Effect Of Concentrated Biogas Slurry Fertilizer On Crop Yield And Quality And Soil Quality

With the development of livestock and poultry farming and biogas projects,the discharge of biogas slurry is increasing day by day.The biogas slurry is rich in nitrogen,phosphate,potassium and other nutrients,which can be used as fertilizer in farmland.However,the contradiction between the continuous discharge of biogas slurry and the seasonal fertilizer requirement of farmland,the low concentration of nutrient components in biogas slurry,the difficulty in transportation and storage,and the difficulty in commercialization are the dilemmas facing the utilization of biogas slurry fertilizer.In order to solve these difficulties,biogas slurry is concentrated by membrane concentration technology and reformulated according to the standard of water-soluble fertilizer to obtain concentrated biogas slurry fertilizer,which is convenient for storage,transportation and application.In order to study the effects of concentrated biogas slurry fertilizer on crops and soil,we independently prepared concentrated biogas slurry fertilizer,and by using pot experiment,set up three different fertilizer treatments(two kinds of water soluble fertilizer and concentrated biogas slurry fertilizer)and three different fertilization gradient.The effects of self-made concentrated biogas slurry fertilizer on Chinese cabbage growth,nutrient and heavy metal absorption,as well as nutrient,heavy metal and antibiotic contents in soil were studied through comparison,and the following results were obtained:(1)For the biological characteristics of Chinese cabbage plants,the plant height and fresh weight per plant of the self-made concentrated biogas slurry were increased in the two seasons compared with the two water-soluble fertilizer treatments,increased by 0.88%~15.67% and 0.44%~71.01% respectively;compared with the control treatment,the dry matter quality of the three fertilization treatments increased,and the increase of the self-made concentrated biogas slurry fertilizer was the most obvious.With the increase of fertilization amount,the plant height,fresh weight and dry matter quality of the plants increased first and then decreased,and reached the maximum when the nitrogen application rate was 0.1 g/kg.(2)For the nutrient and nitrogen utilization rate of Chinese cabbage plants,in the two cropping seasons,compared with the two water soluble fertilizers,the total nitrogen increased by 0.47%~15.44% and total phosphorus increased by 9.54%~34.46% in the plants treated with concentrated biogas slurry fertilizer under the same amount of fertilizer,and the total potassium increased but did not reach the significant level.The absorption efficiency and agronomic efficiency of the self-made concentrated biogas slurry fertilizer were higher than those of the two water-soluble fertilizers.For different fertilizer treatments,the total nitrogen,total phosphorus and total potassium of Chinese cabbage increased first and then decreased with the increase of fertilizer amount,and the nitrogen utilization rate decreased with the increase of fertilizer amount.(3)For soil nutrient content,fertilization reduced the soil p H value in the two cropping seasons.Compared with the control treatment,the p H of commercially available water-soluble fertilizers decreased by 4.18%~11.88%,and the self-made water-soluble fertilizers decreased by 3.17%~8.43%,and the self-made concentrated biogas slurry fertilizers decreased by 1.77%~6.77%.Compared with the two kinds of water soluble fertilizers,the self-made concentrated biogas slurry fertilizer can increase the content of organic matter and total nitrogen in soil,but the continuous planting for two seasons will reduce the overall content.The self-made concentrated biogas slurry fertilizer can improve the available nutrients in soil(Alkali-hydrolyzed nitrogen,available phosphorus and available potassium),improve the ability of soil to provide nutrients,and the increase is more obvious in two consecutive planting seasons.For the treatment with different amount of fertilizer,the organic matter,total nitrogen and available nutrients of the soil would increase with the increase of the amount of fertilizer.(4)For the heavy metal content in Chinese cabbage plants and soil,the self-made concentrated biogas slurry fertilizer increased the content of heavy metal Zn,Cr and As slightly,while the content of Cu and Ni was relatively stable.The contents of heavy metals Zn,Cu,Cr,Ni and As in the soil were higher than those of the two water-soluble fertilizers and the control,but did not reach a significant level.(5)For the content of antibiotics in the soil,the antibiotic content of the maximum fertilization amount in the two consecutive seasons was not detected.In summary,the test results show that for the yield and quality of crops,the application of self-made concentrated bio-liquid fertilizer can improve the plant height,fresh weight and dry matter quality of Chinese cabbage,promote the absorption of nutrients by crop plants,and improve the utilization rate of nitrogen fertilizer.And it will not cause the risk of heavy metals exceeding the standard.For soil quality,concentrated biogas slurry fertilizer can slow down the acidification of soil and increase soil organic matter and nutrient content;and the application of concentrated biogas slurry fertilizer will not cause soil heavy metal super and antibiotic hazard.