Effects Of Carbon And Nitrogen Additions On The Mineralization Of Soil Carbon, Nitrogen, And Nitrogen Transformation Rate Of Alpine Meadow In Northern Tibet

The degeneration of Stipa purpurea-Kobresia humilis Meadow lead to reduced grassland vegetation productivity and the fuction of ecological barrier as fixed surface on grassland vegetation was lost, in Northern Tibet. And cause loss of ecological barrier function about fixed topsoil of grassland vegetation, bring some problems such as soil erosion and desertification. And there is still controversy about restoration applications of large areas natural grassland that fertilizer as a means to supplement soil nutrient, restore grassland productivity and ecological barrier function.The research work take underground carbon pool, nitrogen Library of alpine meadow as the research object to carry out the following two experimental research sections:Firstly, Conducting quantitative research that impact on the soil carbon and nitrogen mineralization of different management models in the Northern Alpine meadow by adding carbon, nitrogen and plant litter.Secondly, researching that impact on soil nitrogen transformation rates by sucrose (0,120,600kg C·ha-1) and K1SNO3or (NH4)2SO4additions. The main conclusions are as follows:1After56d situ culture, we found the cumulative amount of soil organic carbon mineralization, the average mineralization rate to foster early0-3d most concentrated. Soil respiration CO2-C cumulative release not only be related to the amount of sugar added, but also to the carbon, nitrogen and total soil C after adding plant residues composed is about C/N value, dosage soil respiration600kg C·ha-1of cumulative release of CO2-C greater than120kg C·ha-1and do not add C. C/N value is closer to25, the greater accumulation of soil respiration CO2-C emissions.2600kg C·hm-2were added to soil which can quickly increase soil respiration CO2-C emissions. In the initial experiment (3d), it can rapidly improve the release rate of CO2-C. after28d later, it be stabilized or decreased. The impact to net nitrogen mineralization, net mineralization rate, MBC, MBN, DOC and DON occured in the first7d, Section7d, the first28d, the first7d, the first28d and56d, and continued until the end of the test, it is role to reduce the net mineralization were net nitrogen mineralization rate and increase the MBC, MBN, DOC and DON content.3100kg N·hm-2addition to soil can increase nitrogen mineralization in a longer duration, the main role is to increase the net nitrogen mineralization and net mineralization rate,MBC, DOC and DON content, while reducing the MBN content.4Carbon, nitrogen, plants and management work together to add the impact of soil respiration to release CO2-C accumulation, net nitrogen mineralization, net mineralization rate, MBC, MBN, DOC and DON, etc., and it has a certain stage.515NO3-dilution technique for total nitrification study found that nitrogen, when without carbon, the growing season of July, August and September gross nitrification rates were5.77mg N·kg-1(dry soil)·d-1,4.98mg N·kg-1(dry soil)·d-1,6.33mg N·kg-1(dry soil)·d-1; while the C concentration of600kg C·ha-1,when total soil nitrification rates were increased by21.66%,30.72%,2.84%from July to September.