IntroductionThe development of organic manure from livestock excreta is a useful source for sustainable crop production in environment-friendly agriculture. Organic manure increases soil microbial activity and organic matter (OM) supply. The excessive use of chemical fertilizers (CFs) leads to air and water pollution caused by toxic chemicals and gases, and soil quality degradation via nutrient imbalance due to supplying specific chemical components. Thus, the use of organic manure will serve as a long-term supply of various nutrients in soil via OM decomposition reaction as well as the maintenance of environment.MethodsIn this study, we aimed to analyze the diverse effects of Hanwoo manure (HM) on plant growth, feed quality, and soil bacterial communities in comparison with CFs, commercial poultry manure (CM), and the combined use of chemical fertilizer and Hanwoo manure (HM+CF). We analyzed the contents of crude matter (protein, fat, fiber, and ash), P, acid detergent fiber (ADF), and neutral detergent fiber (NDF) through feed quality analysis, and the contents or activities of total phenol, total flavonoid, ABTS, nitrite scavenging, and reducing power via the antioxidant assay. Furthermore, the soil microbial communities were determined using 16S rRNA sequencing. We compared the soil bacteria among different soil samples by using amplicon sequence variant (ASV) analysis.Results and discussionWe observed increased OM in the soil of the HM group compared to that of the CF and non-treated groups over a period of two years. Moreover, HM+CF treatment enormously improved plant growth. Organic manure, especially HM, caused an increase in the content of crude ash and phosphorus in plants. There were no significant differences in total polyphenol, total flavonoid, ABTS, nitrite scavenging, and reducing power in plants between HM and CF groups. Finally, we detected 13 soil bacteria (Acidibacter, Algisphaera, Cystobacter, Microvirga, Ohtaekwangia, Panacagrimonas, Pseudarthrobacter, Reryanella, Rhodoligotrophos, Solirubrobacter, Stenotrophobacter, Tellurimicrobium, and Thermomarinilinea) that were considerably correlated with OM and available phosphorus, and three considerably correlated bacteria were specifically distributed in CF or organic manure. The results suggest that HM is a valuable source of organic manure that can replace CF for sustainable crop production.

IntroductionFennel (Foeniculum vulgare Mill.) is widely used to produce natural bio-materials. Elevated CO2 (eCO2) concentrations in the atmosphere improve the net photosynthesis of plants.MethodsThe aim of the present study was to investigate distinct changes in fennel growth characteristics and phytonutrient contents under different CO2 concentrations. The effects of 400 and 800 ppm concentrations on plant growth and antioxidant activity were observed under hydroponics.Results and DiscussionPlant growth was improved by eCO2 concentrations. We also observed diverse changes in nutrient solution (pH, electrical conductivity, and dissolved oxygen) and environmental factors (temperature and humidity) in greenhouse under light or dark conditions. Electrical conductivity increased under dark and eCO2 conditions, whereas the pH decreased. Additionally, we performed transcriptome analysis and identified CO2-responsive differentially expressed genes. In the 800 ppm group, genes involved in photosynthesis and Karrikin response were upregulated whereas those involved in syncytium formation were downregulated. Four upregulated differentially expressed genes involved in flavonoid biosynthesis and total flavonoid content were relatively increased under the 800 ppm CO2 condition. In contrast, antioxidant activity, including total phenolic content, scavenging activity, ferric ion reducing antioxidant power, and reducing power were decreased in fennel under relatively high eCO2 concentrations. Moreover, different light intensities of 12 or 24 lx did not affect the growth and antioxidant activity of fennel, suggesting eCO2 has a stronger effect on plant improvement than light intensity. The results of the present study enhance our understanding of the positive effects of CO2 on the growth and antioxidant activity of fennel.

Background 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 rapa subsp. Pekinensis). Results Three liquid fertilizers, chemical liquid fertilizer (CLF), fermented liquid manure (FLM) from pig droppings, and liquid bio-fertilizer (LBF) from Chlorella cultured 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.