Study On The Paddy Nitrogen Balance Under Different N And Water Coupling In Typical Red Soil Areas

By using field water balance devices, we designed two kinds of rice irrigation (intermittent irrigation and flooding irrigation); Not fertilizer (as CK), applied 140 kg/hm~2 nitrogen (two kinds of application forms: N-2nd and 3rd income) and applied 210 kg/hm~2 nitrogen (three kinds of application methods: N-2nd, 3rd and 4th income). There were 12 different combinations of water and nitrogen. This paper studied the nitrogen balance features under different N and water coupling in typical red soil areas of our country, both main input and output of nitrogen balance have been analyzed in double-crop rice paddy ecosystem of this areas, which including dry and wet nitrogen deposition, fertilizer N, irrigation, and nitrogen capacity absorbed by crop, ammonia volatilization, runoff and leakage, respectively, and studied the input and output of items on the contribution of nitrogen balance, clarified the different coupling of water and fertilizer on rice production and nitrogen utilization.Nitrogen balance features during the early and late rice: In April 26, 2005 to July 13, 2005 at the rice growing period, the input by fertilization, irrigation and atmospheric deposition to the red soil of farmland ecosystems were imported 32.2 - 244.8 kg/hm~2. Through ammonia volatilization, runoff, spills and a total output of crops absorb 100.0-229.7 kg N /hm~2. N fertilization of a surplus of 2.9 - 44.5 kg/hm~2. In July 17, 2005 to October 9, 2005 at the late rice growing period, red soil ecosystems through fertilizers irrigation and the importation of atmospheric deposition of nitrogen 30.4-241.2 kg/hm~2. Through ammonia volatilization, runoff, leakage and crops absorb 61.3 - 194.6 kg N /hm~2. Nitrogen fertilization of a surplus of 41.2 - 61.7 kg/hm~2. Atmospheric nitrogen deposition has become one of the main input items in red soil areas of farmland nitrogen balance. During early and late rice, atmospheric dry deposition of nitrogen in the volume, there was no difference, but during early rice , the wet atmospheric nitrogen deposition was greater than late rice.The effects on early and late rice yield, yield's components and N use efficiency under different irrigation patterns, different N application and different N regulation in red soil areas were studied. Results showed that, compared with flooding irrigation,intermittent irrigation had more yield and total N uptake than flooding irrigation, but apparent N recovery efficiency was lowe; with the rise of nitrogen application, yield, total N uptake and nitrogen use efficiency increased; split applications significantly increased yield, total N uptake and apparent N recovery efficiency, but these were not significant difference between treatments of three and four time N application. The water and fertilizer management measure, which was adopted the introduction of intermittent irrigation, fertilizer capacity of 210 kg/hm~2, nitrogen application form for basal 50% + tiller fertilizer 30% + jointing fertilizer 20% , is more reasonable. Local peasants often used the water and fertilizer management measure which adopts the introduction of flooding irrigation, fertilizer capacity of 140 kg/hm~2, nitrogen application form for basal 50% + tiller fertilizer 30% + jointing fertilizer 20% and fertilizer management measures. Compared with the measure which local peasants often used, the early rice can raise 631 kg/hm~2, nitrogen utilization to 36.7%; Rice output 944 kg/hm~2, N utilization to 47.5%.