| Tillage and fertilization have a great impact on nitrogen use in paddy field. The cultivation way affected the soil spatial structure and the sludge fertilizer condition, has created the different soil environment for the crops growth, changed the nitrogen migration conversion process in the soil, then had the different influence on the crop output and the fertilizer use. This research selected the rape-rice croping field of Hubei Province Wuxue city for the object of study, through big field experiment to study the fertilizer losses and use efficiency.under different tillage and nitrogen fertilization. The experiment mainly has studied under different tillage practices the way loss processes and the influencing factor of the N in the N2O release, the ammonia volatility, NO3-infiltration and so on, discussed soil and the microorganism to the N fixed rule, cleared in the rice paddy soil the N transformation and the whereabouts, simultaneously analyzeed these losses to the nitrogenous fertilizer use factor influence. Is for the purpose of discovering that this area exempts plows the rice paddy the nitrogen loss process and the transformed characteristic, then for highly effective fat and reduces N using N the environment harm to provide the scientific basis. The experimental main conclusion includes:1.The study of tillage and fertilization on nitrogen transformation of paddy field1) Tillage and fertilization enriched nitrogen in the soil surface. Fertilization significantly increased soil NH4+ content at 0 to 10 cm levels.and soil NO3- content at 0 to 5 cm levels. No-tillage significantly increased 0 to 5 cm layer soil NH4+ content and soil NO3- content at 5 to 10 cm levels.2) Fixed ammonium content of soil was obvious stratification,10 to 20 cm soil layer were significantly less than 0 to 5 cm and 5 to 10 cm soil layer. Fertilization significantly increased the fixed ammonium content at 0 to 5 cm levels, and add a new fixed ammonium content. No-tillage fertilization showed strong ammonium fixation capacity and the ability to release ammonium.3) The soil microbial biomass N decreased with the layer increasing. Fertilization slightly increased the amount of soil microbial N content all layer. No-tillage fertilization of microbial biomass N content in the 0 to 10 cm levels were higher than tillage fertilization, in the 10 to 20 cm layer lower compared with tillage fertilization.4) The enzyme activity of the soil increased with soil increases. Fertilization can significantly improve the soil urease activity,the protease activity at 0 to 10 cm levels and the dehydrogenase activity at 0 to 5 cm levels. No-tillage treatment significantly increased soil urease, protease and dehydrogenase activity at 0 to 5 cm levels.2.The study of tillage and fertilization on nitrogen loss of paddy field1) Fertilization can significantly increase three nitrogen concent in leakage water in paddy field. Tillage fertilization of three nitrogen concentrations and total nitrogen leakage were significantly lower than no-tillage fertilization. Nitrogen leakage occurred in the peak within 2d after fertilization. The leakage of each treatment reached the maximum after the base fertilizer employment,occupied the total leakage of 45% to 46%.2) Fertilization significantly increased N2O emission. N2O emission flux and the total release of no-tillage treatment was significantly higher than tillage. N2O emission flux in all treatments at 1 week after application of nitrogen fertilizer achieved maximum value and then decreased rapidly. N2O emission was biggest at 1 week after base fertilizer application,occupied 12% to 14% of the total emissions.3) Fertilization significantly increased emission flux. NH3 emission flux and the total release of no-tillage treatment was significantly higher than tillage. After applying fertilizer, ammonia volatilization of all treatment achieved the peak value immediately, reduced rapidly afterward. The maximum ammonia volatilization occured in the base fertilizer period, and NH3 volatilization loss reached the largest of the total amount of ammonia volatilization of 10% to 13% at the 1 week after base fertilizer employed.4) The NH3 volatilization loss occupied the total N losses 64.7% to 72.9%, Fertilization treatment significantly increased the total N loss, no-tillage treatments of the total N loss and maximum loss rate of N fertilizer are higher than tillage treatments.3.The study of nitrogen use efficiency under different tillage1) Fertilization was conducive to the growth of rice, fertilization of the rice yield and rice N uptake were higher than non-fertilization, respectively increased by 33.7% to 34% and 46.9% to 53.7%. But fertilization also reduced nitrogen harvest index, was conducive to luxury consumption of nitrogen in rice plants. NO-tillage fertilization of rice N uptake and yield were slightly lower than the tillage fertilization, and the dependency rate also slightly lower than the tillage fertilization, which indicated that rice less dependent on soil nitrogen under no-tillage.2) Nitrogen absorption efficiency of no-tillage same to tillage, respectively were 15.75%.and 14.50%. The nitrogen physiological efficiency,the nitrogen agronomic efficiency and the nitrogen partial factor productivity of no-tillage fertilization were less than tillage fertilization by 12.63 kg·kg-1,0.18 kg·kg-1 and 1.17 kg·kg-1. That means no-tillage fertilization is not conducive to efficiency. Key word:Rice; No-tillage; Nitrogen; Nitrogen transformation; Nitrogen loss; Nitrogen use efficiency... |
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