【作者】 李伟；

【导师】 韩娟；

【作者基本信息】 西北农林科技大学 ， 作物学， 2019， 硕士

【摘要】 生物炭作为一种新型土壤改良剂,施入土壤中改善土壤营养状况及结构,影响土壤N₂O排放,但生物炭对土壤N₂O排放及土壤理化性质的影响多集中在短期田间试验,限制了施用生物炭对土壤N₂O排放的影响效应及对土壤团聚体改良的理解。本试验依托长期田间定位试验,设置4个生物炭水平(0、5000、10000、20000kg·hm^-2分别为B0、B5、B10、B20,于2011年、2016年种植冬小麦前以相同生物炭量施于土壤中),并测定2016-2018年冬小麦生育期内土壤N₂O排放及土壤温度、水分、铵态氮、硝态氮、土壤水稳性团聚体等理化性质,研究施用生物炭对土壤N₂O排放及对土壤理化性质的影响效应,为黄土高原地区生物炭的推广提供理论基础。主要结论如下:（1）施用生物炭对麦田土壤N₂O排放的影响土壤N₂O排放主要集中在施肥后,该时期对N₂O累积排放量的贡献率较大。2016-2017、2017-2018小麦季排放高峰期对N₂O累积排放量的贡献率分别达78.23%、48.20%。由于降雨、气温的差异,2017-2018小麦季土壤N₂O累积排放量较2016-2017季降低了69.63%-83.48%。施用生物炭对土壤N₂O排放的影响因施用量和年份的不同有所差异。2016-2017小麦季,生物炭在低剂量(5000kg·hm^-2)下降低N₂O累积排放量,高量(20000kg·hm^-2)则增加土壤N₂O排放。施用高量生物炭显著增加了土壤N₂O排放强度,但其余生物炭处理与不施生物炭相比无显著差异。2017-2018小麦季,施用生物炭增加土壤N₂O累积排放量,但由于施用高量生物炭在增加小麦产量方面表现突出,该处理下土壤N₂O排放强度与不施生物炭无显著差异。（2）施用生物炭下影响土壤N₂O排放环境因子分析施用生物炭增加土壤温度,但与不施生物炭相比无显著影响。高量生物炭显著增加土壤含水量、硝态氮、铵态氮含量以及>2mm、1-2mm粒级水稳性团聚体百分含量（P<0.05）。土壤N₂O排放与理化性质的相关性分析表明2016-2017小麦季,施用生物炭处理下土壤N₂O排放与土壤含水量、铵态氮含量呈显著正相关关系,而2017-2018小麦季,施用生物炭处理下土壤N₂O排放与铵态氮、硝态氮含量呈显著正相关关系。且两年小麦季土壤N₂O排放与1-2mm水稳性团聚体百分含量呈显著正相关关系。综合两年结果表明生物炭可能主要通过影响土壤铵态氮含量及1-2mm粒级土壤水稳性团聚体百分含量影响N₂O排放。（3）施用生物炭对土壤水稳性团聚体及小麦产量的影响施用高量生物炭显著增加土壤水稳性团聚体的>0.25mm团聚体含量(R_0.25)、平均重量直径（MWD）、几何平均直径（GMD）,提高水稳性团聚体的稳定性。且施用生物炭显著提高>0.25mm粒级水稳性团聚体中有机碳、全氮的含量,有机碳和全氮含量主要富集在>2mm粒级大团聚体中。2017-2018小麦季,施用生物炭处理下土壤水稳性团聚体稳定性低于2016-2017小麦季,而>2mm粒级土壤水稳性团聚体有机碳和全氮的含量高于2016-2017季。此外,施用生物炭增加冬小麦产量,在B20处理下产量最高。更多还原

【Abstract】 As a new type of soil conditioner,biochar is applied to soil to improve soil structure and nutrition and affect soil N₂O emissions.However,effects of biochar on soil N₂O emissions and soil structure are mostly concentrated on short-term tests,which limits the understanding of effects of biochar on N₂O emissions and soil structure improvement.This experiment relies on a long-term field location experiment,and four biochar levels(0,5000,10000,20000 kg·hm^-2,B0,B5,B10,B20,respectively and the same amount of biochar was applied to the soil in 2011 and 2016 wheat season before tillage,respectively.)were set up through measuring soil N₂O emission and soil properties such as soil temperature,water,ammonium nitrogen,nitrate nitrogen and soil water-stable aggregates in the wheat season from 2016 to 2018 to study the effects of of biochar on N₂O emission and soil water-stable aggregates,which providing a theoretical basis for the promotion of biochar in the Loess Plateau.The main conclusions are as follows:（1）Effect of biochar application on N₂O emissionSoil N₂O emissions are mainly concentrated after fertilization application.The contribution rate to N₂O cumulative emission was relatively large during this period,which reached 78.23%、48.20%in 2016-2017 and 2017-2018 wheat season respectively.Due to the differences in rainfall and temperature,the cumulative N₂O emissions in each treatment in 2017-2018 wheat season decreased by 69.63%-83.48%as a whole compared with that in 2016-2017 wheat season.Effects of biochar on N₂O emission varied with application amount and year.Biochar decreased N₂O emission at low dose(5000kg·hm^-2)and increased N₂O emission at high dose(20000kg·hm^-2)in 2016-2017 wheat season.B20treatment significantly increased N₂O emission intensity,while other biochar treatments had no significant difference with B0 treatment.Biochar treatment increased N₂O emission in 2017-2018 wheat season compared with B0 treatment.However,B20 treatment showed outstanding performance in increasing wheat yield,and there was no significant difference in N₂O emission intensity in B20 compared with B0 treatment in 2017-2018 wheat season.（2）Analysis of the environmental factor of affecting soil N₂O emission in biochar applicationBiochar application can increase soil temperature,but had no significant difference compared with the control.And the application of high amount of biochar significantly increased soil water content,nitrate nitrogen,ammonium nitrogen and the contents of>2mm,1-2mm soil water-stable aggregate compared with the control.The correlation analysis between soil N₂O emission and soil physical and chemical properties showed that N₂O emission was positively correlated with soil water content and ammonium nitrogen content in 2016-2017 wheat season,while in 2017-2018 wheat season,there was a significant positive correlation between N₂O emission and soil ammonium nitrogen and nitrate nitrogen content.In addition,there was a significant positive correlation between N₂O emission and the contents of 1-2mm water-stable aggregates in two seasons.The results of the two years indicated that the biochar may affect N₂O emission mainly by changing the nitrogen content of the soil and the contents of soil 1-2 mm water-stable aggregate.（3）Effects of biochar application on soil water aggregate and wheat yieldThe application of high amount of biochar increased the values of contents of>0.25mm macro-aggregates(R_0.25)、mean weight diameter（MWD）,geometric mean diameter（GMD）of soil water-stable aggregates,and improved the stability of water-stable aggregates.In addition,the application of biochar increased the content of organic carbon and total nitrogen in>0.25mm soil water-stable aggregates,which were mainly concentrated in>2mm macro-aggregates.The stability of soil water-stable aggregates in2017-2018 wheat season was lower than that in 2016-2017 wheat season,and the content of soil organic carbon and total nitrogen in>2mm soil water-stable aggregates is higher than that of in 2016-2017 wheat season.In addition,the application of biochar increased the yield of winter wheat,and the yield of winter wheat was the highest in B20 treatment.更多还原