Influence of organic liquid fertilizer developed from livestock manure on the growth, antioxidant activities, and soil microbial populations of Chinese cabbage

Abstract

AbstractBackground Effluents from livestock excretion have worldwide environmental disadvantages, such as air and water pollution. However, livestock manure and organic liquid fertilizers developed for the proper management of livestock excretions can be used as environmentally friendly fertilizers for sustainable agriculture. Therefore, we investigated the effects of organic liquid fertilizers on the growth and antioxidant accumulation in Chinese cabbage (Brassica rapasubsp.Pekinensis). Results Three liquid fertilizers, chemical liquid fertilizer (CLF), fermented liquid manure (FLM) from pig droppings, and liquid bio-fertilizer (LBF) fromChlorellacultured in purified organic liquid manure, were used in this experiment. Plant performance was observed and soil microbial changes caused by these liquid fertilizers were analyzed using 16S rRNA sequencing. We observed the highest plant growth in terms of plant length, chlorophyll concentration, width and length of leaves, and fresh and dry weights in the CLF group. LBF led to improved plant growth compared to FLM. Chlorophyll concentrations and color measurements of the plants were higher with LBF than with FLM. Interestingly, LBF affected plant substances with respect to sugar, ascorbic acid, and antioxidants in Chinese cabbage compared to CLF and FLM. The highest total polyphenol and flavonoid content, antioxidant activity, nitrite-scavenging capacity, and reducing power were observed in the LBF group. Significant changes in the bacterial population were observed in amplicon sequence variant analysis; the presence of Verrucomicrobia increased in soils after FLM and LBF treatments. LBF-treated soils had a higher abundance of Proteobacteria than FLM-treated soils. Conclusions We studied the effects of organic fertilizers across different liquid fertilizers on plant growth, antioxidants, and soil microorganisms. Especially, the LBF as organic bio-liquid fertilizer improved the plant growth and substances in Chinese cabbage under a controlled environment agriculture system. We have identified the specific bacterial species regarding the production process of liquid fertilizers in the change of soil microbial communities by the short-term experimental treatment. Thus, the proper development of organic bio-liquid fertilizer can contribute to the organic waste-recycling systems of livestock excretions for sustainable agriculture.