关键词: 沼液；过量还田；土壤；玉米；环境质量；产量, 品质；安全容量

Abstract: The effects of different amounts of biogas slurry application on soil environmental quality and maize growth were studied,and the safe capacity of biogas slurry returning to the field was put forward.Five treatments were used, and application amount of biogas slurry was converted by maize nitrogen nutrient requirement. The five treatments included no fertilizer application(0 t/ha of N,CK),one time nitrogen equivalent biogas slurry(0.885 t/ha of N ,1N),two times nitrogen equivalent biogas slurry (1.770 t/ha of N,2N),three times nitrogen equivalent biogas slurry(2.655 t/ha of N,3N),four times nitrogen equivalent biogas slurry (3.540 t/ha of N,4N).The results showed that,the content of Cu and Zn in soil could be significantly increased when biogas slurry was returned to the soil,and 1N treatment was the best safe capacity for soil environment. Cu and Zn pollution risk existed in 2N,3N,and 4N treatments,among them,the contents of Cu and Zn in 4N treatment at the mature stage exceeded their risk screening values by 10.96% and 10.36%,reaching the highest risk. Compared with CK,the soluble salt content and the pH values of soil increased at maize seedling stage,but they showed a decreasing trend with the extension of maize growth period. At the mature stage of maize,the soil soluble salt contents of 1N,2N,3N and 4N treatments were 30.59%,52.16%,72.35% and 108.63% higher than that of CK,and the soil pH values were 3.95%,6.41%,9.05% and 13.65% higher than that of CK.The mortality of ascaris eggs in all treatments was 100%,so there was no safety risk of the survival of ascaris eggs when biogas slurry was applicated into soil, but 3N and 4N treatments had risk of Escherichia coli contamination.The quantities of Escherichia coli in the two treatments were 20 and 30 per gram soil respectively at the mature stage.The biogas slurry application could increase the maize yield,and improve the maize quality significantly,and 3N treatment was the best,compared with CK,the contents of crude protein,crude fat and crude starch increased by 19.82%,89.01% and 11.31% respectively,and the yield was 2.08 times of CK.It was concluded that 3N treatment was the best when the yield and quality were taken as the priority objectives,and 1N treatment was the best when the soil environmental safety capacity was taken as the priority goal.

Key words: Biogas slurry, Excessive returning, Soil, Maize, Environmental quality, Yield, Quality;Security capacity