Preparation And Performances Of Biochar Microbial Sustained Fertilizers

Concern is mounting that the two types of fertilizers,named as sustained release fertilizer and microbial fertilizer,would improve the defects known as heavy resource waste and serial environment pollution,especially the soil contamination,always caused by the conventional fertilizer.To satisfy the nutrition requirement and supplement the microorganism in the duration of the corn growth in time,a type of sustained release fertilizer prepared from the combination of conventional fertilizer and microorganism was added in the soil together with the seeds in that spring ploughing time.The sustained release fertilizer referred in this paper was prepared through the embedding method that the material resembled polyvinyl alcohol and sodium alginate was used to include the bacillus subtilis and compound fertilizer.It is a novel type of microorganism sustained release fertilizer.The study on the prepared microorganism sustained release fertilizer was conducted in four aspects,the influence of the chemical fertilizer exerted on the growth behavior of the microorganism,the optimization of the embedding material,the relationship between the bead characterization,including the release behavior of chemical fertilizer and microorganism,and the medium,mainly rice husk or biomass charcoal which is used to regulate the micro-porosity,and the actual result of the fertilizer treatment under farm experiment.The chemical fertilizer researched here should be nitrogen fertilizer,phosphatic fertilizer and potash fertilizer and the microorganism should be bacillus subtilis.It was showed that:(1)The growth behavior of the bacillus subtilis is greatly influenced by the concentration of urea and dipotassium phosphate,the numbers of bacillus subtilis decreased dramatically when the urea concentration exceeds 6% of nutrient medium or slighter when the dipotassium phosphate concentration exceeds 1%.It was confirmed that the concentration of urea and dipotassium phosphate should be 6% and1% respectively,the ration of the two is Urea: KH2PO4=6:1(N:K:P=5.6:3:1).(2)The optimization should be conducted from the concentration and fixed time of the polyvinyl alcohol,sodium alginate,boric acid and calcium chloride.The beadcharacterization,swelling ratio,embedding ratio and release condition are primary evaluation indicator.It was found that all the characters of the bead like viscosity,operability,swelling ratio and embedding ratio are closely related to the concentration of polyvinyl alcohol and sodium alginate.It was chosen for the optimized bead characteristic with the concentration of sodium alginate 1.5% and polyvinyl alcohol3%.The bead forms ball perfectly when the concentration of boric acid is 4% and the calcium chloride 2%,the boric acid plays the role as fixed agent in the preparation process.The fixed time for the bead decides its mechanical strength and embedding ratio,and is set to one hour to obtain the satisfying embedding ratio.(3)It is convenient for the storage of fertilizer and microorganism if adding rice husk or biomass charcoal in the bead preparation process.The comparison of which one shows excellent performance in bead characteristics,fertilizer and microorganism release capability between them are analyzed through static water releasing test and soil column test.Scanning electron microscope indicated that all of the beads obtained from the both material is oval,but the ones mixed by the rice husk showed more rough surface and intense porosities which is more advantageous in material exchange like nutrients outside the bead goes in and metabolite is expelled to the outside.It showed that the accumulated release amount of urea reached 76.62% and the potassium dihydrogen thophosphate 62.82% in the bead prepared with rice husk at the concentration of 4%.The value was 71.38% and 69.34% respectively in the bead prepared with biomass charcoal at the same concentration condition.The accumulated release amounts of urea and potassium dihydrogen thophosphate was 61.11% and63.49% respectively in the bead prepared with rice husk and in the bead prepared with biomass charcoal the accumulated amounts was 65.49% and 72.31% after an up to ninety-two days’ soil column leaching release test.(4)The influence on the growth of corn with six samples of microorganism fertilizer treated through different method was researched.The result showed that the fertilizer with embedding treatment released sustainedly during the seeding stage of the corn and rose rapidly as it grew,which satisfied the requirement appropriately.The maximum value of thousand kernel weight and bulk density of the corn,285.49 gand 747g/L,emerged in the field fertilized by the microorganism sustained release fertilizer whose embedding agent was mixed with biomass charcoal.This means it increases the microorganism and improves soil excellently.