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The goal of this experiment was to investigate the effect of aeration quantity (0, 11, 33, 55, and 77 L·min−1) on the growth of aerated compost extracts from a pig manure–straw compost. When the aeration quantity was 11 L·min−1, lettuce root growth enhancement of normalized compost extracts was at a maximum. As the aeration quantity increased, the total water-soluble organic carbon (TWSOC), total nitrogen (TN), total phosphorus (TP), humic carbon (humic C) content, and humification degree of compost extracts improved gradually. No differences in functional group structure were found among the aerated compost extracts. The positive root growth could be attributed to physicochemical and spectral characteristics, such as TN content, humic substances content, humification, aromaticity, and the low content of carboxyl groups. In conclusion, the aeration quantity of 11 L·min−1 was suitable for the production of aerated compost extracts, which obtained much greater promotion growth.

Integrated rice–crayfish farming system is a highly efficient artificial ecosystem in which the rice (Oryza sativa) variety ‘Jianzhen 2′ is cultivated in waterlogged paddy fields along with crayfish (Procambarus clarkii). We investigated soil carbon fractions and microbial community structure by phospholipid fatty acids (PLFA) analysis in a 10-year field experiment using an integrated rice–crayfish (CR) model and a rice monoculture (MR) model at soil depths of 0–10 cm, 10–20 cm, 20–30 cm, and 30–40 cm. Compared with the MR model, the CR model had significantly more total organic carbon, particulate organic carbon, and dissolved organic carbon contents in all of the layers examined and microbial biomass carbon content in the 20–40 cm layer. Principal components analysis revealed that microbial community composition in the CR model differed from that in the MR model in the 20–30 cm layer. Higher proportions of gram–negative bacteria, aerobic bacteria and fungi in the 20–30 cm soil layer were observed for the CR model than the MR model. These results indicate that the CR model increases soil carbon levels, and strongly affects microbial community composition and structure in the deeper layers of soil, thereby accelerating subsurface soil nutrient cycling.

Pig manure rice straw compost was extracted using different extraction methods, and the composition of each extraction was identified by chromatogram and spectroscopy in order to investigate plant growth promoting factors. Compared with direct extraction, aerated and non-aerated fermentation extractions were better for nutrient accumulation, especially for high molecular weight substances. Cucumber yields of aerated fermentation extraction of compost (AFEC) treatment were 16.5 and 57.6 % higher than the direct extraction of compost (DEC) and non-aerated fermentation extraction of compost (NAFEC) treatments. Humic acid-like and fulvic acid-like substances were the main components in all extracts. Furthermore, AFEC showed the most humification and aromatization. Humic substances extracted from AFEC (H-AFEC) increased shoot dry weight by 2.8 and 7.4 %, compared to humic substances extracted from DEC (H-DEC) and humic substances extracted from NAFEC (H-NAFEC). In conclusion, AFEC was the best extraction method to get more humic substances to stimulate plant growth.

Various parameters were measured during the period of composting of dairy manure and rice chaff in different ratios (dairy manure/rice chaff=V/V, pile 1: 75/25; pile 2: 80/20; pile 3: 85/15) to evaluate their suitability as indicators for the composting process. The temperature in pile 1 increased rapidly and remained above 60 °C for 30 days, while the temperature in pile 3 increased slowly relative to the other two piles. Furthermore, the degradation of organic substrates, as indicated by the reduction of C/N ratio, was rapid in pile 1 (below 20% 28 days after beginning of the composting). The major fluctuations of various water-soluble fractions in all piles were observed during the first 3 weeks, and the results in general showed that the highest microbial populations and enzymatic activities also appeared in this phase. Various parameters indicated that the rapid composting method was a feasible one for treating agricultural wastes.

A lignocellulosic decomposing fungus Z5 was isolated and identified as Aspergillus fumigatus, its capacity to produce cellulase was assessed under solid-state fermentation (SSF) using lignocellulosic materials as substrates. Cultivation conditions of A. fumigatus Z5 for cellulase production were optimized, results showed that for carboxymethyl cellulase (CMCase) and filter paper enzyme (FPase), the best condition was 50 °C, 80% initial moisture, initial pH 4.0 and 7% initial inoculum, the average activity of CMCase activity, FPase activity reached 526.3 and 144.6 U g−1 dry weight (dw) respectively, much higher than most of previous reports of this genus. Optimal temperature and pH for the CMCase activity of the crude enzyme were found to be 50 °C and 5.0, respectively. Zymogram analysis showed that eight kinds of CMCase were secreted by A. fumigatus Z5 when cellulose-containing materials were supplied in the culture. The crude enzyme secreted by the strain was further applied to hydrolyze pretreated corn stover and the enzymatic hydrolysate was used as substrate for ethanol production by Saccharomyces cerevisiae. The yield of bio-ethanol was 0.112 g g−1 dry substrate (gDS), suggesting that it is a promising fungus in the bio-ethanol production process.

Assessment of compost maturity is essential for achieving high quality compost. In this study, fluorescence excitation-emission matrix spectroscopy combined with different analysis techniques was applied to improve the sensitivity of compost maturity assessment. Results showed that composts in two parallel piles could be believed mature after 37d when combined with the evolution of temperature, chemical and biological indices in the two piles. Pearson correlation between the common maturity indices and fluorescence analysis parameters demonstrated that fluorescence regional integration (FRI) had a higher correlation coefficient than that of fluorescence intensities and the ratios of peaks, suggesting that FRI technique is more suitable to characterize the maturity of compost than the other two analysis techniques, i.e., peak intensity and peak ratio. Furthermore, the fluorescence spectroscopy combined with FRI analysis could be used as a valuable industrial and research tool for assessing compost maturity.