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SCI论文目录 |
稻草覆盖还田的氮、钾肥优化管理和生态效应研究 |
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| 出 版 社：中科院硕士学位论文 |
| 发表时间：2007.07 |
| 台 站：
桃源农业生态试验站
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| 作 者：尹春梅 |
| 点 击 率：5568 |
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| 关 键 字：稻草还田；肥料管理优化；产量；冬闲期；土壤温、湿度；杂草；CO2通量 |
| 摘 要：从生态建设和环境变化的角度出发，加强亚热带红壤区有机无机养分配施研究，了解土壤肥力和系统生产力的变化趋势，明确提高稻草还田的土壤肥力、产量和生态环境效益，对农业健康和可持续发展都有重要的意义。本文通过“稻草还田与氮肥的管理模式优化”和“稻草还田与钾肥的管理模式优化”两个田间试验，比较了不同氮钾施用模式下稻草还田的肥力与产量效应，探索基于稻草还田的氮、钾肥优化管理模式；通过“冬闲稻草覆盖还田效应”试验了解长达5个月的红壤稻田冬闲期CO2通量动态，研究晚稻收割后，稻草覆盖还田的生态效应及其对CO2通量的影响。主要结果如下：
（1）稻草直接还田对早晚稻各处理有不同的影响。头年晚稻草秋季还田经过冬季的分解，稻草C/N降低，对来年早稻土壤NH4+-N含量的提高有促进作用；而当年早稻收割后新鲜稻草直接铡断还田，稻草C/N较高，对土壤NH4+-N的效应因不同的施氮模式而有所差异。长期稻草直接还田显著提高了水稻产量，在本试验中水稻产量N1>N2>N3>N0,三个施氮处理与不施氮处理产量差异显著，试验的最优组合为稻草还田加上施氮量（180kg•a-1），其中40％穗肥于移栽后30天施用，即（N1＋A）处理。
（2）稻草还田可以显著提高水稻各生育期土壤速效钾含量。但在土壤钾素背景含量较高，不构成产量增长的限制因子时，钾肥的高投入，无论是以化肥的形式还是有机肥的形式都难以产生相应的产量增长。在本试验的生产力水平下，亦即水稻产量水平在10,000 kg•hm-2•a-1左右的时候，钾肥施用量为60 kg•hm-2•a-1＋稻草还田7,500 kg•hm-2•a-1处理是最佳的钾素投入水平（K3＋S）。
（3）亚热带稻作区休闲期CO2通量主要受气温影响，二者呈极显著的正相关。稻田休闲期CO2排放通量有明显的日变化规律，表现为昼吸夜排。太阳辐射和温度是影响稻田休闲期生态系统CO2通量日变化的重要环境因子。稻田休闲期生态系统CO2通量日变化和季节变化均与近地面大气中CO2浓度呈极显著直线相关，但随气温的升高，这种相关性呈减弱趋势。
（4）稻草覆盖还田对冬闲稻田的生态效应主要包括四个方面：保温、保水、抑制田间杂草生长以及增加了指向大气的CO2排放。覆盖对土温的影响主要在地下5cm层，试验期内，温度较无覆盖日均高出1.0～3.2℃；覆盖对耕层水分的影响主要在0～15cm层，覆盖与无覆盖之间差异达到极显著水平；另外覆盖显著改变了冬闲稻田生态系统的CO2通量变化情况，试验期内，由无覆盖的平均净吸收1.99gCO2•m-2•d-1转为覆盖处理的平均净排放2.68gCO2•m-2•d-1。使冬闲稻田由大气的碳汇变为碳源。
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| 关 键 字(英文)： Straw mulch; Fertilizer manage model; Rice yield; Wintry fallow paddy; soil temperature and moisture; weed; CO2 fluxes |
| 摘 要(英文)：As a main type of ecosystem, subtropical red paddy region represents an important economic and ecological resource at mid-china. This paper is write to discussed fertilizer(N&K)、yield and ecology effect of rice straw mulch on red soil paddy field by the field experiments. The main results were as follows:
(1) There are different effects of the mulching time between early rice and later rice. Rice straw mulching after the harvest of later rice, the straw could be decomposed during the winter, the ratio of C/N would decrease, there were improving effects to soil NH4+-N of each treatment in next early rice season; but the effects of mulching after the harvest of early rice were different by different N application. According to the experiment, rice straw mulch improved rice yield significantly. The rice yield order is N1>N2>N3>N0, the yield of three treatments applied N was significantly more than no N application. The best N application mode in this experiment is: with rice straw mulch 7500kg•hm-2•a-1 and 180 kg•hm-2•a-1 N application. And the proportion of N fertilizer used was base N 30%, tiller N 30% and 40% as booting N. Scilicet, The best is treatment（N1＋A）.
(2) Rice straw mulch can increase soil quick result K during the growth of rice. But in high K background situation, K is not the restrict fact of rice yield. High devotion of K fertilizer neither by using chemical fertilizer nor rice straw can lead to relevant increasing of rice yield. Through this experiment, when rice yield is around 10000 kg•hm-2•a-1, 60 kg•hm-2•a-1 chemical K + rice straw mulch 7,500 kg•hm-2•a-1 is the most suitable K application mode（K3＋S）.
(3) Measurement data of CO2 fluxes during winter shows that CO2 concentration near the ground and CO2 fluxes were changing in the same pace, and the seasonal dynamics of CO2 fluxes appeared marked linear relationships with air temperature. The daily dynamics of CO2 fluxes of non-cropping wintry paddy field in subtropical region is: during the daytime, affected by Photosynthesis Available Radiation (PAR), paddy ecosystem fixed CO2 from atmosphere, there was a very conspicuously logarithmic relationship between PAR and CO2 fluxes; during the night, respiration progress of weed and soil emitted CO2 into atmosphere, and temperature was the main influence factor. It proved that air temperature (Ta) and soil temperature under 5cm (Tg5) were the most suitable index for describing the linear relationship between CO2 fluxes and temperature. During the fallow period (154d), the paddy ecosystem fixed 4.13 tCO2•hm－2 from atmosphere。
(4) Effect of Straw mulch on wintry paddy includes increasing the soil temperature, retarding the loss of surface soil moisture, checking the weed growth, and strongly influencing the CO2 fluxes between agro-ecosystems and atmosphere. Straw mulch impacts on CO2 fluxes mainly through two aspects: The one is altering the soil temperature, which in turn affects microbial growth and decomposition processes that transform plant-produce C to soil organic matter (SOM) or CO2; the other is restraining the growth of the weeds in the field, which in turn decreases the photosynthesis process of the agro-ecosystem. Though straw mulch also has effects on Water Content in soil surface layer, which is considered to be an important factors to CO2 fluxes too, there is no significant influences been tested in this experiment.
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