| In the context of global warming, the concentration of greenhouse gas emissions from human activities is constantly increasing. The high concentrations of greenhouse gases cause global climate changes, and a series of ecological and environmental changes such as increasing the rainfall, rising sea levels, etcetera. Therefore, it becomes a crucial issue of human survival to slow down greenhouse gas emissions. Soil respiration of the farmland ecosystem is an important part of the carbon cycle of terrestrial ecosystems. Also it is the main source of greenhouse gas emissions caused by human activities. The farmland ecosystems are more easily affected by human interference among global terrestrial ecosystems. The carbon pool is accordingly more active. Consequently the soil respiration of farmland ecosystem can affect the regional and the global carbon cycle. A variety of agricultural management practices such as tillage, fertilization, plastic mulching etc has a direct impact on soil respiration. Accounting for6percent of the total land area, The Loess Plateau is an important part of the farmland in China. Agriculture here is mainly rainfed grain production owing to60percentage of this area without irrigation. Contradictions between the reclamation and ecological protection caused by low productivity seriously restricted the local socio-economic development. Mulching with plastic is a widely used measurement of increasing agricultural production in this region. Plastic mulching measurement can effectively inhibit evaporation to significantly decline the total evaporation so as to ensure that the topsoil has a higher water content. Besides, the measurement increases the temperature of the tilth, thereupon then promotes the production.This study choose maize field as the research object in semi-arid hilly area of The Loess Plateau to explore the influence of plastic mulching to soil carbon cycle. Six treatments were established in the experiment:(1) two ridges and furrow mulched by plastic film with fertilization (DRM);(2) alternating ridges and furrows mulched by plastic film with fertilization (MINI);(3) alternating ridges and furrows mulched by plastic film without fertilization (M1N0);(4) alternating ridges and furrows non-mulched by plastic film with fertilization (M0N1);(5) alternating ridges and furrows non-mulched by plastic film without fertilization (MONO);(6) bare ground without maize planted. This paper analyzed diurnal variation of soil respiration, CO2flux in corn growth stage and how the flux effected by the environment factors under different plastic mulching and fertilization conditon.The results showed that:plastic mulching and fertilization can significantly increase the biomass of plants and crop yield. The diurnal variation of CO2flux in the region was a double-peak emission model. The mean value of CO2flux is1043-1138mg*m-2*h-1during the whole growth stage. Plastic mulching significantly promoted the soil respiration at seedling stage. The mean concentration of CO2underground is639.0-2325.5ppm. Plastic mulching promoted the production of CO2, slow down the gas emission, and significantly increased CO2production. Nitrogen fertilization had no siginficant effect on soil repiration and CO2concentration. CO2flux is collectively affected by temperature,moisture and dissolved organic carbon. The correlation analysis showed that the above factors were positively correlated to CO2flux. This experiment designed three CO2flux diurnal variation. The result showes that temperature is exponential correlated to soil respiration in the sunny weather; while temperature is polymomial correlated to soil respiration in cloudy or rainy days.In order to further understand the influence of plastic mulching on soil respiration and the interaction the factors, a process-based model of soil respiration must be established, which is the direction of future research in this study. |
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