Dynamic Change Of Carbon, Nitrogen And Nutrients Under The Condition Of Simulated Climate Change In Paddy Soil

The dramatic climate change in recent centuries is closely related to human productive activities (including industrial and agricultural activities) and new life style. As most research found, the increasing higher CO2 concentration has made the world significantly warmer. Much more invisible changes had been detected in the last century, and this kind of influence will give more challenge in a long future time. Little changes in climate on temperature, precipitation, extreme weather disasters and/or soil condition may produce uncertainties on food security and society stability.. There have many reports published about the effect of elevated CO2 concentration or warming conditions on terrestrial ecosystem, especially on agro-ecosystem. However, few researches focused on both elevated CO2 concentration and warming conditions. In our study, the experiment was carried out with a simulated climate change in Guli town, Changshu city, Jiangsu Province since 2009. Paddy soil had been collected according to the four rice growth stages, aiming to make a deeper understanding of how soil available nutrients, soil carbon and nitrogen changes during the rice growth stage. Four treatments was designed as ambient(CK), elevated atmospheric CO2 concentration to 500ppmv(CE), elevated atmospheric CO2 concentration to 500ppmv and 1.5 degree Celsius warmer(CW) and just 1.5 degree Celsius warmer(WA), three duplicates for each treatment. The main results showed as listed below:(1) Rice yield declined under warmer canopy temperature, while the elevated CO2 concentration promoted the aerial part biomass.(2) The soil ammonium nitrogen reduced under CW in jointing stage while the soil nitrate nitrogen on the contrary. The soil available phosphorus decreased under both treatments of CW and WA, soil readily available potassium under CE treatment also decreased compared to the other treatments. Further more, soil potassium dropped at tillering stage under treatments of CW and WA.(3) The content of soil water dissolved organic carbon(WDOC) before ripening stage decreased pretty much under CW treatment, while the soil organic carbon(SOC) and microbial biomass carbon(MBC) increased in all four stages. Soil total nitrogen in tillering stage and ripening stage increased under CE and CW treatments.In conclusion, the effects of simulated global warming on soil readily available nutrients varied in different growth stages. Besides these measured individual nutrients showed distinctive change in the same stage. These results could not confirmed that the influence of elevated atmospheric CO2 and temperature simply stimulated the soil nutrients activity nor just antagonism. The thorough influence could be much more complex with the links of soil microbial activities, soil moisture condition and plants’specific response, which means that much more work need to be done for the clear-cut mechanism of how climate change influences on the dynamic variation of soil carbon, nitrogen and nutrients.