Effects of water and nitrogen synergies on soil nitrogen content and enzyme activity of maize silage in Hexi Corridor
The effects of water and nitrogen synergy on soil nitrogen component content and related enzyme activities of silage maize in Hexi Corridor were investigated,and the relationship between soil nitrogen component content and related enzyme activities was studied.In 2022 and 2023,two kinds of drip irrigation(5535,6150 m3/hm2),recording as W1 and W2,and three nitrogen application levels(249,280,311 kg/hm2),recording as N1,N2 and N3,were conducted,with silage maize as the research object.The variation characteristics of total nitrogen(TN),ammonium nitrogen(NH4+-N),nitrate nitrogen(NO3--N)and microbial biomass nitrogen(MBN)under different water and nitrogen synergistic treatments were analyzed,as well as the correlation with urease(URE),protease(PRO),alkaline phosphatase(ALP)and catalase(CAT)activities.The results showed that:(1)The content of nitrogen components and related enzyme activities decreased with the increase of soil depth.(2)Compared with traditional drip irrigation,water-saving drip irrigation significantly increased the contents of TN,NH4+-N,NO3--N,MBN and the activities of URE,PRO,ALP and CAT in silage maize soil.With the increase of nitrogen application rate,the contents of TN and MBN in soil increased,the activities of URE and PRO also increased,while the contents of NH4+-N,NO3--N and the activities of ALP and CAT increased first and then decreased.(3)In 2022 and 2023,except for W1N3 treatment,the yield of silage maize under W1N2 treatment was significantly(P<0.05)higher than that of other treatments by 5.76%-24.78%and 9.26%-37.35%,respectively,but the yield difference between W1N2 and W1N3 treatments was not significant.(4)TN was extremely significantly(P<0.01)or significantly(P<0.05)positively correlated with URE,PRO and CAT.NH4+-N and NO3--N were extremely significantly positively correlated with URE,PRO and CAT(P<0.01),and significantly positively correlated with ALP(P<0.05).MBN was significantly positively correlated with URE(P<0.05).There were extremely significent(P<0.01)or significant(P<0.05)positive correlations between soil nitrogen fractions,enzyme activities and yield.In summary,the drip irrigation and nitrogen application rates of 5535 m3/hm2 and 280 kg/hm2 were the ideal water and nitrogen synergistic mode,which could significantly improve the soil nitrogen content and related enzyme activities of silage maize in Hexi Corridor.
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