【作者】 郑诗樟；

【导师】 胡红青；

【作者基本信息】 华中农业大学 ， 土壤学， 2012， 博士

【摘要】 我国长江以南地区是缺硫较严重的地区。施硫可提高作物产量和品质,但施用不当,会造成作物减产和品质降低。硫与其它元素间的交互作用及其效应方面要超过其本身的营养作用,因此,科学施用硫肥至关重要。本文以不同硫肥(单质S、硫酸根硫SO42--S)为研究对象,采用盆栽方式研究了它们对红壤和黄棕壤上水稻、油菜吸收养分的影响,探讨硫肥施入后土壤氧化还原性、土壤微生物量C、N、S和酶活性的变化,揭示了缩二脲对硫转化及对作物根系活力和养分吸收的效应,分析了硫肥与磷矿粉配施对污染土壤重金属Cd、Cu形态变化和作物生长的影响,旨在为硫肥的合理施用和重金属污染土壤原位固化技术提供科学依据。主要结果如下：1)在相同施硫量的水稻盆栽实验中,黄棕壤有效硫含量相对高于红壤,可能因为前者的Fe(Ⅲ)含量较高,氧化能力更强。红壤根表Fe含量(胶膜)高于黄棕壤,水稻吸硫量大于黄棕壤,表明根表胶膜中的硫是植物吸收硫的供应库。缩二脲与硫磺配合施用,对硫磺氧化的影响先抑制后促进,在红壤中水稻吸S量降低,黄棕壤中吸S量增加,表明缩二脲抑制了红壤根系的氧化作用,有可能生成FeS或FeS2沉淀。2)单质S在红壤与黄棕壤上的氧化受温度和水分影响。温度低于5℃时硫的氧化速率很低,干湿交替的硫氧化速率较高；随着硫磺施用量增加,其氧化速率增加。土壤氧化还原度pe+pH值在11-12之间。3)土壤pH、Eh和log[SO42-]的多元回归分析表明,红壤Eh与施S量的相关性均达极显著水平。红壤0.4g/kg SO42--S处理及黄棕壤0.4g/kg S0-S、0.2g/kgSO42--S处理油菜的生物量、根系活力和吸S量均较低。红壤0.4g/kg SO42--S和黄棕壤0.2g/Kg SO42--S处理的氧化还原体系以H2S03/S电对为主,有还原性物质产生,对油菜吸收S有不利影响。黄棕壤0.4gkg S0-S处理虽然是以H2S04/S电对为主,但其氧化还原电位与硫用量间相关不显著。4)以油菜为供试作物,测定了两种硫肥处理间土壤微生物量C、N、S和土壤基础呼吸(C02-C)的变化。随着硫肥用量的增加,土壤微生物量C、N、S和土壤基础呼吸均增加,但在苗期土壤微生物量C则降低。单质S处理油菜吸S量高于SO42--S处理,单质S的增产效果较好。根际土壤微生物量C、N、S和土壤基础呼吸低于非根际土壤,而苗期油菜根际土壤微生物量S大于非根际土壤,硫磺处理的土壤pH值变化与此相似,是影响微生物活性的重要因素。根际土壤蔗糖酶和过氧化氢酶活性低于非根际土壤,脲酶活性高于非根际土壤。土壤微生物量和酶活性对油菜吸收硫起了重要作用。5)重金属Cd、Cu污染土壤中,单施硫肥和磷矿粉时,荆芥的生物量增加的顺序为：磷矿粉处理>SO42--S处理>单质S处理,硫肥和磷矿粉配施后生物量明显高于单施。土壤重金属污染时,硫肥用量过量对作物可产生双重毒害作用。硫肥与磷矿粉作用比较,单施硫肥时重金属Cd、Cu更易向植物可利用态转变。6)不同硫肥与磷矿粉配施后,污染土壤中水溶态、交换态及残渣态Cu含量降低,水溶和交换态Cd含量增加,残渣态Cd含量降低。0.2g/kg单质S+磷矿粉处理在促进Cd2+向潜在可利用态转化的能力好于单施磷矿粉处理。种植小白菜和荆芥两茬作物后水溶和交换态Cu、Cd含量均降低,残渣态Cd、Cu增加,表明硫肥与磷矿粉配施对土壤重金属的固化有良好作用。更多还原

【Abstract】 Soil sulfur deficiency is more serious in southern of the Yangtze River in China. Sulfur fertilizers can improve crop yields and quality, and also decrease them if applied properly. And the nutritional role of sulphur is far inferior to the effects and interaction between sulfur and other elements. Therefore, it is essential that rational application of sulfur fertilizer. Pot experiments were carried out to study effects of different sulfur fertilizers (S0-S, SO42--S) on rice, rapeseed and theirs roots vigor, capacity of nutrient uptake in red and yellow brown soils, soil oxidation-reduction reaction, soil microbial biomass C, N, S and enzyme activity and the impact of biuret on paddy soil redox and rice roots vigor. Meanwhile, we explored the effect of sulfur fertilizer on different crops in heavy metal Cd, Cu contaminated soil, and the impact of application of sulphur fertilizers single and combined phosphorus rocks on Cd, Cu forms changes. These could provide a support for the rational application of sulfur fertilizer and situ immobilization technology in heavy metal contaminated soil. The main results are described as follows.(1) A rice pot experiment was conducted at the same dose of sulfur fertilizer applied, the effective sulfur content in yellow-brown soil was relatively higher than that one in the red soil, probably because the content of Fe(Ⅲ) was higher, the oxidizing ability was stronger in yellow-brown soil. Total Fe content of the plaque of root surface in:red soil> yellow brown soil, and total sulfur absorbed by the rice in red soil more than that in yellow-brown soil, which suggested sulfur in the plaque of root surface is the base of nutrient supply. Sulfur oxidation is inhibited firstly and promoted later by sulfur application mixed with biuret during the process of soil incubation. Effect of different rates of biuret fertilizer application on the S0-S fertilizer effectivity, the effectivity was reduced in red soil while enhanced in yellow brown soil with increasing rate of biuret application according to sulfur uptake by rice. Biuret might inhibit the oxidation of the root in the plaque of root surface, and led to generate the precipitation of FeS or FeS2.(2) Sulfur oxidation rate is influenced by the different temperature and moisture in the red and yellow brown soils, the rate is very low when temperature is below5℃, and is quite fast when wet and dry of soil moisture alternated frequently. And the rate also increased with increasing rates of sulfur applied. The degree of soil redox, pe+pH, was in the range of11-12。(3) Multivariate regression analysis showed that the correlation of the soil pH, Eh and log[SO42-] in red soil is better than that of the yellow-brown soil, and reached a highly significant level. There had an negative impact on rape growth, roots vigor and absorption of S amount in the0.4g/kg SO42-S treatment of the red soil and the0.4g/kg S0-S and0.2g/kg SO42--S treatment of yellow brown soil. The redox system was H2SO3/S mainly in the0.4g/kg SO42--S treatment of the red soil and the0.2g/kg SO42--S treatment of yellow brown soil, which could generate reducing substances, which had a negative impact on rape growth. Although the redox system was H2SO4/S mainly in the0.4g/kg S0-S treatment of the yellow brown soil, the correlation between soil redox potential and the rates of sulfur apllied was not significantly(4) Rape was used as testing crop, soil microbial biomass C, N, S and soil basal respiration (CO2-C) was measured. Soil microbial biomass C, N, S and soil basal respiration increased with increasing the rates of sulfur fertilizer applied, but the soil microbial biomass C decreased in the seedling stage. The content of rape uptake sulphur in the S0-S treatment was higher than that in the SO42--S treatment, which suggested that the role of increasing yield in the S0-S treatment was better. Soil microbial biomass C, N, S, and soil basal respiration in the rhizosphere soil was lower than that in the non-rhizosphere soil, but the soil microbial biomass S was greater than that of the non-rhizosphere soil in the rape seedling stage, and the soil pH of the S0-S treratments were also similar results, which showed that soil pH was a very important factor affecting the microbial activity. The invertase and catalase activities were weaker, and urease activity was stronger in the rhizosphere soil than that in the non-rhizosphere soil. Soil microbial biomass and enzyme activities played an important role in uptaking of sulfur by rape.(5) Sulfur fertilizers and phosphate rock single applied in heavy metals Cd, Cu contamination in soil, the nepeta biomass increased in following order:phosphate rock> SO42--S>S0-S treatment. The crops biomass of sulfur fertilizers combined with phosphate rock applied was significantly higher than that of two fertilizers single applied, respectively. A double toxic effect of excessive amount of sulfur fertilizer applied on crops growth in Cd and Cu combined contaminated soil. In comparison with phosphate rock, sulfur fertilizer promoted the transformation of Cu and Cd from the inactive forms to the active ones more easily.(6) Compared with phosphate rock, different rates and forms sulfur fertilizer and phosphate rock combined application could more easily decrease the contents of water soluble and exchange forms Cu, residual Cu, Cd, and increase the contents of water soluble and exchange forms Cd. The role of0.2g/kg S0-S and phosphate rock combined treatment in promoting the transformation of Cd from the active forms to the inactive ones was better than that of the phosphate rock treatment. The contents of water soluble and exchange forms Cu, Cd decreased and residual Cu, Cd increased after continuous cultivated pakchoi and nepeta, which revealed there had a good effect of sulphur fertilizers combined with phosphate rock on the Immobilization of soil heavy metals.更多还原