Abstract: Background, aim, and scope The cultivated land area in the loess area accounts for more than 15% of the total cultivated land area in China. The rainfall resources in this area are poor, soil erosion and desertification are serious, and productivity is low. Agricultural operation and management in dry land is relatively backward; it is one of the lowest areas of productivity and soil organic carbon storage in China. In recent years, there are many researches on loess area. Studies have found that a large amount of nutrition can greatly increase soil productivity. However, it is not clear about the change in CO2 emissions after nutrition is added ,and how nutrient additions change the soil environment in loess area, and then affect soil respiration and temperature sensitivity. Materials and methods In this paper, the N12 soil samples are divided into two treatments:black and phosphorate and CK soil samples are divided into four treatments black, phosphorus, carbon-entraining, and carbon phosphorus (6 treatments in total), soil basic respiration rate at 15 and 25℃ is compared and analyzed as well as the change trend of Q10 during the period of culture. Influencing factors are analyzed by comparing the changes of soil pH, total carbon and total phosphorus, organic carbon , available phosphorus, nitrate nitrogen and microbial biomass carbon and phosphorus (MBC and MBP) around respiration. Results Carbon and phosphorus increased the respiration rate of soil to a certain extent, the addition of carbon source significantly enhanced soil respiration rate and Q10..The addition of carbon and phosphorus has a increase effect on the total carbon, available phosphorus content and microbial activity, the soil microbial biomass was the highest after 15℃. After the addition of carbon and phosphorus, the soil respiration rate had a very significant correlation with soil pH, total carbon, ammonium nitrogen content and MBC . Discussion Soil respiration is an important biological indicator of soil quality and fertility, in particular, the basic soil respiration part reacts the biological activity of the soil and the strength of soil material metabolism, which reflects the transformation and supply of soil nutrients. The addition of nutrients changes the soil environment and fertility, and then increases the respiration rate and Q10. Carbon content in soil is a quick-acting substrate for microbial growth, so the addition of carbon sources promotes the activity and growth of microbes and then increases the respiration. In addition, soil pH also affect soil carbon, nitrogen and other nutrients then influence CO2 emissions. Conclusions To sum up, the addition of carbon and nitrogen changes soil environment, such as soil pH, total carbon, ammonium nitrogen and MBC, which changes soil respiration rate and Q10. Recommendations and perspectives The sensitivity of soil respiration rate to temperature change directly affect the estimation of carbon cycling and carbon accumulation, and predict the carbon balance and global warming degree of the terrestrial ecosystem in the future. Therefore, the study provides a theoretical basis for the improvement of soil productivity and the reduction of greenhouse gas emissions, recovery and improvement of the ecological environment in the loess region.
Keywords: carbon and phosphorus addition; soil respiration; temperature sensitivity; microbial biomass