Study On Soil Improvement Characteristics Of Pig Waste Hydrochar

Hydrochar is a method that can directly prepare wet biochar.Compared with pyrolytic carbon,the hydrochar has a better nutrient balance,but different hydrochar materials have different effects on soil and plants.Therefore,specific analysis is still needed.The hydrochar was prepared by pig waste under180? and 1h carbonization conditions,passed 80-day soil culture test,60-day soil mineralization test,germination test and two consecutive rounds of potting test in order to evaluate the soil improvement characteristics of hydrochar,this research studied the effects of different amounts of pig manure hydrothermal carbon on soil physical and chemical properties,organic carbon mineralization and plant growth.The main results are as follows:(1)During soil cultivation,the soil p H decreased from 7.17 to 6.67-6.98 during the cultivation process,and the overall change trend was first decreased and then increased.The content of soil available nitrogen and available phosphorus dropped to a minimum on the 10 th and 15 th days and then rise up.Soil electrical conductivity and nutrient composition increased with the addition of hydrochar.When the addition amount was 4%,the soil electrical conductivity,total organic carbon,water-soluble organic carbon,available nitrogen,available phosphorus and available potassium content increased by 58.9%,54.3%,146.4%,27.4%,591.2% and 88.6%,respectively.(2)The rate of soil mineralization,the potential of soil mineralization and the turnover rate of soil organic carbon were increased by pig waste hydrochar.When the addition amount was 4%,the cumulative mineralization amount of soil increased by 152%.(3)The single used pig waste hydrochar and mixed with quartz sand showed plant toxicity,and the higher the application rate,the greater the inhibition effect.However,in the soil environment,pig waste hydrochar showed hormesis effect on the seeds of Brassica oleracea.When the addition amount was1.5%,the germination rate increased by 8.33%.(4)The contents of total organic carbon,water soluble organic carbon,total nitrogen,total phosphorus,available N,P,K and electrical conductivity of soil were increased in different degrees except for total K content.And the results of the second-cut were particularly significant.When the addition amount was 4%,the contents of soil electrical conductivity,total organic carbon,water-soluble organic carbon,total nitrogen,total phosphorus,available nitrogen,available phosphorus and available potassium increased by 51.44%,29.67%,118.61%,29.49%,76.35%,75.01%,369.14% and 93.99%,respectively.The p H value of soil decreased from 7.18 to 6.75-7.05 during the cultivation process,showing an overall upward trend.In the first-cut,low concentration of pig waste hydrochar produced hormesis effect on the yield and growth traits of Brassica oleracea,but in the second-cut,it promoted the growth of Brassica chinensis.When the application rate was 1.8%,the yield,aboveground dry weight,underground dry weight,plant height and leaf area of Brassica oleracea increased by 147.16%,184.08%,198.83%,respectively 24.20% and 85.32%,respectively.To sum up,1.8% of the addition is the more suitable amount of pig waste hydrochar as soil amendment.