Effects Of Addition Of Both Maize Stalk And Its Biochar To Greenhouse Gas Emissions And N Transformations Of Loess Soil

In recent years, the greenhouse gas emissions become a hot point in the Global issue ofclimate change. Stalk and nitrogen were applied widely in the arid as the main method ofincrease crop production, but a large number stalk applied may affects soil denitrification,increases soil CO2and N2O emissions. Therefore, the researchers focused on biocharproduced by stalk, Biochar has stable structural, it can not only fix organic carbon andnutrient in soil, and also can improve the soil fertility, soil physical and chemical properties.However, effects of biochar addition on greenhouse gas emissions are controversial. Thisstudy investigates the impacts of soil water content, organic carbon (maize stalk, biochar) andnitrogen on the greenhouse gas (CO2and N2O) emissions and N transformations, usinglaboratory incubation experiment (28℃) via quadratic rotational combination design. Theresults are following:1) When applying stalk to the soil, CO2and N2O emissions were mainly affected byorganic carbon, followed by water and nitrogen; in contrast, when biochar adding, the CO2emission was mainly affected by water, followed by organic carbon and nitrogen, however,the N2O emission was mainly affected by organic carbon, followed by nitrogen and water.2) For the interactions among three factors, when stalk was applied, the orders ofcontribution on CO2emission is carbon and nitrogen> water and nitrogen> water andorganic carbon, however, when biochar was applied, the orders is water and nitrogen=waterand carbon> carbon and nitrogen. In contrast, the orders of contribution on N2O emission iswater and carbon> carbon and nitrogen> water and nitrogen when stalk was applied,however, the orders of factors contribution is water and nitrogen> carbon and nitrogen>water and carbon when biochar was applied.3) The optimal combination for the lowest cumulative emissions of CO2for maize stalkapplication was considered as a combination of30%water content, no stalk applied and the81.9mg·kg-1nitrogen. For biochar application derived from maize stalk, the optimumcombination was a combination of10%water content, no biochar applied and48.4mg·kg-1nitrogen. As for N2O emissions, a combination of30%water content, no stalk amendmentand100mg·kg-1nitrogen was the better condition when the maize stalk was amended. Incontrast, when biochar used, the best condition was a combination of10%water content, nobiochar added and100mg·kg-1nitrogen. In summary, compared to stalk, the biochar can effectively reduce soil emissions of greenhouse gases.4) In the soil applied with corn stalk, net nitrogen mineralization was influenced mainlyby content of organic carbon, and then by contents of water and nitrogen, but in the soilapplied with biochar, it was mainly by content of nitrogen and then by contents of water andorganic carbon. The difference between the two carbon sources in effect on net Nmineralization was extremely significant (p <0.01). Compared with maize straw, biocharincreased soil NO3--N and NH4+-N concentrations, and significantly decreased N2O emission.In the soil applied with biochar, the concentration of inorganic nitrogen changed slowlyduring the entire incubation period, while in the soil applied with corn stalk, it did drasticallyin the first two weeks of the incubation. Hence, it is obvious that application of biochar isconducive to reduction of emission of the greenhouse gas, N2O.5）Stalk and biochar addition has significant effect on the soil pH in a short period, buthad no significant influence for a long time. Applying stalk and biochar can improve soil CEC,and especially biochar can make soil CEC stabilize at a higher value.