Analysis Of Water Extract From Biochar And Its Application On Vegetable Growth As Foliar Spray

Biomass can be converted to a carbonization product with highly aromatic structure via thermochemical processes,such as pyrolysis,gasification and hydrothermal carbonization.The application of biochar in agriculture could reduce air pollution from in-field burning,recycle nutrients and reduce chemical fertilizer inputs as well as to improve soil quality.Due to the special thermochemical process of producing biochar,there have many kinds of soluble organic and inorganic compounds in or absorbed on the surface of biochar.This study focused on the soluble compounds of biochar which produced under different process,extraction of crop straw biochars were prepared with hot water,analyzed for the composition and content of organic compounds with GC-MS,LC-OCD and FTIR,study the main factor of influencing organic compound content in water extract from biochar.Then test for their effect on plant germination,choose SW and SM for pot experiment with Chinese cabbage to study their effect on plant growth.Use the extracts at 3 different dilutions:125,1:50 and 1:100(V/V)as foliar spray during the growing period,then study their effect on cabbage yield and quality.The main conclusions are as follows:(1)The analysis of hot water extract from different biochars showed that,water-soluble fraction of biochars consists of soluble minerals,low molecule weight organic acids,low molecular weight neutrals(alcohols,aldehydes,ketones,sugars),large macromolecular organic compounds similar in character to humic substances.Content of dissolved organic carbon in hot water extract from biochar correlated with pyrolysis temperature and ash content,biochar which produced under lower pyrolysis temperature and had higher ash content contain higher content of dissolved organic carbon.(2)Over 90%dissolved organic carbon in hot water ectract from biochar were hydrophilic carbon.The fraction of hydrophilic carbon were biopolymer,humic substances,building blocks,low molecular weight neutrals and low molecular weight acids.The highest among them were humic substances,the percentage were about 60%.The second and third were building blocks and low molecular weight neutrals,about 13.05%and 8.15%respectively.(3)Hot water extract from biochar which contain high dissolved organic carbon could promote germination of cabbage under diluted 50 and 100 times.HSW diluted 50 times could promote germination rate,germination energy and germination index by 6.92%,9.67%and 18.12%.While SGM diluted 100 times could significantly increase germination energy and germination inex by 6.45%and 17.60%.(4)Use SW and SM diluted 50 or 100 times as foliar spray could promote cabbage growth,increase yield and quality.Compared with control which spray with filtered tap water,SW diluted 50 times as foliar spray could increase cabbage yield by 51.06%;promote root and root surface area by 69.43%and 77.60%;Vitamin C content was two times of control,increase soluble protein,tartaric acid and malic acid by 49.06%,56.92%and 56.90%,meanwhile decrease nitrate by 26.59%.While SM diluted 100 times could increase yield by 67.02%,significantly increase Vitamin C which was two times higher than control,it could also decrease by 36.32%.SM diluted 50 times could significantly increase protein,tartaric acid and malic acid by 60.45%,30.77%and 34.48%respectively,but showed no effect on soluble sugar.So use hot water extract from biochar diluted 50 or 100 times as foliar spray could stimulate the growth of cabbage,increase yield and quality.In this trial,the optimal treatment were SW50 and SM100.