Effects of Fertilization on Biological Properties of Rhizosphere Soil in Legume-Gramineae Mixtures in Hexi Corridor
In this study,'Gannong No.3'Medicago sativa and'Yuanye'Bromus inermis mixed grass-land were selected as the research objects,and five treatments were set up:no fertilization(N0P0K0),bal-anced fertilization(N2P2K2),no nitrogen application(N0P2K2),no phosphorus application(N2P0K2)and no potassium application(N2P2K0).The rhizosphere soil enzyme activity and microbial biomass car-bon,nitrogen,and phosphorus content were measured,and correlation analysis and grey correlation analy-sis were conducted to select the optimal fertilization mode for legume-grass mixture,in order to provide guidance for fertilization and management of mixed grassland in the Hexi Corridor from a biological perspec-tive.The results showed that compared with the N0P0K0 treatment,the activities of sucrase(SU),urease(UA),alkaline phosphatase(APA),catalase(CAT),microbial biomass carbon(SMBC),microbial bio-mass nitrogen(SMBN)and microbial biomass phosphorus(SMBP)were increased by 14.3%-64.1%,15.1%-62.0%,14.9%-73.2%,9.4%-39.8%,17.6%-113.1%,22.9%-91.7%,20.1%-74.9%,respectively.Among the different treatments,SU,APA,CAT activity,the content SMBC and SMBP were as follows:N2P2K2>N2P2K0>N0P2K2>N2P0K2>N0P0K0.The UA activity and SMBN con-tent were as follow:N2P2K2>N2P2K0>N2P0K2>N0P2K2>N0P0K0,and measured indexes under the four fertilization treatments were significantly higher than those under the N0P0K0 treatment.In different months,the activities of SU,UA,APA,CAT and the contents of SMBC,SMBN and SMBP in the rhizo-sphere soil of alfalfa and Bromus inermis were in July>May>October.Correlation analysis showed that the activities of the four enzymes were positively correlated with microbial biomass carbon,nitrogen,and phosphorus.The comprehensive evaluation of grey correlation degree showed that the effects of fertiliza-tion on the rhizosphere soil biological characteristics of'Gannong No.3'Medicago sativa and'Yuanye'Bromus inermis mixed grassland in Hexi Corridor were as follows:N2P2K2>N2P2K0>N0P2K2>N2P0K2>N0P0K0.
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