【作者】 杨芳；

【导师】 田霄鸿；

【作者基本信息】 西北农林科技大学 ， 植物营养学， 2011， 硕士

【摘要】 Zn作为动植物所必需的微量元素,通过植物进入食物链后,直接或间接的通过动物进入人类的膳食中,从而影响人体的营养平衡及身体健康。陕西关中地区土壤属于潜在性缺Zn土壤,该土壤中Zn供给不足、土壤的供Zn能力低下,农作物和畜产品的产量和品质都受到较大的影响。解决潜在性缺Zn土壤供Zn不足问题最有效的途径即提高土壤有效Zn含量,提高土壤的供Zn能力,进而提高农作物籽粒Zn含量,保障人体健康。陕西关中地区以小麦-玉米一年两熟轮作制度为主要的种植模式。该种植模式下每年产生大量的小麦和玉米秸秆,这些秸秆大部分没有被有效利用,造成大量的资源浪费。目前,有机肥的投入在逐渐减少,秸秆还田日益受到重视,秸秆可能代替有机肥成为进入土壤的主要有机物料。秸秆还田不仅解决资源浪费问题,同时对于保护生态环境也具有重要意义。众所周知,秸秆中富含微量元素,Zn就是其中之一,Zn和其他微量元素可随秸秆还田而归还到土壤中,增加土壤中的Zn和其他微量元素含量。本研究采用两个室内模拟秸秆（小麦秸秆和玉米秸秆）还田培养实验,通过测定土壤全Zn、有效Zn、微生物量Zn、各形态Zn含量等指标,研究了秸秆还田降解对本身所含Zn的释放、对土壤原有Zn和外源施入Zn形态转化以及对土壤微生物量Zn含量的影响,为大田推广提供理论依据。本研究得到以下主要结果:（1）为探讨秸秆在土壤中腐解对其本身所含Zn的释放及其对土壤原有Zn、外源施入Zn形态转化以及对微生物量Zn（Mic-Zn）含量的影响,进行了为期42 d的小麦秸秆腐解室内培养试验。结果表明,秸秆在土壤中腐解时CO₂-C累积释放量和土壤微生物量碳（Mic-C）随着秸秆添加量的增加而显著增加,而秸秆自身Zn含量高低以及外源施Zn对其均无明显影响。土壤中无论是否添加秸秆,施入外源Zn均明显增加了土壤Mic-Zn和土壤有效Zn（DTPA-Zn）含量,土壤交换态Zn（Ex-Zn）和松结有机态Zn（Wbo-Zn）含量也明显增加;与低Zn秸秆相比,高Zn秸秆在土壤中腐解可明显增加土壤Mic-Zn和DTPA-Zn含量,提高土壤Ex-Zn和Wbo-Zn比例。而且,秸秆腐解本身释放的Zn主要转化为有效性较高的Ex-Zn。（2）通过室内模拟培养实验,探讨了玉米秸秆腐解对自身Zn释放、土壤原有Zn和外源施入Zn形态转化及其对土壤Mic-Zn含量的影响。结果表明,为期42 d的室内培养,秸秆在土壤中腐解时,CO₂-C累积释放量随着秸秆添加量的增加平均增加了38.69%,而秸秆自身Zn含量高低以及外源施Zn对其无明显影响;土壤Mic-C含量随秸秆添加量的增加而增加,与秸秆自身Zn含量高低以及外源施Zn与否无关。土壤中无论是否添加秸秆,施入外源Zn时,土壤Mic-Zn和土壤DTPA-Zn含量分别较对照增加228.42%和131.51%,土壤Ex-Zn和Wbo-Zn含量也明显增加;与低Zn秸秆相比,高Zn秸秆在土壤中腐解时,土壤DTPA-Zn含量增加了25.06%,土壤Ex-Zn和Wbo-Zn含量也有所增加。而且,秸秆在石英砂中腐解,即秸秆腐解本身释放的Zn主要转化为有效性较高的Ex-Zn。（3）为探讨秸秆腐解对土壤供Zn能力的影响,将小麦和玉米秸秆添加到土壤中,在相同的条件下分别进行了为期42 d天的室内培养。结果表明,小麦和玉米秸秆在土壤中腐解,其CO₂-C累积释放量和土壤Mic-C、N均随着秸秆添加量的增加而增加,秸秆自身Zn含量高低和外源施Zn对其无明显影响。相同培养条件下,土壤环境加速了小麦秸秆的腐解,培养介质对玉米秸秆腐解无明显影响。土壤施Zn时土壤Mic-Zn和DTPA-Zn含量均明显增加,高Zn含量的小麦和玉米秸秆在土壤中腐解也较为明显增加了二者的含量,土壤中添加秸秆并配施Zn肥较仅添加秸秆明显提高土壤Mic-Zn和DTPA-Zn的含量。小麦和玉米秸秆添加到土壤或石英砂中均明显增加了Ex-Zn的含量,两种秸秆在土壤中腐解,土壤全Zn和各形态Zn含量均不同程度增加,Wbo-Zn则明显增加。总之,秸秆腐解过程中,CO₂-C累积释放量和土壤Mic-C、N含量随着秸秆添加量的增加而增加,秸秆Zn含量和外源施Zn对其无明显影响;土壤施Zn和高Zn秸秆腐解明显增加土壤Mic-Zn、全Zn、DTPA-Zn以及各形态Zn的含量,秸秆腐解明显提高土壤有效Zn含量,提高对有效Zn贡献较大的有机态Zn的含量,因此提高了土壤的供Zn能力。更多还原

【Abstract】 Zn is an essential micronutrient for plant and animal, it enters into the food chain through plant, and it enters the diets of human being directly or through animal indirectly, so the balance of nutrition and the health of human being are affected by zinc. Soil in central Shaanxi area is potentially Zn-deficiency, yield and quality of field crop and animal products are affected because of under supplying of soil zinc and low zinc supply capacity of soil. The most effective approach to solve zinc deficiency in soil is to increase the content of soil available Zn and soil Zn supply capacity.Wheat-maize rotation system is the main cropping pattern in central Shaanxi area. There is quite a lot of wheat and maize straw produced every year, and most of them are not effective used, which caused waste of resources. Nowadays, organic fertilizer input into soil is gradually decreased and straw return back to soil is gradually concerned, straw will be the main organic fertilizer put into soil. It is of great significance for straw returning to soil that it not only solves the resources waste problem, but also protects eco-environment. As we all know, straw contains substantial quantity of secondary and micro-nutrients, such as Zn. These nutrients can return back to soil as the crop straw return to field, and the soil fertility is increased.Two incubation experiments were carried out separately, and through the determination of soil total Zn, available Zn, Zn fractions etc. to study the effects of straw （wheat or maize straw） decomposition on Zn released from straw, the changes of forms of Zn fractions and the content of soil microbial biomass Zn （Mic-Zn）. The primary results are as follows:（1） It is of vital significance to evaluate the contribution of straw returning to farmland to keep Zn nutrient balance in soils. In order to study the effects of straw decomposition on Zn released from straw, the changes of forms of Zn fractions and the content of soil microbial biomass Zn （Mic-Zn）, an incubation experiment was carried out in dynamic microcosms for 42 days. The results showed that, the cumulative amount of CO₂-C evolution and the content of soil microbial biomass C （Mic-C） were significantly increased as the straw added to soil increased, but they were unrelated to Zn concentration in straw and whether Zn fertilization was conducted or not. Whether the straw was added in soil or not, the contents of soil Mic-Zn, DTPA-Zn, exchange Zn （Ex-Zn） and loosely organic bound Zn （Wbo-Zn） were significantly increased when Zn fertilizer was added, and these four Zn fractions were also increased to some extent when high Zn concentration straw added to soil compared to low Zn concentration straw.（2） An incubation experiment was carried out in dynamic microcosms for 42 days to study the effects of straw decomposition on Zn released from straw, the changes of forms of Zn fractions and the content of soil Mic-Zn. The results showed that, the cumulative amount of CO₂-C evolution was significantly increased by 38.69% on average as the straw added to soil increased, the content of soil Mic-C was also increased, but they were unrelated to Zn concentration in straw and whether Zn fertilization was conducted or not. Whether the straw was added in soil or not, the contents of soil Mic-Zn and DTPA-Zn were increased by 228.42% and 131.51% when Zn fertilizer was added compared to the control, Ex-Zn and Wbo-Zn were also significantly increased. The contents of soil DTPA-Zn was increased by 25.06% when high Zn concentration straw added to soil compared to low Zn concentration straw. The contents of soil Ex-Zn and Wbo-Zn were also increased to some extent.（3） Two incubation experiments were carried out separately under the same conditions in dynamic microcosms for 42 days to study the effects of straw decomposition on soil Zn supply capacity. The results showed that, the amount of CO₂ evolution was significantly increased as the wheat or maize straw added to soil increased, the content of soil Mic-C and soil microbial biomass N（Mic-N） were also increased, but they were unrelated to Zn concentration in straw and whether Zn fertilization was conducted or not. Wheat straw decomposition was accelerated in soil, while maize straw decomposition was unrelated to the incubation medium. Whether the straw was added in soil or not, the contents of soil Mic-Zn and DTPA-Zn were increased when Zn fertilizer was added, and the content of both were also increased when high Zn concentration straw added to soil. The content of Ex-Zn was increased whether the straw decomposited in soil or in quartz sand, and the content of soil total Zn and other fractions of Zn were significantly increased when straw was added in soil, especially the Wbo-Zn.In conclusion, the cumulative amount of CO₂-C evolution and soil Mic-C and Mic-N were increased as the straw added to soil increased, and they were unrelated to Zn concentration in straw and whether Zn fertilization was conducted or not; Whether the straw was added to soil or not, the contents of soil Mic-Zn, soil total Zn, DTPA-Zn and the fractions of Zn were increased when Zn fertilizer was added. The content of DTPA-Zn was significantly increased because of straw decomposition, and so did soil Wbo-Zn, therefore soil Zn supply capacity was increased.更多还原