含硫化合物对不同土壤硝化作用和N2O排放的影响

Effects of Sulfur Compounds on Soil Nitrification and N2O Emission in Different Soils

研究发现,甲硫氨基酸对土壤氮的影响有别于其他氨基酸,为了探究这种影响差异是否与含硫有关,以3种不同pH值土壤:东北黑土(D)、福建红壤(F)、河南碱性土壤(H)为研究对象,设置对照(CK,0 mg·N·kg^-1)、添加甲硫氨基酸(Met,40 mg·N·kg^-1)、半胱氨酸(Cys,40 mg·N·kg^-1)、硫酸钠(S,91 mg·S·kg^-1)4个处理在室内培养21天,分析各土壤的硝化过程和N2O排放。结果表明:与CK相比,Met和Cys处理的净氨化速率在土壤D和F显著升高,在H土壤中为负值,S处理变化不明显;Met和Cys处理显著提高了H土壤净硝化速率403.6%和312.0%,显著降低了F土壤146.4%和122.4%,而在S处理变化不明显。可见含硫氨基酸添加促进酸性土壤氨化、抑制硝化作用,但对碱性土壤影响相反。在CK和S处理中,土壤净硝化速率表现为D>F>H,而在Met和Cys中则表现为H>D>F,有机硫和无机硫影响不同,在有机硫化合物处理中,净氨化速率和净硝化速率分别与土壤pH值呈负相关和正相关关系。然而在无机硫化合物处理中,净氨化速率与土壤pH值呈正相关关系,pH对净硝化速率没有影响。Met和Cys处理的N2O产生速率显著升高,S处理与CK差异不明显,说明有机含硫化合物促进了N2O的释放,尤其是F土壤。由于N2O是硝化作用的产物,因此,F土壤硝态氮降低可能与硝态氮保持有关,并不是限制了硝化。

Studies have found that the effect of methyl sulphate on soil nitrogen is different from other amino acids. In order to explore which is related to sulfur, three soils with different pH values, Northeast Black Soil(D),Fujian Red Soil(F),Henan Alkaline Soil(H)were selected for incubation for 21 days under control(CK,0 mg·N·kg^-1)and addition of methionine(Met,40 mg·N·kg^-1),cysteine(Cys,40 mg·N·kg^-1),sodium sulfate(S,91 mg·S·kg^-1). During experiment,the nitrification process and N2O emissions of each soil were analyzed. The results showed that compared with CK,the net ammonification rates at Met and Cys treatment were significantly increased in soil D and F,and negative in H soil,but that at S treatment was not obvious. Met and Cys treatment significantly increased net nitrification rate was by 403.6% and 312.0% in H soil,significantly reduced by 146.4% and 122.4% in F soil,but there was no effect of S treatment. These results indicated that the addition of sulfur-containing amino acids promotes ammonification and inhibits nitrification in acid soil,but the opposite effect was found in alkaline soil. In the CK and S treatments,the net nitrification rate of the soil is D>F>H,while it was H>D>F in Met and Cys. The influence of organic sulfur and inorganic sulfur on soil nitrogen was different. In the treatment of organic sulfur compounds addition,the net ammonification rate and net nitrification rate were negatively correlated and positively correlated with soil pH,respectively. However,in the treatment of inorganic sulfur compounds addition,the net ammonification rate is positively correlated with soil pH,which was no found for the net nitrification rate. The N2O production rate was significantly increased by Met and Cys treatment,but the significant difference between S treatment and CK was not observed,indicating that organic sulfur compounds promoted the release of N2O,especially in F soil. Since N2O production is in nitrification,the reduction of nitrate nitrogen in F soil may be related to nitrate nitrogen retention rather than limited nitrification.