Effects Of Conservation Tillage On The Emission Of CO₂ Flux And The Analysis Of Soil Temperature And Moisture On The Emission Of CO₂ Flux

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.