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 核心期刊论文目录
土地利用模式与施肥管理对红壤活性铝形态的影响
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出 版 社:中科院博士学位论文  
发表时间:2007.07  
台  站: 桃源农业生态试验站  
作  者:吕焕哲  
点 击 率:3336
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关 键 字:交换性铝;吸附态羟基铝;有机络合态铝;铝毒害;缓解;  
摘  要:土壤铝毒害是酸性土壤地区限制作物生产的主要因素,了解和掌握土壤活性铝的变化情况是缓解土壤铝毒害的前提,也是提高酸性土壤地区农业生产的基础。本研究以第四纪红土为研究对象,通过长期定位试验、盆栽土培试验以及培养试验,研究不同利用模式和施肥管理对土壤活性铝形态变化的影响,以及这些变化在作物生长上的表现。在获得上述试验资料的基础上,对结果进行分析,主要新进展如下: (1)在同种母质发育的地带性恢复林地、农作区、人工林茶园和桔园4种不同利用模式下,人工林地茶园和桔园相对于地带性恢复林地,土壤交换性铝含量增加。农田系统土壤交换性铝含量则下降,吸附态羟基铝和有机络合态铝含量提高。土壤交换性铝与土壤pH、有机质含量呈显著负相关。土壤pH是影响吸附态羟基铝的重要因素,而有机质的含量则关系到有机络合态铝含量的高低。 林地土壤表层pH值低于下层,由于枯枝落叶的影响土壤有机质表层含量较高,表层土壤交换性铝含量较低,有机络合态铝含量较高。下坡位土壤表现为堆积,土壤pH值和有机质含量均高于上坡位,降低了铝的毒性。表层土壤受人类活动和外界影响较大,表现出的差异要大于下层土壤。 (2)在酸性红壤中,铝盐导致土壤活性铝的含量明显增加,降低了作物地上部和地下部的生物量。施用酸性化学肥料具有两面性,一方面可以提高土壤中营养元素的含量,另一方面降低了土壤的pH值,导致铝离子的溶出,不利于作物的健康生长。 (3)施用稻草,土壤水溶性有机碳在第一天达到最大值,之后开始下降直至趋于平衡。土壤pH值在前10天内维持不降低或提高,添加的稻草量越高,提高的幅度也越大,之后缓慢下降至第30天渐趋平衡;土壤交换性铝含量先降低,10天后逐渐增加至稳定状态,与土壤水溶性有机碳呈显著负相关。有机络合态铝在可溶性有机碳和有机酸等小分子化合物的联合作用下,先增加而后降低。在稻草分解的前30天,土壤水溶性碳、小分子化合物和土壤pH值对铝形态的影响均较大,而到实验后期,土壤pH值发挥着主导作用。 (4)虽然稻草可以在短期内引起土壤水溶性有机碳和土壤pH值的变化,但无法使土壤有机质积累,故有机络合态铝不稳定,在外界环境变化时,易分解,不能起到很好的络合铝的作用。对玉米来讲,吸附态羟基铝是次于交换性铝的又一活性较大的铝化合物。土壤铝毒害降低后,玉米植株地上部和根吸收的P、K量增加,干物质量增加。  
关 键 字(英文):exchangeable aluminum; hydroxy aluminum; organically complexed aluminum; aluminum toxicity; alleviation  
摘  要(英文):Aluminum is the most abundant metal that makes up 7% of the earth’s crust and occurs in a number of different forms in soil. It is occurred as harmless oxides and aluminosilicates. Nevertheless, if soil pH <5 or even 5.5, as is now the case on 40% of the arable lands in the world, Al is solubilised into toxic forms, generally referred to Al3+, which is a primary factor limiting plant growth have been attributed to several physiological pathways. Calorization is an important characteristic in soil formation in tropical and subtropical area in China. Knowing active aluminum actions in the soil is the precondition to alleviate aluminum toxicity and to improve the productivity in acid soil. Take the upland soil of South China as study area, long-term location experiment, pot experiment and incubation experiment were combined together to study dynamic changes of active aluminum forms and its mechanism with the help of lab and field analysis. Long term experiment in upland soil with different utilization patterns was used to study the changes of soil physical and chemical properties and active aluminums in different planting systems. The dynamic changes of ExAl, HyAl and OrAl were analyzed in acid red soil incorporation with rice straw and aluminum, and the impacts of these dynamic changes to the growing of maize and maize biomass were also discussed. How their interactions changed soil pH and impacted the actions of active aluminum in the soil were studied by adding acid chemical fertilizer and aluminum to soil, and how these changes and impacts can be represented by the growing of maize and maize biomass, so that we can further understand the relationship and the change laws of active aluminum and soil characters, and give scientific proof to these changes impacted on the crop. With all the studies, the conclusions are as follows: (1)4 utilization patterns are in the long-term location experiments, these are, natural recuperation treatment, farming field, planted tea forest and planted orange forest. In comparison of the natural recuperation forest land, the planted tea forest and planted orange forest have low pH and high concentration of ExAl over years. While the farming field has high concentration of nutrients, high pH, low concentration of ExAl, and high concentration of HyAl and OrAl with organic material recycle. For the impacts of litter and acid rain in forest land, soil pH and soil ExAl concentrations of the surface layer were lower than that of the under layer, while the concentration of organic matter and OrAl were higher than that of the under layer. Soil pH and the concentrations of organic matter in downhill were both higher than that of the uphill position because soil corrosion piles up in the downhill position,, as a result the toxicity of the aluminum was decreased in the lower part. The surface layer of the soil differentiated greater than the under layer, because it was more affected by human activity and the outside environments. (2)Aluminum ions could increase the concentrations of the exchageble aluminum, the nutrienst absorbability was decreased, as a result both the aboveground and the underground dry matter of the crop would decrease. Two sides existed if chemical fertilizer was added to acid red soil. Firstly, it could increase the nutrients concentration in the soil; secondly it could also decrease the soil pH and induce more aluminosilicates to dissolve; therefore chemical fertilizer couldn’t ensure maize healthy growth. So organic fertilizer must be incorporated continuously, and optimal amount of chemical fertilizer was also needed at the same time, so that the nutrients concentrations in the soil and soil pH could both be improved. (3)Active aluminum forms changed remarkably in farming field because of organic material recycle. Dissolved organic matter, soil pH and active aluminum forms in soil changed rapidly within the first 30 days after straw incorporation in acid arable soil, soil pH improved rapidly within 10 days, and then it decreased to the balanced level in the next 20 days. The dissolved organic matter got its maximum value in the first day when incorporated with straw, and then it decreased quickly, and changed very slowly after 30 days. Under the influence of these, the ExAl decreased first and then rose, the more the straw was employed, the greater impacts would be on the ExAl. The changes of HyAl were very complicated and were affected by many factors, but the rapid change characteristics were still concentrated within 30 days. The OrAl rose first and then decreased; and appeared dynamic balance after 30 days. In the first stage of the straw decomposition, the dissolved organic matter, and soil pH were both have great impacts on the changes of active aluminum forms in the soil; but in the later period of the experiment, soil pH was the major factor. (4)Because of short period of straw function, soil organic matter could not be well accumulated, which could not be well complexed with aluminum, as a result the OrAl wasn’t steady and was easy to decompose when outside environment changed. As to maize, HyAl is another kind of aluminum compound with high toxicity only next to ExAl. When the aluminum toxicity was alleviated, soil nutrients absorbability improved obviously, and the root of the corn would also elongate.  
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