Effects of long-term fertilization on biodiversity and enzyme activity in grey desert soil

Long-term field experiments were conducted to examine the effects of long-term fertilization on biodiversity,enzyme activity,and ecological environment of grey desert soil,The obtained results are summarized as follows.(1)Fertilization had a significant effect on the number and community of soil animals.Long-term application of chemical fertilizers considerably affected soil animal Simpson index.Chemical fertilizer in combination with organic fertilizer increased soil animal diversity.Chemical fertilizer plus straw increased the abundance of soil animals,especially neanuridae and isotomidae,which increased in number by approximately 10 times.Animal uniformity was higher,but preponderant community was smaller in the long-term control plot(withoutfertilization).(2)Bacteria were thedominant community of microorganisms in the grey desert soil,whereas zotobacter and ammonifying bacteria dominated the special microbial physiological communities.Long-term application of chemical fertilizers alone inhibited the growth of soil microorganisms,as evidenced by the decreased number of several microbes.Chemical fertilizer with organic material increased soil microbial biomassby 15%-44%,as compared with the control.The number of microorganisms in control plot was greater than that of chemical fertilizer treatment plot.(3) Catalase activity was higher in grey desert soil,and that of invertase was relatively low.Available nutrient contents in the soil showed a negative relationship with catalase activity,but positively correlated with activities of the other three enzymes.Long-term applicaiton of chemical fertilizer alone reduced urease and invertase activity in the soil.Urease and phosphatase activities in the control plot were higher than that of chemical fertilizer only treatment.When chemical fertilizer was applied together with organic material,the activities ofurease,inverase,and phosphatase increased by 24%-31%as compared to the control.Therefore,chemical fertilizer in combination with organic material should be recommended for improving biodiversity,enzyme activities and subsequent soil quality of the desert soil.