Effects of Regular Water Replenishment on Enzyme Activities and Fungal Metabolic Function of Sheep Manure Composting on the Qinghai–Tibet Plateau

Abstract

The dry climate characteristics of the Qinghai–Tibet Plateau will seriously affect microbial metabolism during composting. In this study, we aimed to investigate the effects of regular water supplementation on the fungal and enzymatic activities of sheep manure composting in the Qinghai–Tibet Plateau. The experiment set up the treatments of water replenishment once every 7 days(T2) and 3.5 days (T3) days, and no water supplementation was used as the control (T1). The results showed that regular water supplementation increased the activities of various enzymes during composting, and the activities of protease, cellulase, peroxidase and polyphenol oxidase in T3 were higher than those in T2. Regular water supplementation increased the relative abundance of Remersonia and Mycothermus, which were significantly positively correlated with the germination index, and degradation of organic components. Regular water supplementation could enrich fungi carbohydrate, protein, and nucleotide metabolisms, and T3 had a better effect. A redundancy analysis showed that environmental factors could significantly affect the fungal community; among them, moisture content (76.9%, p = 0.002) was the greatest contributor. In conclusion, regular water supplementation can improve the key enzyme activities and fungal metabolic function of sheep manure composting, and water replenishment once every 3.5 days had the best effect.

Effects of turning frequency on fermentation efficiency and microbial community metabolic function of sheep manure composting on the Qinghai–Tibet Plateau

“…The C/N ratio, E 4 /E 6 ratio and germination index (GI) are commonly used to evaluate the toxicity degree and maturity of compost (Awasthi et al 2020a ). The C/N and E 4 /E 6 ratio are negatively correlated with compost maturity, while GI is positively correlated with maturity (Cai et al 2022 ). As shown in Fig.…”

“…The Chao1 and the observed species indices were calculated to assess richness, and the phylogenetic diversity (PD) whole tree and Shannon indices were calculated to reflect the diversity (Cai et al 2022 ; Zhou et al 2022 ). As shown in Fig.…”

“…3 c, Ascomycota was the most important fungus phyla in the whole composting process (82.4–98.9%). Ascomycota has good high-temperature adaptability and can utilize a variety of carbon sources, and is considered the dominant phylum in lignocellulosic compost ecosystems (Zhang et al 2011 , 2021a ; Cai et al 2022 ). The relative abundance of Ascomycota in T2 was slightly lower than that in T3 and T4 during composting, but the fungal richness in T2 was significantly higher than that in T3 and T4 (Fig.…”

“…Melanocarpus , Mycothermus , and Metschnikowia were also the main fungi in the early stage. It has been reported that these fungi can catalyze the degradation of organic components by secreting different enzymes during the thermophilic phase of composting (Duan et al 2021 ; Feng et al 2021a ; Cai et al 2022 ). On the 4th to 12th day, the relative abundance of Candida , Aspergillus , Cyberlindnera , Metschnikowia , Penicillium , and Talaromyces declined, while the abundance of Melanocarpus , Stolonocarpus , Remersonia , and Mycothermus increased rapidly.…”

“…The temperature was measured at 9:00 AM and 16:00 PM each day (Cai et al 2022 ). Digital thermometers were evenly inserted into 8 positions on the upper (20 cm), middle (60 cm), and lower (100 cm) layers of the composting pile to calculate the average temperature of the 24 positions.…”