Effects of soil amendments on nitrogen cycling functional genes'abundance,extracellular enzymes and soil fertility index in a sandy fluvo-aquic soil
A four-year(2015-2019)field experiment was carried out under wheat-maize rotation system in Langfang city,Hebei province.The purpose of the experiment was to study how inorganic and organic amendments affecting nitrogen cycling functional genes'abundance and extracellular enzymes.The experiment consisted of four treatments:control(CK),inorganic amendment(SA),organic amendment(SC),and organic+inorganic amendments(SCA).After maize were harvested in 2019,soil samples were collected from arable layer.Chemical properties,abundance of nitrogen cycling functional genes,and extracellular enzyme activities were measured.Soil integrated fertility index(IFI)was calculated using factor analysis method and Nemero index method.The results showed that amendments significantly increased the absolute abundance of soil nitrogen fixation genes(nifH),ammonia oxidizing bacteria genes(AOB-amoA),and denitrification genes(nirS and nosZ)(P＜0.05).The abundance of functional genes was in the order of SCA＞SC＞SA.The redundancy analysis(RDA)showed that soil organic carbon was the key factor affecting functional gene abundance.Furthermore,organic amendments significantly improved carbon(β-Glucosidase,β-Cellobiohydrolase),nitrogen(β-1,4-N-acetylglucosaminidase,leucine aminopeptidase)and phosphorus(alkaline phosphatase)related enzyme activities(P＜0.05).RDA results showed that available phosphorus was the main factor affecting enzyme activities under different amendments.Soil IFIs using factor analysis method and Nemero index method were both positively correlated with maize yield.In conclusion,combined application of organic and inorganic amendments could increase the abundance of functional genes related to nitrogen cycling,and the activities of extracellular enzymes related to carbon,nitrogen and phosphorus cycles,and improve the soil IFI.Therefore,combined application of organic and inorganic amendments is an important strategy to promote nutrient condition and crop yield in sandy soil.
organic amendmentattapulgitefunctional geneextracellular enzymeNemero index
万方数据
维普
