【作者】 徐振华；

【导师】 王震宇；

【作者基本信息】 中国海洋大学 ， 环境科学， 2012， 博士

【摘要】 自20世纪80年代以来,我国就形成以氮(N)肥的大量施用来换取作物高产的农业生产模式。由于多年来N肥持续大量施用以及不合理的农业耕种、施肥制度和管理措施,导致我国北方土壤酸化日趋严重。近些年来兴起的生物炭技术为环保、高效改良酸化土壤提供了新途径。本研究针对我国北方N肥大量施用引起的土壤酸化问题,选取山东省招远市典型果园酸化土为研究对象,以我国北方典型的生物质棉花秸秆和花生壳为原料制备生物炭,研究了不同热解时间和热解温度等工艺参数对生物炭物理化学性质的影响；选择两种热解温度下制备的花生壳生物炭为供试材料,以2.5%和5%两种比例添加到酸化土壤中,研究了其对酸化土壤理化性质的影响；通过研究生物炭对酸化土壤N素转化过程的影响,初步揭示了生物炭改性酸化土壤的内在机制；通过研究生物炭对玉米植株根际效应及氮素利用有效性的影响,评价生物炭改性酸化土壤的效果,并对生物炭减少肥料施用的经济效益进行了分析和估算。本研究为建立北方酸化土壤改良的生物炭技术,最终构建生物炭的新型产业模式提供了重要的理论依据。主要研究结果如下：(1)选取我国北方典型的农业残留物棉花秆和花生壳为原料,利用慢速热解方式制备生物炭。在2h内,随着热解时间的延长,生物炭物理化学特性变化显著,当热解时间大于2h时,这种变化趋于平缓；随着热解温度的升高,生物炭产率降低,阳离子交换量(CEC)下降,表面官能团的种类及数量逐渐降低,而其灰分含量、pH、比表面积、K、Ca、Mg含量逐渐增加。(2)通过对制备生物炭的pH及CEC、产率、比表面积等特征的综合分析,当热解温度高于300℃时,花生壳生物炭的pH才表现为碱性,但高于400℃生物炭CEC值只有2.86cmol kg-1甚至更低,不宜用于酸化土壤改良,因此选择了300℃和400℃下热解花生壳制备的生物炭(H300和H400)作为酸化土壤改性研究的供试材料。(3)生物炭添加量为2.5%时,H300和H400分别使土壤容重降低了5.1%和7.1%,土壤pH分别提高了0.58和0.80个单位,有机质含量分别增加了65%和35%,CEC值分别提高了5.5%和9.0%；生物炭添加量为5%时,土壤各理化性质指标改善效果更好。(4)通过生物炭对NH4+和N03-吸附试验,表明H300和H400对NH4+有很强的吸附作用,并且当NH4+的浓度高于10mg L-1,H400的吸附能力明显高于H300；但对N03均未表现出明显的吸附作用。(5)H300和H400一方面通过吸附作用降低NH4+可利用性,减少硝化反应底物,另一方面通过减少氨氧化细菌数量,抑制了土壤中的硝化作用,进而减少了土壤中的H+释放量而提高土壤pH值,另外还可以减少土壤N素以N03-的形式而流失。(6)两种生物炭均明显促进了玉米植株的生长,以2.5%和5%添加H400后,植株干物重分别提高了30.3%和32.7%；同时玉米根系形态变化明显,根长、根尖数、根比表面积及根体积分别提高了44%和91%、51%和117%、60%和99%以及79%和108%。(7)两种生物炭H300和H400可以释放一定的N素,量非常少几乎可以忽略不计；但H300和H400能明显提高土壤N素利用有效性,以2.5%和5%的比例添加时可分别减少8.5%、13.6%、27.0%和27.7%的N肥施用量,具有很强的肥性效应。更多还原

【Abstract】 Since1980s, large amount of nitrogen fertilizer was used in order to increase crop yields to fulfill the people’s demands. Due to long-term excessive N fertilizer application, unreasonable farming system and management measures, the soil acidification in north China was getting more severely. In recent years, the rise of biochar technology provided a new environmental protection, high efficiency way for ameliorating soil acidification. Based on the soil acidification caused by excessive nitrogen fertilizer used, biochars were prepared from cotton straw and peanut hull at different pyrolysis times and temperatures, then two peanut hull biochars were selected for soil incubation and changes of physical and chemical properties of acid soil were studied with biochar amendment at ratio of2.5%and5%, separately. Through the effect of biochar on soil N transform, the mechanism of biochar amendment on acid soil was explained. Moreover, the rhizosphere effect and N utilization was studied with biochar amendment, and the economic benefit of biochar reducing fertilizer applied was analyzed and estimated. The main conclusions are as follows:(1) The typical agricultural residues in north China-cotton stalk and peanut hull were selected, and pyrolized to prepare biochar. Within2hours, the physical and chemical properties of biochars changed significantly as the pyrolysis time extended, but began to flatten when the pyrolysis time was above2hours. The biochar yield and cation exchange capacity decreased as the pyrolysis temperature rised, while the ash content, pH, surface area and the content of K, Ca, Mg increased.(2) The pH of peanut hull biochar was alkaline when pyrolysis temperature was above300℃, but the CEC was only2.86cmol kg-1which was not suitable for acid soil amendment when pyrolysis temperature was above400℃. Therefore, two biochars (H300, H400) which was obtained from300℃and400℃was selected for acid soil amendment. (3) When H300and H400were added into the acid soil at ratio of2.5%, the soil bulk density decreased by5.1%and7.1%, while the pH increased by0.58and0.80units as well as organic matters and CEC elevated by65%,35%and5.5%,9.0%, separately. The improvement of soil physicochemical properties was much more significant when the ratio of biochar was5%.(4) H300and H400could strongly absorb NH4+, and H400adsorption ability was obviously higher than that of the H300when the concentration of NH4+was above10mg L-1. However, NO3-was barely absorbed on H300and H400.(5) Through the absorption NH1+in one hand, and the amount of ammonia oxidizing bacteria decreased by H300and H400in the other hand,the nitrification was strongly inhibited. Just because of this, soil pH was arised and nitrogen was maintained.(6) The growth of maize plant was significantly promoted with two biochars amendment. The maize biomass was improved by30.3%and32.7%when H400was added into acid soil at ratio of2.5%and5%. Meanwhile, the root morphology was enhanced.(7) A small amount of nitrogen that could be neglected was released from H300and H400, but the N utilization efficiency was significantly improved with biochar amendment. The amount of nitrogen fertilizer decreased by8.5%,13.5%,27.0%and27.7%when H300and H400was used at the ratio of2.5%and5%.更多还原