Humification process of bio-dried kitchen waste composting and evaluation of humic acid activity
This study aimed to examine the process of preparing biochemical humic acid from bio-dried kitchen waste via composting,explore the optimal yield pathway,and evaluate the activity of its biochemical humic acid.The study was conducted by setting up three groups of composting treatments of C/N 25(CN25),20(CN20),and 15(CN15)using kitchen waste after initial fermentation of bio-drying,which was used as the main material and sawdust as the auxiliary material.We selected the treatment with the largest humic acid yield in compost.Biochemical humic acid was extracted with degrees of putrefaction set at 50%and 80%(germination index,GI)with varying application concentrations 0(Y),20,40 mg·L-1,and 80 mg·L-1.We used 40 mg·L-1 mineral humic acid as the control(H)to investigate the pattern of humic acid production through the determination of humification indices.Furthermore,agronomic indicators of maize were applied to the hydroponic test.All three composting treatments met the basic putrefaction requirement(GI≥50%),and the humus,humic acid,and fulvic acid contents showed a decreasing trend.At the end of composting,the humus content of the CN20 treatment was 155.6%and 91.7%higher than that with the CN25 and CN15 treatments,respectively.The content of humic acid observed with the CN20 treatment was 170.3%and 98.0%higher than that with the CN25 and CN15 treatments,respectively.The fulvic acid content observed with the CN20 treatment was 150.0%and 57.9%higher than that with the CN25 and CN15 treatments,respectively.All aforementioned results showed significant differences(P<0.05).The ratio of humic acid to fulvic acid with CN20 was 9.0%and 23.4%higher than that of CN25 and CN15,respectively,and the percentage of humic acid was 1.2%and 3.1%higher than that of CN25 and CN15.Low maturity(GI-50%)was associated with the highest humic acid yield,and humus,humic acid,and fulvic acid contents were 64.3%,57.6%,and 73.5%higher in the compost at low degree of spoilage(GI-50%)than at high degree of spoilage(GI-80%).When applied at a concentration of 40 mg·L-1,biochemical humic acid showed significant enhancement of maize shoot dry weight,plant height,chlorophyll content,leaf area,root dry weight,and total root tip number compared to mineral humic acid(P<0.05).The order of maize integrated growth was GI-50%-20>GI-50%-40>GI-80%-40>GI-50%-80>GI-80%-20>H>GI-80%-80>Y.The application of humic acid could promote the growth of maize.The application of biochemical humic acid with a low humic concentration of 20 mg·L-1 exhibited the most significant effect on maize growth promotion(P<0.05).Composting with a C/N ratio adjusted to 20 yields the highest humic acid production,especially when subjected to basic decomposition(GI-50%).Extracting biochemical humic acid from this source and applying it to corn at a concentration of 20 mg·L-1 results in the most effective promotion of growth with enhanced biological activity.
bio-dried kitchen wastehumification processcomposting maturityactivity of biochemical humic acid
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维普
