【作者】 张奇春；

【导师】 王光火；

【作者基本信息】 浙江大学 ， 农业资源利用， 2005， 博士

【摘要】 本文以稻田土壤氮素转化和水稻合理施用氮肥为研究目的,通过水稻长期定位肥料试验和水稻优化氮肥施用试验,采用室内培养,大田试验以及相关数学分析相结合的研究方法,探讨了土壤氮素供给-水稻养分吸收-水稻产量之间的相互关系。特别是采用先进的现代仪器分析技术和测定方法,比较系统地研究了土壤氮素转化机理及土壤供氮能力,取得了许多有意义的研究结果,为制定合理的水稻施肥方案,减少氮肥污染提供了理论依据。本文所获得的主要研究结果如下: 1、长期定位肥料试验结果表明,水稻产量与水稻吸氮总量、吸磷总量和吸钾总量极显著相关(R²分别为0.7353^**,0.5461^**和0.5599^**),其中产量与吸氮总量的相关系数最高,说明氮素营养水平直接影响水稻产量的可信度高。对土壤养分供应状况的分析表明,随着种稻季数的增加,缺肥区土壤所缺养分的土壤供应能力明显下降,从而影响对水稻生长而导致减产。与NPK处理比较,不施N肥处理（PK）从第一季起引起减产:不施P肥处理（NK）从第八季开始减产;不施K肥处理（NP）从第三季开始减产。试验田肥力水平在当地具有代表性,试验结果表明水稻重视N、P、K肥施用具有紧迫性。不同施肥处理还明显影响了水稻养分吸收利用率,水稻氮内部利用效率（IEN）范围在42～94kg kg^-1之间,磷（IEP）在128～457kg kg^-1之间,钾（IEK）在66～109kg kg^-1之间。 2、土壤微生物生态特征受多种因素的影响。本文的研究结果表明,同NPK配施处理相比较缺肥处理降低了土壤微生物量N,使微生物量C/N比增加。另外,对照（CK）微生物量N可以维持在较高水平,可见平衡施肥或土壤养分的平衡供应对于维持土壤微生物量N水平是有益的。Biolog测试表明,在32h之内,AWCD值很小,几乎没有变化。此后微生物活性增强,以NPK配施处理的AWCD值最高,CK其次,不平衡施肥处理（NP、PK、NK）相对最低。说明平衡施肥处理对维持土壤微生物活性有益。在连续种植水稻条件下,水稻对缺肥处理士壤所缺养分养分库的消耗加快,这种情况明显影响了土壤微生物量和微生物活性,对土壤氮素的转化不利。 3、有机氮是土壤氮素的主要形态,一般占土壤全氮量的95%以上。土壤供氮能力是土壤肥力的一项重要的指标。对稻田土壤的有机氮组分研究的结果表明,经过6年双季稻种植,施氮区土壤全氮和酸解总氮量基本不变,只有缺氮区土壤酸解总氮明显下降。与不平衡施肥比较,NPK处理保持了较高的酸解铵态氮和酸解未知态氮水平,同时保持了较高的水稻产量和水稻吸更多还原

【Abstract】 In this dissertation, we studied the mechanisms of nitrogen transformation and nitrogen supply to rice in paddy soils through incubation experiments, and field experiments. A long-term fertilization experiment was conducted with researching optimal nitrogen application for rice in Jinhua, Zhejiang Province of China. Information provided in this work may contribute to a better understanding of soil nitrogen supply capacity in paddy soil environment, which will be useful reference for reasonable fertilizer application. Main original conclusions are shown as follows.（1） Dynamics of grain yields and nutrient uptake of rice, and the ecological characteristics of microorganism of the paddy soil were investigated in a long-term split-block experiment with different fertilization treatment, including control （CK）, PK, NK, NP, NPK fertilization, in the main block, and conventional rice and hybrid rice comparison, in the sub block. The results showed that grain yield of rice was positively correlated with N uptake, P uptake and K uptake（r=0.7353**, 0.5461**and 0.5599**, respectively）, and soil available nutrient pool depletion might occur very fast under consecutive crops grown without fertilizer application. The results also showed that microbial biomass N varied from 33.78⁷0.44 mg kg^-1, about 2.04 percent of total soil nitrogen. The soil microbial biomass N showed a marked increase in the NPK treatment as compared to values in the unbalanced nutrient treatments （NP, PK and NK）. CK treatment could also support a higher level of soil microbial biomass N. The results of BIOLOG showed that in the first 32h of incubation, AWCD changed very little but afterwards AWCD increased continuously. At the same time, AWCD of NPK treatment was the highest in all treatments. AWCD of CK treatment increased gradually and were higher than that of NP, PK and NK treatments at the late stage of incubation. It was showed here that soil nutrient deficiency andunbalanced fertilization to rice crop had a negative effect on the diversity of the microbial community and total microbial biomass in the soil. We concluded that balanced application of N, P and K increased microbial community and total microbial biomass of the soil. Unbalanced fertilization reduced microbial N and increased C/N ratio of the microbial biomass.（2） Changes of soil organic nitrogen forms and soil nitrogen supply under continuous rice cropping were investigated through the long-term NPK experiment. It was found that after 6 years of continuous double-rice cropping, the soil total N and hydrolysable N contents were maintained in the N-supply plots, while the hydrolysable N contents were substantially reduced in the N omission plots. Balanced application of N, P and K promoted the percentages of hydrolysable ammonium N in the total N compared to the unbalanced fertilization treatments, also maintained higher rice grain yield and nitrogen uptake. It was found that grain yield was positively correlated with total N uptake, hydrolysable N, hydrolysable ammonium N and HUN fraction N （r = 0.875 , 0.608 , 0.560 , and 0.417**, respectively）; total N uptake was positively correlated with hydrolysable N, hydrolysable ammonium N and HUN fraction N （r = 0.608* , 0.440 , and 0.431 , respectively）. The hydrolysable N had contribution to rice grain yield and N uptake.（3） In this paper, the chemical group components in soil humic acids（HA） and fulvic soids（FA） isolated from soil of different fertilization treatments were studied by using infrared spectrum（IR） and *H nuclear resonance spectroscopy（NMR）, and it was also researched the effect of different fertilization treatments on chemical groups structure of humic substance. The IR analysis of HA indicated that polycondensation and conjugation of the unstaturated structure and the content of aromatic compounds in HA isolated from the long term no fertilization soil increased, while aromatization degree and simple organic molecular fraction in HA isolated from fertilization soil increased, and effect was NPK> PK. It was found that there were more aliphatic groups and less sugar components in HA extracted using O.lmol/L Na4P2O7 and O.lmol/L NaOH compared with HA extracted only using O.lmol/L NaOH. The ’H NMR results showed that the positions of the major spectral bands of these NMR spectra were similar to each other, and it was found the effect of different fertilization treatment on carbon-H and aliphatic-H were NPK>CK>PK and PK>CK>NPK.（4） Direct-seeding for early rice as a laborsaving technique has been spreading rapidly in the past several years in Zhejiang Province. The agronomic performance of a newly developed site-specific nutrient management （SSNM） technique was tested against the farmer’s fertilizer practice （FFP） in更多还原