Study On Production Of Straw Biochar-based Biogas Slurry Fertilizers And Their Effects To 3 Kinds Of Pastures

In recent years,China's agriculture and livestock industry have been developing rapidly,so a large quantity of agricultural waste,livestock or poultry waste and crop stalks were produced.The past methods to treat these waste disposal has caused serious damages to environment and the sustainable development of agriculture.It has been proved that crop straw can be made into biochar mixed with other fertilizers to make the biochar-based fertilizers.This is a new way of waste recycling to improve soil physical and chemical properties,to increase soil nutrients and to improve crop yield and quality.However,most of the biochar-based fertilizer are mixed by biochar and other chemical fertilizers,such as urea,thus certain environmental risks exist.Furthermore,the application costs are too high.Therefore,the study of eco-friendly biochar-based fertilizers with,lower input but higher efficiency is required to promote the waste resource recycling and the sustainable development of agriculture and forestry.In this study,the granulated biochar-based fertilizer was made by mixing the biochar,which was made from com straw,with cow dung biogas slurry.Based on orthogonal experiment with five-factors(five factors:A:addition radio of biochar and biogas slurry;B:dip of disc of pelletizer;C:binder species;D the added amount of binder;E error term)and four-levels,the mechanical properties,granulation rate and nutrient release properties were compared among different fertilizers.Based on this,two kinds of optimal fertilizers(self-made biochar-based fertilizerl and ?)were selected.The pasture species of Elymus sibiricus L.,Medicago sativa L.and Poa pratensis L.were planted in pots to study the effects on growth and physiological indexes of plants by different biochar-based fertilizers,through an orthogonal experiment with four-factors(A:biochar-based fertilizer type;B:plant species;C:add amount of fertilizers;D:error term)and three-levels.The effect of biochar-based fertilizers was evaluated by the range analysis of individual indicators,analysis of variance and a comprehensive analysis of a number of indicators such as orthogonal experiment analysis.The conclusions were as following:(1)In the process of making biochar-based fertilizer with discs,the more important factors affecting the granulation and mechanical properties of fertilizers are factor C(binder species)and factor A(addition ratio of biochar and biogas slurry),then factor D(added amount of binder);while factor B(dip of pelletizer disc)and E(error term)are less important.Among the selected two kinds of self-made biochar-based fertilizer,the biochar-based fertilizer I can be made by adding bio-carbon and biogas slurry with the ratio of 100:300,using an inclination of 60° and 15g attapulgite clay,this is close to the treatment 16;the biochar-based fertilizer ? can be made by adding bio-carbon and biogas slurry with the ratio of 100:200,using an inclination of 50° and 15g sodium carboxymethyl cellulose,respectively,this is close to the treatment 10.The leaching experiments showed that the nutrient release ability of the self-made biochar-based fertilizer ? was the best.(2)The plant height,root length,root surface area and biomass of Elymus sibirictts L.,Medicago sativa L.and Poa pratensis L.were improved by using the two kinds of self-made biochar-based fertilizers.The leaf water potential,photosynthetic rate,chlorophyll content of the three plant species were also obviously improved.The transpiration rate and the stomatal conductance were decreased.In summary,the best combination for optimized plant growth is:self-made biochar-based fertilizers ?+Medicago sativa L.+300g of added fertilizer.The ideal combination for optimized physiological and biochemical characteristics of plants is:self-made biochar-based fertilizer ?+Medicago sativa L.+200g of added fertilizer.(3)The results showed that the yield of the biochar-based fertilizer was good and the economic benefits were obtained by the comprehensive analysis method.The results in promoting plant growth were as follows:plant species>self-made biochar-based fertilizer type>added fertilizer amount>Error.The most cost-effective combination is:self-made biochar-based fertilizer ?+Medicago sativa L.+200g of added fertilizer.