| There are so many and large rains in May to August every year of Jianghan Plain region. Since the low-lying land, excessive reclaiming land from lakes, lakes swamps and irrigation ditches aging and other reasons, causing the water table of farmland to raise and rainwater retention, the formation of low-yield farmland waterlogged, and ultimately formated the low-yield fields. Rice is the main food crop of Jianghan Plain region, due to the long-term affected by waterlogged stress, resulting in reduced rice production and low economic benefits, and severely restrict the sustainable development of agriculture in the region. How to optimize cropping patterns and land use patterns to achieve maximize use of resources and the sustainable devolopment of ecological environment while protecting the crop yields and farmers’incomes is great significance for the sustainable development of agriculture in the region. To solve the question, this study is of full utilization of waterlogged farmland resources, put Jianghan Plain three common waterlogged farmlands as research objects:surface waterlogging conditions, general waterlogging farmland and severe waterlogging farmland. According to the local climatic conditions (temperature, light, heat) and endemic water features. We Set up the watermelon-corn interplanting pattern under the surface waterlogging conditions, paddy field shrimp culture pattern under the general waterlogging conditions and coix monoculture pattern under the severe waterlogging conditions,was compared with the tradition rice monoculture pattern under the same waterlogging conditions, respectively, by a two years field study experimental and chemical experimental in room.To analyze the impact of various modes of farmland for soil major greenhouse gases (CO2, CH4) emissions, paddy water quality and soil chemical properties. The main contents and results are as follows:(1) A field experiment from 2013 to 2014 showed that. NH4+-N, NO3--N, TN, orthophosphate salt and TP concentrations in paddy water of the different cropping patterns were higher at early crop growth and decreased at the late crop growth, under Waterlogging Farmland. Thisshould be promptly applied fertilizer. In general waterlogging,2013,NH+4-N, NO3--N, TN in shrimp cultured pattern paddy field were higher 1.21 times,1.36 times and 1.05times than CK2,and concentrations of H3PO4-P and TP are Less than CK2.2014 RS processing water NO3--N. TN, H3PO4-P and TP were higher 1.22 times 1.04 times,1.03 times,1.62 times than CK2, respectively, and the concentrations of NH4+-N less than CK2. Shows that paddy field shrimp culture pattern would increased concent of N, P of paddy water body. Severe waterlogging rice fields,2013, NH+4-N, TN, H3PO4-P and TP of coix monoculture pattern paddy water were less 0.87 times, 0.96 times, 0.9 times and 0.95 times than CK3.respectively. While the N0-3-N increased is 1.06 times than CK3.2014, NH4+-N, NO3--N, TN of coix monoculture pattern paddy water were increased 1.13、1.21 ' 1.05 times than CK3 respectively,and concentrations of H3PO4-P and TP of coix monoculture pattern paddy water were less than CK3.(2) Effects of different planting patterns on pH, NH4+-N and NO3--N of soil observation results showed that paddy soil pH of different cropping patterns is stable relatively, and fluctuating range between 6.80-8.27 in crop growth period, and were not significantly different. NH+4-N and NO3-N of each mode paddy soil under three waterlogged showed significant seasonal variation in crop growth cycle. There show higher content of nitrogen in the soil in early crop growth, and gradually reduced in the late crop growth, NH4+-N and NO3-N content of soil varied from 0.72～23.47 mg/kg and 0.74～8.34mg/kg. Soil N in shrimp cultured pattern paddy field and coix monoculture pattern paddy in two years change are not consistent. Watermelon-corn interplanting pattern can improve soil nitrogen nutrition, and in 2014 reached a significant level in NH+4-N content of watermelonlcorn model soil in 2013 and 2014were 3.03 mg/kg and 5.20 mg/kg, respectively, are 1.04 and 4.9 (p <0.05) times compara to CK1,and the NO3--N c contents were 19.20 mg/kg and 4.05 mg/kg, respectively, were 1.02 and 1.15 times compara to CK1.(3) Effect of different planting patterns on CO2 and CH4 emissions of waterlogged paddy through field in-situ experience and the results showed that CH4 emissions from each mode land were focused on transplanting to jointing stage, and accounted for 49.43%～80.96% and 52.94%-98.20% of full gowth period respectively in 2013 and 2014. Compared to controls under the same conditions Waterlogged in 2013, WM can reduce the total CH4 emission under the surface waterlogged rice fields and reduced 77.16% (P<0.05), General waterlogging paddy RS can reduce the total CH4 emission compared with the control, energy efficient treatment to reduce the total CH4 emissions and reduce 64.73% (P<0.05), severe waterlogging paddy CL treatment also significantly lower than the control, a decline of 43.13% (P<0.05). average emissions and total emissions of CH4 have decreased in 2014, but no significant difference compared with the control.CO2 emissions peak of different crops appeared at rice tillering critical period to heading period in the rice season, CO2 emissions accounted for 22.01%～37.48% and 15.6-65.75% of total emissions respectively, of different modes in rice season of the in 2013 and 2014, WM, RS, CL treatment decreased the amount of soil CO2 emissions in 2013 and 2014, the total CO2 emissions of the WM were lower than CK1 and decline of 54.6% (P <0.05)in 2013, CO2 emissions of RS were lower 20.84% than CK2,CO2 emissions of CL are lower 58.96% (P <0.05) than the CK3 in 2013, 2014 except RS treatment significantly reduced the CO2 emissions of paddy, decline of 58.96%(P <0.05). Although the total amount of CO2 emission of WM and CL lower than the CK1 and CK3, respectively, the difference was not significant.(4) Estimation of comprehensive warming potential (GWP) of CH4 and CO2 of different planting patterns showed that, comprehensive global warming potentials of CH4 and CO2of WM under general waterlogged paddy were 15552.8 CO2kg·hm-2 and 12846.45 CO2kg·hm-2 was reduced by 54.6%(P <0.05) and increased by 62.0% (P<0.05)than control in 2013 and 2014. comprehensive global warming potentials of CH4 and CO2 of RS were 37978.84 CO2kg·hm"2 and 11928.53 CO2kg·hm-2 was reduced by 22.0% and 15.0%(P<0.05) respectly under general waterlogging paddy soil than CK2. Comprehensive global warming potentials of CH4 and CO2 of CL were 14896.83CO2kg·hm-2 and 13023.21CO2kg·hm-2 and was reduced by 58.7%(P<0.05) and 14.0% than CK3.(5) The economic benefits of the new patterns of surface waterlogged paddy, generally waterlogging paddy and waterlogging paddy are higher than the traditional patterns, which can effectively improve crop yields of waterlogging farmland and farmers’ incomes in the two-year field experiment. The total investment and net revenue of WM in surface waterlogging paddy in 2013 are 20176.5 CNY.hm-2 and 30146.5 CNY.hm-2, respectively, are 1.6 and 4.2 times compared with CK1. Furthermore, in 2014, the total investment and net income are 20106.9 CNY.hm-2 and 35592.5 CNY.hm-2, respectively, are 1.6 and 3 times compared with CK1. The total cost and net income of RS in general waterlogging farmland in 2013 is 28805.5 CNY.hm-2 and 18310.5 CNY.hm-2, respectively equivalent 2.3 and 2.8 times to CK2, Simultaneously the total investment and net income in 2014 are 23679.8 CNY.hm-2 and 12567.8 CNY.hm-2.and equivalent 1.9 and 3.1 times to CK2. The total expense and net income of CL in severe waterlogging field in 2013 are 14037.5 CNY.hm-2 and 9962.5 CNY.hm-2, are 1.1 and 2.6 times to CK3, In 2014, the spending and earning. |
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