【作者】 向万胜；

【导师】 李学垣；

【作者基本信息】 华中农业大学 ， 土壤学， 2003， 博士

【摘要】 磷作为植物生长必需的大量营养元素，其在土壤中的转化、迁移及植物有效性一直是土壤和植物营养学家的研究热点。近年来，磷作为水体富营养化的重要控制元素影响水环境质量而日益受到人们的日益关注。提高农田土壤磷的利用率和降低磷在土壤中的累积和流失，从而减少磷对水环境的污染，对于磷肥资源的高效利用和保护环境都具有十分重要的意义。 本论文在综述了土壤磷素的化学行为与农田生态系统磷素循环国内外研究进展的基础上，通过模拟培养实验、田间调查、田间定位试验与室内分析相结合的方法，研究了华中亚热带丘岗区红壤与水稻土磷素的形态与转化特点，内容包括添加有机物料和磷酸盐对红壤与水稻土微生物量磷和无机磷形态转化的影响，施用有机肥料、水旱轮作与地下水位变化对水稻土微生物量磷、无机磷形态及磷素有效性的影响；同时，还对江汉平原土壤磷素的分布、形态组成与循环进行了研究。研究的重点为旱地红壤及水稻土微生物量磷的转化与土壤无机磷转化之间的关系。所取得的主要结果如下： 模拟培养试验验结果证明：(1)添加添加有机物料促进了土壤无机固定态磷的活化，土壤微生物对磷素的生物固持作用增强是其重要原因之一。添加葡萄糖和稻草极显著提高了红壤和红壤性水稻土微生物量磷含量，而土壤无机磷总量显著降低，其中红壤性水稻土主要是Fe-P含量降低，而旱地红壤主要是Al-P的降低。(2)添加葡萄糖促进了外加磷酸盐向土壤微生物量磷和其它非无机固定态磷的转化，减少了土壤无机矿物对磷酸盐的固定。在培养结束时，无外加葡萄糖碳源时所添加的磷酸盐几乎完全转化为土壤无机固定态磷；而在有外加葡萄糖碳源存在时，所添加的磷酸盐仅有46.5％转化为土壤无机固定态磷，而有53.5％转化为土壤微生物量磷和其它非无机固定态磷。 田间定位试验结果表明：(1)长期施用有机肥使水稻土微生物磷含量极大地提高，土壤易溶态无机磷组分的比例增加，提高了磷素有效性。(2)水旱轮作下土壤微生物量磷含量呈显著上升，土壤微生物对磷素的同化作用增强；水旱轮作后土壤微生物量C/P比值显著降低，指示土壤微生物对有机物料的矿化具有较大释放磷的潜力，土壤微生物量磷对土壤有效磷库的补充作用加强，故水旱轮作有利于土壤磷素的活化。 田间调查与定位观测研究结果表明：丘岗区潜育性水稻土地下水位的升降明显影响土壤有效磷的含量及土壤无机磷的形态，土壤有效磷、Fe-P和O-P均随地下水位的升高而显著下降。潜育性土壤有效磷、全磷和无机磷总量均比非潜育性土壤显著降低，丘岗区红壤性潜育化水稻土Fe-P和O-P的降低占无机磷降低总华中亚热带红攘和水稻土磷素的形态与转化过程量的89%，江汉平原长江冲积物发育的潜育性水稻土Ca一P的降低占无机磷降低总量的64%。从而揭示了土壤无机磷的损失是潜育性水稻土磷素有效性下降的重要原因之一。 农田土壤磷素循环与平衡研究结果显示:江汉平原水稻土几种主要和植制度下农田土壤磷素输入量变化在36.4一52.45 kg/hmZ.yr之间，平均为41.65kg/h mZ.yr;磷素的输出量变化在24.5~39.6 kg/hmZ.yr之间，平均为29.0kg/h mZ.yr。农田土壤磷素的输入输出均呈盈余状态，其盈余量为2.:;一27.9kg，/h mZ.yr，输入与输出量的比值(I/0)为1 .06一1 .88，指示该地区农田正发生着土壤磷素的累积。更多还原

【Abstract】 Studies on chemical transformation and translocation of phosphorous in soil and its availability to crops have been permanent research topics in soil and plant nutrition science since phosphorous is distinguished to be one of the essential macro nutrients for plant growth. With an increasing concern on environmental issues in recent years, phosphorous as a key chemical element for eutrophication control has been focused by more and more environmentalists. From viewpoint of both high efficient use of resources and environment protection, it is of great significance to increase utilization of phosphorous by plants, decrease phosphorous accumulation in soil and reduce phosphorous loss from soil.Based on a review of research development on chemical behaviors of phosphorous in soil and its cycling in agroecosystem, this dissertation dealt with chemical fractions, transformation and cycling of phosphorous in red soil and paddy soil of subtropics in central China, using techniques of laboratory incubation, field investigation and field experiments. Research aspects contained effects of organic material and phosphate addition on transformation of microbial biomass P and inorganic P fractions in red soil and paddy soil, effects of different fertilizer treatments, paddy-upland rotation and changes of groundwater level on microbial biomass P, inorganic P fractions and its availability to crops, as well as distribution, inorganic fractions and cycling of phosphorous in an alluvial plain etc. Emphasis was focused on the relation of changes of microbial biomass P to inorganic P transformation in soil. The main results were showed as follows:(1) Incubation experiment by using the paddy soil developed from Quaternary red soil showed that total inorganic P in paddy soil with organic materials addition(glocuse and rice straw) significantly decreased compared to the control without organic materials addition, where the decrease of total inorganic P was dominantly caused by release of iron phosphate (Fe-P) . On the other hand, soil microbial biomass P was significantly raised by organic materials addition. So it was suggested that possibly phosphorous immobilization mediated by soil microorganisms resulted in the release of phosphorous fixed by soil inorganic particles.(2) Incubation experiment by using the upland red soil derived from Quaternary red clay indicated that total inorganic P in red soil was also significantly reduced and microbial biomass P was markedly raised by glucose addition. What was different from the case in paddy soil was that total inorganic P decrease was dominated by Al-Pdecrease, accounting for more than 60% of total inorganic P decrease. Following 60 days incubation, almost all the phosphate added into the soil in the treatment cf single phosphate addition was transformed into inorganic P forms fixed by the soil minerals. However, in the treatment of phosphate combined with glocuse addition, only 46.5% of applied phosphate was transformed into inorganic P forms fixed by soil inorganic minerals and 53.5% of that was transformed into other forms of phosphorous non-fixed by soil inorganic minerals such as microbial biomass P. It was assumed that addition of organic carbon into upland red soil stimulated the transformation of applied phosphate into microbial biomass P and other forms of phosphorous non-fixed by inorganic minerals, and possibly reduced the fixation of applied phosphaU by soil inorganic minerals.(3) Long-term field experiments proved that microbial biomass P in pacdy soils were greatly raised by long-term application of organic manure combinsd with chemical fertilizer, otherwise, there were minor or no increase of microbial bi Dmass P in paddy soils under the condition of long-term application of single chemical fertilizer. Both Al-P and Fe-P as a percentage of the total inorganic P presented an increase tendency and O-P as a percentage of the total inorganic P showed a decrease tendency in all the treatments with organic manure application. Thus, it was concluded that organic m更多还原