不同有机物料对土壤N_2O排放的影响与调控

Influence and control of paper waste and plant residual on N_2O emission from soil

通过向土壤施加15N标记的莴笋残体(处理R)、废纸浆(处理P)及二者混合物(处理RP),并利用不同的压力使其成为3种不同容重处理的土壤样本,进行密闭培养,定时测定土壤N2O排放量及土壤溶液中NO3-与NH4+的动态变化,以探讨N_2O的产生与调控机制.结果表明,8d N2O释放量为R处理最大,RP处理其次,P处理最小.短期内(8d)R处理N2O释放最大量为空白对照(CK)的15倍,增加了土壤反硝化作用;P处理在同期内不能增加N2O释放量,证明这种废纸浆可少量(<2.5%)施用于农田中.RP与CK、P处理比较,可以刺激微生物活性和增加土壤反硝化作用;与R处理相比较,可以增加氮的固定.增加有机质的添加量使同一容重水平的RP处理N2O释放量高于R处理.70%的土壤样本随容重增加N2O释放量增加.土壤容重的增加同时影响了废纸浆的分解速率和土壤溶液中NO3-与NH4+浓度.

Farmland is an important resources of N2O emissions. In order to decrease greenhouse gases emission and loss of nitrogen in soil two experiments with added 15N labeled lettuce residuals(R), paper wastes(P), mixture of both(RP) and utilizing different pressure (2, 6, 16kg) were proceeded, then were incubated under content temperature and moisture for determining soil N2O emission, and dynamic change of NO3- and NH4+ in soil solution at various time to probe the production and control mechanism of N2O. The results of experiment I showed that N2O emissions in the first 8 days were as follows: R>RP>P=CK, the maximum N2O emission at the R treatments were 15 times higher than at CK treatments, and lettuce residuals increased denitrification in the soil; N2O emissions at the P treatments were not increased for the same period, which proved that small amounts of this kind of paper wastes (2.5%) could be used in farmland. Microorganism activity at the RP treatments could be simulated and soil denitrification increased, compared with the CK and P treatments. The results of experiment II showed that increasing addition amounts of organic matter (R: 2%, P: 6%, RP: 2%+6%) with the same bulk density level at the RP treatments, releasing N2O amounts were higher than at the R treatments. With increasing bulk densities the N_2O emissions in the 70% soil samples were increased. Increasing soil bulk density could affect the decomposition of paper wastes and the concentrations of NO3- and NH4+ in soil solution.