Effect Of Different Irrigation And Nitrogen Conditions On Nitrogen Leaching And Nitrous Oxide Emissions In Paddy Soil

As an agricultural country, the science inquiry is particularly important for agriculture in China. As one of the main food crop, study on the problems about the various aspects in rice production has become hot topic in today’s agricultural scientific research frontiers. Water and nitrogen are two important limiting factors in the process of rice growth. At present, the serious lack of water resources in agricultural sustainable development has been on major issues in China; Nitrogen is one of the important nutrients directly affect the yield of rice, then resulting in the phenomenon of unreasonable usage of fertilizer in rice production, and produce many incidental problem, such as soil ecological environment destruction, non-point source pollution and increased greenhouse gas emissions. So, the comprehensive study on rice water saving irrigation and nitrogen nutrition of reasonable application in paddy soil will became the important direction and the field of scientific research in the future. This study is of great significance not only to the rice production, but also to the improvement of the ecological environment of rice has important research value.This research adopts the experimental design 2×4 double factors fully interactive, divided into different irrigation measures (CI:control irrigation; CF:conventional irrigation) and different nitrogen levels (N0:300 kg · hm-2; N1:reducing nitrogen 10%; N2:reducing nitrogen 20%; N3:nitrogen 40%reduction), through the zetetic experiments in the field of the continuous two years, to study the control effect of water-saving irrigation measures, different conditions of water and nitrogen on rice yield and ecological environment of paddy fields, nitrogen leaching the leakage and the influence of nitrous oxide emissions. The experimental results showed that two years:1) under different water and nitrogen conditions of effective ear Numbers per spike and the influence of rice reached significant level, the experimental results show that the water-saving irrigation control and the increase of nitrogen fertilizer can obviously increase the effective panicle number and grain of rice, the nitrogen level difference influence on the rice yield difference is obvious, and the influence of different water conditions on rice yield effect is not significant.2) under different water and nitrogen conditions, physical and chemical properties of paddy soil also received a significant effect, the experimental results show that the pH of the rice with the loss of the n application rate. In conventional irrigation treatment, n application rate reduced to 20% of the conventional n application ammonium nitrogen and nitrate content reduced reached significant level, and water-saving irrigation control processing of ammonium nitrogen in n application rate reduced to 20%of the conventional n application levels significantly lower, nitrate content only in n application rate reduced to 40% of the conventional n application at reduction did not reach significant level. Under the condition of same n application levels, soil pH value displayed as normal irrigation treatment is slightly higher than that of water saving irrigation control, but in the period between the change did not reach significant level; Soil total nitrogen content of conventional nitrogen and nitrogen 40% reduction in the two treatment significantly higher than the conventional irrigation water-saving irrigation control content, content of nitrate nitrogen content only in n application rate reduced to 20% of the conventional n application, water-saving irrigation control the content of treatment significantly higher than the conventional irrigation, other did not reach significant difference were observed in the processing level.3) Because of soil nematodes were often as sensitive biological indicator of different farmland management measures, so I chose to work with the influence of different water and nitrogen conditions on soil nematode community to indicate changes in paddy ecological environment situation, the experimental results show that the observed eight processing of the communist party of China 16 28 genera of soil nematodes,7 families,12 genera respectively for food bacteria nematodes, fungi, nematodes 3 4 genera, predatory nematodes 3 families,5 genera, omnivorous/3 to 7 genera of predatory nematodes. The wire tail pad blade is Filenchus for all processing advantages,35.4%-47.9%of the total number of all nematodes. In all treatments, fungivores accounted for the highest, feed bactervores followed, then the plant-feeders, omnivorous/predatory at least. Conventional irrigation under the condition of soil nematodes slightly larger than the total control irrigation of total nematodes, but there was no significant difference; When N application rate reduced by 20%(down to 240 kg N · hm -2), the amount of soil nematodes is an obvious increase, and with the further reduce the N application rate, total number of nematodes and no further change.4) The condition of different water and nitrogen on the depth of different soil seepage of NH4+-N, NO3 --N concentrations have different degree of influence. At 20 cm soil depth in the soil seepage, under the condition of same water, seepage of NH4+-N, NO3--N concentrations were reduced with the decrease of nitrogen. Rice paddies,80 cm soil seepage, NO3--N concentrations rise along with the increase of N application; Under the condition of the same nitrogen level, under the water saving irrigation control of NO3--N concentration was significantly higher than that of conventional irrigation, and irrigation had no significant effect of NH4+-N concentration; Improved significantly compared with the conventional irrigation, irrigation control seepage of NO3--N concentrations,31.17%; Irrigation and nitrogen levels had no significant effect on NH4+-N.5) Different conditions of water and nitrogen on rice field the influence of nitrous oxide emissions in each period of rice growing. Nitrous oxide emissions peak generally appear in every time after fertilization, and obvious dry-wet alternate field change over time, in addition to the rice yellow ripeness stage, the water-saving irrigation control treatment nitrous oxide emissions than conventional irrigation. In the rice yellow ripeness stage, N2O emissions from conventional irrigation treatment is larger than that of control irrigation treatment. Comparing of four rice growth stage, the N2O emissions at the jointing education stage is the biggest.