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SCI论文目录 |
稻草还田对水稻氮、钾营养特性的影响及其产量效应研究 |
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| 出 版 社：中科院硕士学位论文 |
| 发表时间：2006.07 |
| 台 站：
桃源农业生态试验站
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| 作 者：佘冬立 |
| 点 击 率：4763 |
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| 关 键 字：稻草还田；施氮模式；土壤供氮量；N、K吸收量；产量 |
| 摘 要：研究稻草还田及其与氮肥配施对稻田土壤肥力及稻谷产量的影响,是合理利用农业废弃物、制定合理施肥模式的前提。本文通过稻草还田长期定位试验和桃江3年、桃源2年稻草还田专题试验，研究了稻草还田土壤肥力的长期和短期效应，重点探讨了土壤供氮特性和水稻氮、钾吸收特性，以及对作物生长、产量的影响。结合氮肥管理模式（不同施氮量和不同施氮时期）下稻草还田短期综合效应的比较研究，探索了稻草还田后适宜的氮肥管理措施。主要结果如下：
⑴长期稻草直接还田显著提高了土壤有机质、全氮的含量。稻草还田对土壤NH4+-N浓度的影响与季节有关，且不受施N水平的影响。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含量的提高具有促进作用；而当年早稻收割后新鲜稻草直接翻压还田，稻草C/N较高，稻草分解使晚稻土壤NH4+-N含量略低于移走稻草处理，因此新鲜稻草秋季还田效果较好。稻草还田配施N肥显著增加了土壤可矿化N含量，促进水稻对N素的吸收，从而达到增产目的。土壤可矿化N与植株吸N量具有显著的正相关关系（r2=0.506*）,与作物产量也具有显著的正相关关系（r2=0.590*）。
⑵ 长期定位试验结果表明，养分当量相同的“化肥+稻草还田”和“纯化肥”试验两处理的稻谷产量差异不显著，但化肥+稻草还田处理相对于纯化肥处理利用稻草养分循环再利用替代了16 % N、24 % P和64 % K的化肥投入，说明稻草还田可替代相等当量化肥施用。
⑶ 不论在背景氮较低的砂性土壤上还是在背景氮较高的粘性土壤上，稻草还田配施减量氮肥(N1、N3：全年施氮量180 kg/hm2)处理，相对于移走稻草+高量氮肥(N2：全年施氮量240～265 kg/hm2)处理之间稻田系统生产力无显著差异，但每年节约60～80 kg/hm2纯氮化肥的投入，提高了其边际成本报酬率。分次施氮的效果表明，稻草还田下等量氮肥不同施氮模式（N1、N3）处理之间，水稻产量差异不显著，但水稻吸氮高峰集中在分蘖期至孕穗期，N1模式减少了基肥施氮量，防止了因作物未能及时吸收导致的土壤速效氮的损失，而适当增加作物后期施氮量又能有效缓减作物后期生长大量吸氮的要求与微生物分解稻草固持矿质氮之间的矛盾，改善了土壤的供氮状况，其效果最优。因此，在全年稻草还田量为7500 kg/hm2的红壤稻田系统，根据投入氮肥的边际收益，全年适宜配施氮量为180 kg/hm2，且各时期施氮量优化比例为基肥30%，分蘖肥30%，穗肥40%。
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| 关 键 字(英文)：Incorporation of rice straw; Nitrogen application model; Soil N supply; uptaking of N、K; Rice yield |
| 摘 要(英文)：Researches on the effects of rice straw incorporation and N fertilizer application are useful for understanding changes in soil fertility and grain yield, and also helpful for making reasonably utilizing of organic matter and fertilization strategies. In this paper, a long-term rice straw incorporation experiment and a three-years’ field experiment at Taojiang and a two-year’s field experiment at Taoyuan Station of South China were conducted to examine soil fertility effects of rice straw incorporation in long and short term, especially their effects on soil N supply, uptaking of N、K by plants and rice growth and yield. Through comparing short-term effects of rice straw incorporation under different nitrogen management (N rates and ratio N application), the suitable N fertilizer management for field with straw incorporation was obtained. The main results were as follows:
⑴ Soil organic matter and soil total nitrogen had a significant increase with a long-term rice straw incorporation. The impacts of rice straw incorporation on soil NH4+-N were different in different season, and there was no significant relationship with N rates. At the early rice season, rice straw incorporated at last autumn increased the soil NH4+-N, while the effect was negative at the latter rice season with the fresh rice straw incorporated immediately after early rice maturing. The soil mineralisable N was significantly increased with rice straw incorporation matching N fertilizer, so to improve the nitrogen absorption by the crops and the productivity. Soil mineralisable N had a significant positive relationship with the nitrogen absorption by the crops（r2=0.506*）and rice productivity（r2=0.590*）respectively.
⑵ The grain yield of fertilizer+rice straw was 80 % higher than that of CK, but there
wasn’t significant difference between the yield of fertilizer +rice straw and fertilizer treatment in the long-term experiment. The fertilizer +rice straw treatment using organic fertilizer substituted for 16 % N、24 % P and 64 % K in contrast to “fertilizer” treatment. So we can conclude that rice straw incorporation could substitute fertilizer partly in the paddy system, especially K.
⑶ Either in the sand soil with low indigenous N supply or in the clay soil with high indigenous N supply, there was no significant differences of rice productivity between the treatment of straw incorporation + recommended lower level N (N1, N3: 180 kg/hm2 per year) and the treatment of straw removed + higher level N (N2:240～265 kg/hm2 per year), but the former saved 60～80 kg fertilizer N per year, so improved the marginal benefit-cost ratio of N fertilizer. Even through there were no significant differences of rice productivity between straw incorporation + N1 and straw incorporation + N3, with the same fertilizer N level but different application models, the model of N1 decreased the amount of base N fertilizer used, but increased the tillering and booting N fertilizer used, and its effect was best. The period of tillering stage to booting stage was an important time for rice nitrogen uptake. The lower base N fertilizer could avoid from the loss of soil available nitrogen resulted from the lower N uptake by plants. The contradiction between the large quantities of N need by plants and the immobilization of soil available nitrogen by microbial decomposing fresh rice straw could be solved by the increased topdressing N fertilizer at tillering and booting stages. So, in the red earth-paddy system with 7500 kg/hm2 rice straw incorporation per year, the suitable amount of N fertilizer used was 180 kg/hm2 per year, and the proportion of N fertilizer used was base N fertilizer 30%, tillering N fertilizer 30%, booting N fertilizer 40%.
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