Effects Of Biogas Slurry Irrigation On Soil Nitrogen Leaching And Nitrifying Bacteria

Biogas slurry is an agricultural waste resource,because it is rich in nutrients and is often used as fertilizer to apply to the soil.However,the excessively high NH₄⁺-N content of the biogas slurry causes the soil nitrification intensity to increase,resulting in increase d NO₃^--N content in the leaching water,and there is a risk of NO₃^--N pollution.As we al l know,irrigating soil with biogas slurry as a nitrogen source is one of the important fact ors affecting soil microbial activity,and nitrifying bacteria are the main bearers of soil nit rification.There is a direct relationship between nitrifying bacteria,soil nitrification,and s oil nitrogen leaching.It is proved that the effect of nitrogen application intensity by bioga s slurry irrigation on nitrifying bacteria,soil nitrification,and soil nitrogen leaching is of great significance to environmental pollution control.Using the yellow soil and Calcareous soil of typical arable land in Guizhou as resear ch materials,the effects of the application of biogas slurry on indoor soil nitrogen leachin g and nitrifying bacteria were explored through indoor simulated biogas slurry test.Nitrog en leaching test biogas slurry irrigation uses 6 nitrogen application intensity 0 kg N/hm²?24 kg N/hm²?72 kg N/hm²?120 kg N/hm²?168 kg N/hm²?240 kg N/hm².The results s how that:?1?Yellow soil leaching water TN,NH₄⁺-N,NO₃^--N all increase with the increa se of nitrogen application intensity of biogas slurry,and the risk of nitrogen leaching is m uch higher than that of Calcareous soil.?2?The species diversity of Calcareous soil is mo re susceptible to biogas slurry irrigation.?3?The sequence numbers of s??unclassified?g??Nitrosospira and s??unclassified?g??Nitrospira increase with the intensity of nitrogen applic ation by biogas slurry irrigation,which is the reason for the increased nitrification intensit y of yellow soil and Calcareous soil.In the static culture test,the biogas slurry was added with 4 nitrogen application inte nsities,namely 0 kg N/hm²,72 kg N/hm²,120 kg N/hm²,and 168 kg N/hm².The results show that:?1?12-week biogas slurry culture increases the SOC and TN of yellow soil a nd Calcareous soil,while the yellow soil and Calcareous soil TN are not affected by the addition of biogas slurry within 1 week.?2?After 12 weeks of cultivation,NH₄⁺-N in yell ow soil and Calcareous soil decreased,NO₃^--N increased,and nitrogen flux during nitrifica tion increased.?3?Cultivation to 12 weeks does not affect the alpha diversity of yellow s oil colonies but increases the alpha diversity of lime soil colonies.?4?The beta diversity of yellow soil species cultivated to 12 weeks is more susceptible to the addition of biogas slurry.?5?Under static cultivation conditions,the conclusion that the increase of nitrifyin g bacteria by biogas slurry leads to an increase in soil nitrification intensity is consistent with the nitrogen leaching test.The research results provide a reference for the mechanism of NO₃^--N non-point source pollution caused by biogas slurry irrigation.