Impacts of Simulated Warming and Nitrogen Deposition to Coupling Effect between Soil Nitrogen and Phosphorus in Songnen Grassland
|School||Northeast Normal University|
|Keywords||Coupling effect Soil nutrient Soil nitrogen Soil phosphorus Warming Nitrogen application|
With the increasing global change,people pay attention to the impact which it brings to the soil layer and the nutrients. The research was finished in Leymus chinensis (Trin.) Tzvel. grassland in Songnen plain. We simulated nitrogen application by adding ammonium nitrate. We simulated warming by Infrared Radiator. After three years of field and indoor experiments, we complete the research of the soil nitrogen, phosphorus and other nutrients as well as the coupling effect between nitrogen and phosphorus.From 2007 to 2009, we manipulated three treatments: warming, nirogen application and warming plus nitrogen application. Treatments made soil nutrients changed, nitrogen application treatment significantly increased the content of total nitrogen and available nitrogen, nitrogen application stimulated the release of the soil’s own available nitrogen, warming plus nitrogen application significantly increased the content of the available nitrogen, there was interaction between warming and nitrogen application treatment. Three treatments made the soil net nitrogen mineralization rate increased to varying degrees.Nitrogen application significantly decreased the content of total phosphorus and available phosphorus, which might because of stimulating the phosphorus absorption of plant by adding nitrogen, or soil microbial immobilization reduced the content of phosphorus,but warming and warming plus nitrogen application treatments had no significant affection. Comparing with the ambient, three treatments had no significant impact to the content of organic carbon, but the seasonal variation showed that the content increased first then decreased, reached its peak in August, nitrogen application and warming plus nitrogen application treatments increased the content of organic carbon.The correlation analysis showed that the content of soil available nitrogen significantly positively linear correlated with the content of organic carbon and soil temperature. Soil net nitrogen mineralization significantly positively linear correlated with the content of available nitrogen and the soil temperature. Warming or nitrogen application treatment, the content of available nitrogen significantly positively linear correlated with the content of total phosphorus, there was coupling effect between the two elements. Warming and nitrogen application treatment, the content of total nitrogen significantly positively linear correlated with the content of available phosphorus, there was also coupling effect between these two elements.