Effects Of Straw Biochar On Carbon Pool In Mollisol

Located in the middle of Songnen Plain, Heilongjiang province is a big province of grain in China and its soil is black. However, as people on the black soil of excessive reclamation and utilization recently, resulted in serious soil quality declining, at the same time, the rich crop straw resource in Heilongjiang Province brings many serious burning straw problems. How to improve the quality of black soil, use straw resource ecologically became an important issue of research.As a good soil amendment, on one side biochar increase the soil fertility, it is good to reduce the amount of greenhouse gas on another side, which provide new ideas to the protection of black soil. But the influence mechanism of adding biochar on soil organic carbon pool is still not clear.This study was at the greenhouse experimental base of Northeast Agricultural University. It was a pot experiment which the test crop was soybean, and 10 treatment in total. In this study, biochar feedstock type were in difference(including corn straw, wheat straw and rice straw) as experiment materials and they were designed to different application level, the quality proportion of biochar and soil was designed by 1%, 5%, 10%.Take rhizosphere soil of soybean at its seedling stage, florescence, podding stage, filling stage and mature stage for experients. Looking into the impact of biochar on soil carbon pool related groups and carbon pool management index aims to reveal the mechanism about influence of biochar on soil carbon pool, in addition, it also wil lays a scientific foundation. The main results are as follows:(1)Adding biochar to soil increased soil organic matter content in some extent. The addition of straw to the organic matter also improved. Compared to the control, high amount(10% by mass ratio) and medium amount(5% mass ratio) biochar treatment significantly led to an increase at soybean different growth stages in rhizosphere soil organic matter content(P<0.05). Among them, the medium amount carbon treatment significantly increased soil organic matter content of 32.5%, high amount carbon treatment significantly increased it of 38.1%. The impact of same amount but different source of biochar on soil organic matter shows that when it is added to soil with low amount, the effects of biochar on organic matter contents has little relationship with feedstock type.(2)The effects of adding biochar to soil on active organic matter content has little to do with feedstock type at later growth stage of soybean(including podding stage and filling stage and mature stage).High biochar application rate added significantly promoted the active soil organic matter content(P<0.05). The impact high biochar application rate biochar on soil organic matter shows that it increased soil active organic matter content of 1.35mg/g to 1.59mg/g(average 1.45mg/g).(3)Increasing biochar application rate led to an increase in the soil microbial biomass carbon content. The carbon content of soil microbial biomass increased from 16.7% to 85.6%, but its effect on microbial biomass carbon content was closely related to soybean growth period, and it had little relation with biochar application rate. The impact of same amount but different source of biochar on soil microbial biomass carbon content shows that biochar feedstock type showed no increase in it.(4)Biochar significantly promoted soil light fraction organic matter content and soybean rhizosphere soil light fraction organic matter content increased with the amount of biochar application. Impact of same amount but different sources of biochar on light fraction organic matter varide slightly due to growth period in deference but it had no significant correlation with biochar feedstock type. Thus the change of light fraction organic matter did not had relationship with biochar feedstock type.(5)Biochar is beneficial to soil carbon management. The impact of low amount(1% mass ratio),medium amount biochar(5% mass ratio) on soil carbon pool index change with soybean growth period, and compared to corn and rice biochar, high amount wheat biochar(10% mass ratio) biogenic carbon is more greatly improve the carbon pool management index(P<0.05), wheat biogenic carbon compared with maize and rice biogenic carbon carbon pool management index significantly improve 60.1%, 36.6%.(6)Effect of carbon on the CO2 emissions during the mineralization of the soil was related to the culture time. The amount of CO2 emission was significantly increased in 20 days, compared with the control, it increased from 78.6% to 80.1%(p<0.05).However, according to the different levels of corn biochar, the amount of CO2 emissions decreased with the extension of the incubation time, and adding biochar to soil had little to do with soil CO2 respiration in a short-term.