【作者】 杨曾平；

【导师】 郑圣先；

【作者基本信息】 湖南农业大学 ， 植物营养学， 2011， 博士

【摘要】 本文以农业部衡阳红壤环境重点野外科学观测基地长期冬种绿肥稻田为平台,研究了双季稻种植下长期冬种油菜、紫云英、黑麦草等不同绿肥对红壤性水稻土的主要物理性质、水稳性团聚体含量与分布、耕层土壤各粒径水稳性团聚体内有机碳和氮素的含量与分布及储量、土壤肥力特征、微生物特性及酶活性和生产可持续性的影响,探讨长期冬种绿肥一紫云英、黑麦草和油菜等对双季稻种植下红壤性水稻土质量的影响及其评价,为提升红壤性水稻土肥力和土壤质量,提高农田利用率以及发展提高水稻土养分利用效率的可持续性有效技术提供理论依据。主要研究结果如下：长期冬种绿肥的稻-稻-油菜(R-R-RP)、稻-稻-紫云英(R-R-MV)和稻-稻-黑麦草(R-R-RG)处理土壤容重显著地低于稻-稻-冬闲(R-R-WF)处理,而孔隙度、耕层土壤田间持水量以及不同上水势(-10,-33和-100 kPa)下的持水量显著地高于R-R-WF处理。长期冬种绿肥处理的土壤团聚体的平均重量直径和标准平均重量直径也高于长期冬闲处理。与R-R-WF处理相比,R-R-RP、R-R-MV和R-R-RG处理0.25-5mm水稳性团聚体的含量明显要高。在同一粒径下R-R-RP、R-R-MV和R-R-RG处理团聚体稳定性大于R-R-WF处理。游离结合态C和与R2O3结合态C与土壤团聚体的稳定性呈显著相关。R-R-RP、R-R-MV和R-R-RG处理有机碳主要富集在1-5mm粒径的水稳性团聚体内,其次在>5mm粒径的水稳性团聚体内,而R-R-WF处理有机碳则主要富集在>0.5mm粒径水稳性团聚体内。全N主要富集在较大粒径水稳性团聚体内,尤其是>2mm粒径水稳性团聚体内。证明大粒径水稳性团聚体在土壤全N的转化过程中起着十分重要作用,大粒径水稳性微团聚体对土壤有机碳、氮具有强富集和物理保护作用。长期冬种绿肥的R-R-RP、R-R-MV和R-R-RG处理水稳性团聚体内的有机碳和全N含量明显高于R-R-WF处理。大粒径团聚体内C/N比小粒径团聚体内的高,且以2-5mm粒径团聚体内的C/N为最高,从总体上来看,C/N随土壤团聚体粒径的减小而呈下降的趋势。长期冬种绿肥处理可提高2.5mm粒径团聚体C/N,对其它各粒径团聚体C/N的影响不大。所有处理>5mm粒径水稳性团聚体和<0.25mm粒径水稳性微团聚体的土壤有机碳和全氮储量较高,长期冬种绿肥尤其是紫云英绿肥可提高<5mm各粒径水稳性团聚体内有机碳和全N储量。R-R-RP、R-R-MV和R-R-RG处理土壤的土壤全有机碳(TOC)、活性有机质(LOM)、全氮(TN)、速效氮(AN)、缓效钾(SLK)和速效钾(AK)含量均高于R-R-WF处理,但土壤pH值下降,且电导率变化差异不明显。长期冬种绿肥翻压处理,上述土壤养分状况比冬季休闲处理都得到了明显的改善,长期冬种紫云英翻压处理效果最为明显。长期双季稻冬种绿肥处理的生产力高于长期双季稻冬闲处理,同时长期双季稻冬种绿肥翻压向处理土壤归还的有机物多于长期双季稻冬闲处理,土壤全有机碳和活性有机质明显提高。R-R-RP、R-R-MV和R-R-RG处理可显著增加土壤细菌、真菌和放线菌数量,不仅土壤微生物种群数量高于R-R-WF处理,微生物生物量碳和土壤呼吸也显著高于R-R-WF处理,而代谢熵低于R-R-WF处理。长期双季稻冬种绿肥可以保持和提高土壤的微生物学特性,提高土壤的生物特性。长期冬种油菜、紫云英和黑麦草在增强酶活性方面存在差异。总体来看,长期冬种紫云英处理的土壤脲酶、转化酶和脱氢酶活性高于长期冬种油菜和黑麦草处理,说明长期冬种紫云英翻压入土可为水稻稳产高产创造更好的生物化学环境。相关分析表明,微生物种群数量、微生物生物量、脲酶、脱氢酶与土壤全有机碳、全氮、速效氮、缓效钾和速效钾呈密切相关；细菌、真菌、放线菌、微生物生物量碳和代谢熵与水稻产量呈极显著相关。R-R-RP、R-R-MV和R-R-RG处理提高了可持续产量指数(SYI)和偏生产力(PFP),能明显地改善红壤性水稻土的养分状况,提高土壤健康和土壤肥力,提高红壤性水稻土生产的可持续性。粮食产量变化趋势、SYI和PFP可以作为衡量长期肥料管理的理想工具。土壤全有机碳(OC)含量,与肥料管理措施对产量的影响的一致性最小。采用非线性评价模型对28年双季稻种植下连续冬种绿肥对土壤质量的影响进行了评价,选择土壤容重(BD)、最大持水量(MWHC)、孔隙度(POR)、标准化平均重量直经(MNWD)、pH、阳离子交换量(CEC)、有效养分、土壤有机质(SOM)、微生物生物量碳(MBC)、土壤酶和作物生产力等参数作为评价指标,并根据不同指标所具有的功能归纳为：1)抗物理退化；2)养分供应和贮藏；3)抗生物化学退化；4)保持作物生产力的能力。以以上4项功能指标为基础划分土壤质量指数(SQI)。结果证明,冬种绿肥处理条件下土壤抗物理退化、土壤养分供应和贮藏、抗生物化学退化和保持作物生产力的功能都明显强于冬闲处理。R-R-RG处理土壤抗物理退化功能最强；R-R-MV土壤养分供应和贮藏功能最强；抗生物化学退化功能,R-R-MV处理和R-R-RP处理最强；保持作物生产力功能R-R-RP处理最强。四个处理的SQI等级范围为0.552 (R-R-WF处理)到0.632(R-R-MV处理),R-R-MV处理的SQI值和土壤功能等级最高,三个冬种绿肥处理都明显高于冬闲处理。长期冬种绿肥可明显改善红壤性水稻土土壤物理、化学和生化性质,从而提高了土壤的综合质量。更多还原

【Abstract】 A long-term field experiment was conducted to study the effect of long-term inputs of green manure on soil physical properties, content of water-stable aggregates and its size distribution, content and distribution and storage of aggregate-associated organic carbon and nitrogen, characteristics of soil fertility, microbial properties, enzyme activities, Sustainable productivity and soil quality of a reddish paddy soil based on a double cropping system from Key Field Monitoring Experimental Station for Red Soil Eco-environment of Ministry of Agriculture, Qiyang County, Hunan, China. It can provide the theoretical basis for improving the soil fertility and soil quality in the reddish paddy soil, the utilization of farmland, and developing the sustainable and effective technology to improve the nutrient use efficiency. The main results were as follows:The soil bulk density in all green manure treatments was significantly reduced compared with the winter fallow treatment. Soil porosity under green manure applications was significantly higher than under the winter fallow. The 0.25-5 mm water stable aggregates and aggregates stabilities in the plow layer (0-15 cm depth) were higher in green manure treatments than in the fallow treatment. The mean weight diameter and normalized mean weigh diameter of aggregates were larger in the green manure treatment than in the winter fallow treatment. Soil given green manure retained both a higher water holding capacity in the plow layer soil, and a larger volume of moisture at all matric potentials (-10,-33 and -100 kPa). The free and weakly combined C and R2O3-combined C were significantly correlated with the stability of soil aggregates.Organic carbon is mainly enriched in 1-5mm water stable aggregates, followed by the >5mm water stable aggregates after a long-term winter planting green manure, and organic carbon is mainly enriched in >0.5mm water-stable aggregates in long-term winter fallow plot treated. Total N is mainly enriched in the larger size water-stable aggregates, in particular,>2mm water-stable aggregates, which indicated that large-size water-stable aggregates plays an important role in transformation of soil total N. Large-size water-stable micro-aggregates have a strong enrichment and physical protection on soil organic carbon and nitrogen. Long-term winter planting green manure can increase the content of organic carbon and total N of water-stable aggregates. C/N ratio of large aggregate is higher than that of small aggregate, C/N ratio of 2-5mm aggregate is the highest, C/N ratio is decreasing tendency with the decrease of particle size of soil aggregates. Long-term winter planting green manure treatment can improve C/N ratio of 2-5mm aggregates, and which has little effect on the C/N ratio of other size aggregates. Soil organic carbon and nitrogen stocks higher in >5mm water-stable aggregates and <0.25mm water-stable micro-aggregates in all plot treated. Long-term winter planting green manure, especially Chinese milk vetch can improve the storage of <5mm aggregate-associated organic carbon and nitrogen.Long-term winter planting green manure incorporation treatments increased soil total organic carbon (TOC), liable organic matter (LOM), total nitrogen (TN), available nitrogen (AN), slowly available potassium (SLK) and available potassium (AK) compared with the R-R-WF treatment. The soil nutrient status in treatments with long-term winter planting green manure incorporation were significantly improved compared with the winter fallow treatment; all these properties in the treatment with winter planting Chinese milk vetch were the most obvious. In the meantime, long-term winter planting green manure incorporation treatments could significantly decrease the soil pH in the Typic Hapllc-Stagnic Anthrosis (pH6.6 in initial soil). The productivity of long-term winter planting green manure plots treated was higher than that of the winter fallow-treated plots. Compared with the winter fallow-treated plots, the organic matter returned to the soil, soil organic matter and labile organic matter were higher in the winter planting green manure plots treated.The amounts of microbial populations, microbial biomass carbon (SMBC), microbial biomass nitrogen (SMBN), soil respiration, activities of urease, lnverstase and dehydrogenase were increased, and metabolic quotient (qCO2) was decreased in long-term winter planting green manure incorporation treatments. The microbial characteristics in the treatments with long-term winter planting green manure incorporation were significantly improved as compared with the winter fallow treatment. All these properties in the treatment with winter planting Chinese milk vetch were the most obvious. In the meantime, amounts of microbial populations, SMBC, urease and dehydrogenase were positively correlated with TOC, TN, AN, SLK and AK. Amounts of microbial populations, SMBC and qCO2 were positively correlated with rice yield.Sustainable yield index (SYI) and partial productivity (PFP) of long-term winter planting green manure treated plot was improved. Long term winter planting green manure and incorporate can significantly improve the nutrient status of paddy soil, soil health, soil fertility, and sustainable rice production of reddish paddy soil. Trends in grain yield, SYI and PFP of fertilizer appear promising tools to measure sustainability of fertilizer management practices. Soil organic carbon content, showing the least consistency with the effect of fertilizer management practice on yield, did not prove a reliable index of sustainability in this study.A soil quality index (SQI) based on four soil functions (i.e. the soil ability to resist physical degradation, supply plant nutrients and storage, resist biochemical degradation and sustain crop productivity) was derived for each treatment using bulk density (BD), maximum water holding capacity (MWHC), porosity (POR), normalized mean weight diameter (NMWD), pH, cation exchange capacity (CEC), plant available nutrients, soil organic matter (SOM), microbial biomass, soil enzymes and rice yield. The soil ability to resist physical degradation, to supply plant nutrients and storage, to resist biochemical degradation and to sustain crop productivity of the winter green manure treatments is much stronger than the winter fallow treatment. The soil ability to resist physical degradation of R-R-RG treatment is the strongest. The soil ability to supply plant nutrients and storage of R-R-MV treatment is the strongest. The soil ability to resist biochemical degradation of R-R-RP treatment and R-R-MV treatment are the strongest. The ability to sustain crop productivity R-R-RP treatment is the strongest. Soil quality index ratings ranged from 0.552(R-R-WF treatment) to 0.632(R-R-MV treatment) among the four treatments. SQI and soil functional class of the R-R-MV treatment are the highest, the three winter green manure treatments are higher than the winter fallow treatment obviously. Long-term winter planting-green manure improved the physical, chemical and biochemical properties of reddish paddy soil and therefore improved the comprehensive soil quality.更多还原