【作者】 杨玲；

【导师】 廖允成；

【作者基本信息】 西北农林科技大学 ， 生态学， 2011， 硕士

【摘要】 农田土壤既是CO₂的重要排放源又是CO₂的吸收汇,在温室气体减排方面起着非常重要的作用,保护性耕作能够有效降低土壤CO₂的排放,增强土壤碳汇的作用。为了探讨保护性耕作对土壤CO₂排放通量的影响,本试验以旱地冬小麦为研究对象,共设了翻耕（T）、翻耕+秸秆还田（TS）、旋耕（RT）、旋耕+秸秆还田（RTS）、免耕（NT）、免耕+秸秆覆盖（NTS）6种处理,系统研究了保护性耕作对土壤CO₂排放通量、土壤微生物量碳、氮以及小麦产量的影响,进一步分析了CO₂排放通量与土壤水、热的相互关系。主要结论如下:1.土壤呼吸通量有明显的日变化规律,各天气状况下呼吸通量表现为:晴天>多云>阴天。晴天土壤呼吸峰值出现在13:00左右,多云和阴天稍晚一些,大约出现在14:00-15:00之间,各天气土壤呼吸最低值均出现在凌晨5:00左右。2.土壤呼吸通量在整个小麦生育期随着温度的升高而升高,表现为夏季高冬季低的规律。在整个变化过程中共出现三个峰值,分别是小麦播种期、拔节期和灌浆期,土壤呼吸通量最低值出现在越冬期。3.少耕和免耕能有效降低土壤呼吸通量,并以免耕效果更为显著;秸秆还田表现为增加土壤呼吸的作用。整个小麦生育期,不同耕作处理下土壤呼吸通量的顺序为:TS>T>RTS>RT>NTS>NT。4.各耕作措施下土壤呼吸通量与各层地温均呈极显著正相关关系,翻耕方式与15cm土壤温度相关性最好,旋耕方式与5cm相关性最好,免耕方式与各层土壤温度相关性差别不大。各层土壤温度与土壤呼吸通量的拟合二次方程优于指数方程。5.免耕、秸秆覆盖有很好的保水蓄水作用,并且表层保水作用优于深层。土壤水分含量与土壤呼吸通量之间没有显著相关性,未表现出明显规律性。6.整个小麦生育期,各处理土壤微生物量碳均呈单峰变化曲线,播种期土壤微生物量碳含量最小,扬花期最大。免耕和少耕能显著增加土壤表层微生物量碳。0-10cm土层,NTS、RTS、NT、RT、TS分别较T处理土壤微生物量碳增加37.3%、33.15%、19.8%、8.74%和7.65%;10-20cm土层,TS、RTS、RT、NTS、NT分别较T微生物量碳的增减为7.62%、4.92%、-1.84%、-14.5%、-17.9%。7.各耕作措施下0-10cm土层土壤微生物量氮均显著高于10-20cm土层土壤微生物量氮。0-10cm土层中,保护性耕作能有效增加土壤微生物量氮含量,并以免耕和免耕覆盖效果较优。NTS、NT、RTS、RT、TS分别较T处理增加54.8%、32.4%、20.8%、13.9%、7.8%。10-20cm土层各处理土壤微生物量氮差异较小。8.免耕方式能明显增加小麦穗粒数和千粒重;旋耕有利于有效穗的形成,增加小麦千粒重。秸秆还田有利于有效穗的形成,但穗粒数和千粒重与无秸秆处理的差别不大。免耕在耕作年限较短情况下明显降低小麦的理论产量和实际产量。更多还原

【Abstract】 The soil of farmland is both an important source of CO₂ emission and the sink of CO₂, it plays a very important role in reducing the greenhouse gas emissions. The conservation tillage can reduce CO₂ emissions of soil, and enhance to sink of carbon in soil. To investigate the conservation tillage practices on soil CO₂ emission flux, the experiment, with winter wheat as the research object, sets 6 treatments: tillage （T）, tillage + straw （TS）, rotary tillage （RT）, rotary tillage + straw （RTS）, no-tillage （NT）, tillage + straw （NTS） , this experiment studies the influence on soil CO₂ emission rates, soil microbial biomass carbon, nitrogen, wheat yield of different tillage, and analyzes the relation of soil temperature and moisture on CO₂ emission flux . After study, the main conclusions are as follows:1. Soil respiration flux has obvious day change; the emission flux is the highest when it’s sunny, second when there are many clouds, and minimum when cloudy. The soil respiration flux showed a single peak trend under every weather conditions. The peak appears at around 13:00 on sunny days, a little bit later when cloudy between 14:00-15:00, and the minimum value of soil respiration occurs at 05:00 am.2. Soil respiration flux shows a regular performance in the entire wheat growth period : high in summer and low in winter. Throughout the whole changing process there are three peaks, they are wheat sowing period, jointing period and filling period. And the lowest value appears in winter period.3. Minimum tillage and zero tillage can reduce soil respiration flux, and a more significant effect with the second one, besides, straws can increase the soil respiration. In the entire wheat growth period, soil respiration flux performs in the following order: TS> T> RTS> RT> NTS> NT.4. Throughout the entire growth period of wheat, the soil temperature show first descend and then increase; the minimum value appears in winter period, the highest in the sowing period. Within different tillage, the respiration flux of soil and soil temperature are highly positive correlation, T and NT have the best correlation with 15cm’s soil temperature, and RT has the best correlation with cm’s soil temperature. The ffititting equation of temperatures and soil respiration flux is the quadratic equation better than the index. 5. With the increase of depth of soil, the soil water content firstly increases and then decreases, and stays stable after the 40cm depth. Zero tillage and straw mulch have a good effect of water storage and the ability of water storage in the surface is superior to the deep slayer. Soil water content and soil respiration flux are not significantly correlated and no obvious regularity.6. Within the entire wheat growth period, soil microbial biomass carbon in each treatment shows a single peak curve, at the sowing period, soil microbial biomass carbon has the minimum content, maximum when flowering period. Zero tillage and minimum tillage can significantly increase the microbial biomass carbon on the soil surface. At 0-10cm soil layer, NTS, RTS, NT, RT and TS compared with T the microbial biomass carbon increased 37.3%,33.15%, 19.8%, 8.74% and 7.65%. At 10-20cm soil layer, TS, RTS, RT, NTS and NT showed respectively increase or decrease rate is 7.62%, 4.92%, -1.84%, -14.5%, -17.9%.7. At 0-10cm soil layer, soil microbial biomass N is significantly higher than that of 10-20cm. In 0-10cm soil layer, conservative tillage can increase effectively soil microbial biomass nitrogen content, and better effect for NT and NTS. Compared with T the NTS, NT, RTS, RT and TS, respectively increased 54.8%, 32.4%, 20.8%, 13.9%, 7.8%. At 10-20cm soil layer there is smaller differences in microbial biomass.8. Zero-tillage is not conducive to the formation of effective panicles of wheat, but can increase the quantity of grain and grain’s weight; Rotary tillage can increase the formation of effective panicles and the weight of wheat, but grain number is not very different from traditional farming. Straw is conducive to the formation of the effective panicles, but not conducive to increase the number of grain and the weight of grain. Zero tillage can significantly decrease the yield of wheat, when the years of zero-tillage is too short.更多还原