2%and27.5%higher than that of FP treatment. The method of Integrated Evaluation Index, which considered about yield and environment and soil fertility promotion and resources utilizing was used to evaluate the result of the experiment, while the method and its evaluation indexes need to be perfected.Considering soil fertilizing and yield and as well as N absorb of plant and GHG emission reduction, control release fertilizer application was recommended.