【作者】 张志栋；

【导师】 刘景辉；

【作者基本信息】 内蒙古农业大学 ， 作物栽培学与耕作学， 2010， 博士

【摘要】 免耕是具有保水、保土和保肥作用的一种重要耕作技术,是北方农牧交错区防风固土、涵养水分、节能减排、稳产高产的有效耕作措施之一。本研究以内蒙古阴山北麓武川县为研究区域,通过田间试验和室内测定分析方法,研究不同保护性耕作方式的旱作燕麦土壤性状和温室气体排放规律。研究结果如下：1、土壤CO2排放季节变化差异明显,CH4和N2O排放季节性差异不明显。CH4排放通量多为负值,表现为“吸收”。与传统耕作相比,免耕留茬覆盖减少了CO2排放和CH4吸收,增加了N2O排放。秸秆覆盖处理对温室气体排放的影响高于留茬高度。免耕施肥比不施肥处理增加了CO2、N2O排放和CH4吸收。氮肥对增加温室气体排放的影响较大；氮磷、氮磷钾肥配施对CO2排放和CH4吸收影响更大,而对N2O排放的影响低于单施氮肥,磷、钾肥对温室气体排放的影响较小。温室气体综合排放效应受CO2排放通量主导,CH4和N2O通量对其影响甚微。2、免耕对改变土壤水分和温度,增加土壤养分作用明显。免耕留茬覆盖处理增加了土壤水分,降低了地温。免耕留茬覆盖处理0-10cm、10-20cm和0-20cm土层平均水分含量分别比传统耕作高86.95%、46.62%和66.18%；10cm和20cm土层平均地温分别比传统耕作低2.92℃和2.02。C；在0-10cm土层有机碳、全氮、全磷均显著或极显著高于传统耕作,10-20cm土层与传统耕作相差不大。免耕施氮肥降低了土壤水分含量,增加了全氮含量,而对土壤有机碳和全磷含量影响较小；磷肥的施入增加了土壤全磷含量,而对土壤水分、有机碳、全氮影响不明显；钾肥对土壤水分、有机碳、全氮、全磷均无明显影响；施肥对土壤地温的影响极小。3、土壤酶活性季节性变化明显。免耕留茬覆盖处理土壤酶活性均显著高于传统耕作。免耕覆盖对提高土壤酶活性效果高于留茬。免耕施肥可以提高土壤酶活性,氮肥对脲酶、碱性磷酸酶和蔗糖酶活性影响最大,磷肥次之,钾肥无明显影响；钾肥对过氧化氢酶活性影响较大,氮肥对其无显著影响；氮磷、氮磷钾肥配施对土壤酶的影响大于氮磷钾肥单施。4、免耕留茬覆盖处理土壤微生物量碳、氮、磷及微生物商比传统耕作均显著增加。秸秆覆盖量对土壤微生物量及微生物商的增加效果高于留茬处理。免耕施肥土壤微生物量碳、氮、磷及微生物商均高于免耕不施肥处理；氮肥对微生物量碳、氮和微生物商增加幅度最大,磷肥对微生物量磷增加幅度最大,钾肥对微生物量及微生物商影响较小；氮磷和氮磷钾肥配施土壤微生物量及微生物商高于氮磷钾肥单施。5、土壤温室气体排放受土壤理化性状、酶活性及微生物量等多种因素影响。土壤地温、水分、养分、酶及微生物量等与土壤温室气体排放关系密切。0-10cm土层地温、有机碳与CO2、CH4和N2O排放均呈显著正相关关系,0-10cm、10-20cm土层水分、全氮与CO2、CH4和N2O排放均呈显著或极显著正相关,各土层全磷与温室气体排放相关性不显著；土壤各温室气体排放与土壤脲酶和蔗糖酶活性均表现为极显著或显著正相关,而与碱性磷酸酶和过氧化氢酶活性相关显著性不强；土壤微生物量碳、氮和微生物量商与CO2、CH4和N2O排放均呈极显著或显著正相关,土壤微生物量磷与CO2排放呈显著正相关,而与CH4、N2O排放通量相关性不显著。免耕对农田土壤性状及温室气体排放的影响是长期和比较缓慢的过程,变化特征也随着研究时间的长短有所不同。由于本文仅对试验区进行了连续两年的研究,对阐述土壤性状和温室气体排放的长期特征还有待进一步深入。更多还原

【Abstract】 No-tillage is an important farming technique which conserves soil, fertilization and water of the farmland. It is also known as the effective farming measure to fix soil, conserve water, save energy and reduce emission of CO2, and keep high and stable yield in north china. Taking the Wuchuan County in Inner Mongolia Autonomous Regional for example, this research analysed the change characteristics of ecological factors and the emission characteristics of greenhouse gases in the farmland soil using different farming methods and no-till fertilization measures. Field experiment and laboratory tests were conducted during the two-year study period. The results were as follows:1. The soil CO2 emission was significantly different and subject to the seasonal changes; the CH4 and N2O emissions were not obvious with the seasonal changes. The CH4 emission flux almost appeared to be negative and presented as "absorption". Comparing with stubble covering, no-tillage reduced the CO2 emission, the CH4 absorption and the synthesized greenhouse effect while it may increase the N2O emissions. Straw mulch treatment showed more significant influence on the greenhouse gases emissions than stubble height. The fertilization treatment increased the emissions of CO2, N2O, and the absorption of CH4, comparing with no fertilization in the no-tillage fertilizer experiment. The single nitrogen fertilizer treatment showed more influence on increasing the greenhouse gases emissions. The N-P fertilizer and N-P-K fertilizer application combined treatments showed even more influence on the CO2 emissions and the CH4 absorption; and of these treatments on the N2O emissions, the influence was lower than the single nitrogen fertilizer treatment. The phosphatic fertilizer treatment and the potassic fertilizer treatment showed less influence on the emission of greenhouse gases. The comprehensive effect of the greenhouse gases emission was majorly dominated by the CO2 flux, and it was little affected by the CH4 flux and N2O flux.2. No-tillage was effective for increasing the soil nutrient content and changing the soil moisture and temperature. No-tillage and stubble mulching treatments increased the soil moisture content and reduced the soil temperature comparing with conventional tillage. In no-tillage treatment, the average soil moisture content of three soil layer (0-10cm,10-20cm and 0-20cm) was 86.95%,46.62% and 66.18% higher than conventional tillage treatment, respectively, the average soil temperature in 10cm and 20cm depth were 2.92℃and 2.02℃lower than conventional tillage, respectively; the soil organic carbon, total nitrogen and, total phosphorus were significantly or highly significantly higher than traditional farming in 0-10cm layer, but close to 0-20cm layer. The no-tillage fertilization experiment showed that the application of nitrogen fertilizer lowered in the soil water content but increased in the total nitrogen content, while soil organic carbon and total phosphorus had no significant change; the phosphate fertilizer applied into the soil making an increase of total phosphorus content, but had no significant effect on soil moisture, organic carbon and total nitrogen; the application of potash fertilizer had no significant effect on soil moisture, organic carbon, total nitrogen and total phosphorus; fertilization had-little influence to soil temperature.3. The soil enzyme activity had been changed regularly in different season. Experiment of different tillage methods showed that the soil enzyme activity in the no-tillage with stubble covering treatment was significantly higher than that in the conventional tillage treatment. The effect by no-tillage and covering was higher than those by increasing stubble height on improving the soil enzyme activity. The no-tillage fertilizer treatment can improve the soil enzyme activity. For the activity of urease, alkaline phosphatase and saccharase, the nitrogen fertilizer treatment had the most significant effect, followed by the phosphate fertilizer treatment; the potash fertilizer treatment had no obvious effect. For the activity of hydrogen peroxide, the potash fertilizer treatment showed more influence than other treatment; the nitrogen fertilizer treatment showed no significant effect. The N-P fertilizer and N-P-K fertilizer application combined treatments had larger effect on the soil enzyme activity than the single application of N, P or K fertilizer.4. The result of different tillage method experiments indicated that the soil microbial biomass C, microbial biomass N, microbial biomass P and the microbial quotient was significantly increased under the treatment of no-tillage with stubble covering, comparing with conventional tillage methods. The effect of straw coverage treatment was better than the stubble height treatment on increasing the soil microbial biomass and microbial quotient. The soil microbial biomass C, N, P and the microbial quotient were higher under the no-tillage and fertilizer treatment than the no-tillage without fertilizer treatment. The largest increase of the microbial biomass C, N and microbial quotient was under the nitrogen fertilizer treatment. The largest increase of the microbial biomass P was under the phosphate fertilizer treatment. The potash fertilizer treatment was little effected to the microbial biomass and microbial quotient. The N-P fertilizer and N-P-K fertilizer application combined treatments had larger effect on the microbial biomass and microbial quotient than the single application of N, P or K fertilizer.5. The emissions of soil greenhouse gases are subject to the soil physical and chemical characteristics, enzyme activities, microbial biomass and many others. The research results showed that the soil temperature, moisture, nutrients, enzymes and soil microbial biomass were closely related to the emissions of soil greenhouse gases. In detail, the significant positive correlation was observed between the soil temperature (0-10cm depth) and the emissions of CO2, CH4 and N2O; the same was between the organic carbon and those three gases. The soil moisture of two different soil layer (0-10cm depth and10-20cm depth) and the total-N was significantly (or highly significant) positive correlated with the emissions of CO2, CH4 and N2O. The total-P in all soil layers was not obvious correlated with the emissions of the soil greenhouse gases. There were significant positive correlations between the two soil enzyme (urease, saccharase) activities and the emissions of soil greenhouse gases. While the correlation was not obvious on alkaline phosphatase activity and catalase activity; the microbial biomass C, microbial biomass N and microbial quotient was very significant or obvious positive correlations with the emissions of CO2, CH4 and N2O; the microbial biomass P was significant positive correlation with the CO2 emissions but was not obvious correlated with the emission flux of CH4 and N2O.The influence of no-tillage on field experiment and greenhouse gases emissions is a long and slow process. Variation characteristics are different depend on the length of study time. The exploration of soil properties and long-term emission of soil greenhouse gas needed to be improved as the experiment lasted only two years.更多还原