[Effects of Straw Returning with Lime on SOC and Carbon Pool Management in Acidic Paddy Soil].

Soil acidification and low SOC are the main limiting factors in acidic paddy soils. Straw returning with lime is an effective measure to alleviate soil acidification and improve soil fertility; however, its interaction effects on SOC and carbon pool management are still unclear. To investigate the impact of straw returning with lime on the organic carbon pool of acidic paddy soil, field experiments were conducted on acidic paddy soil in Baiyun District and Huiyang District of Guangdong Province. The changes in soil total organic carbon (TOC), water-soluble organic carbon (DOC), active organic carbon (LOC), particulate organic carbon (POC), microbial biomass carbon (MBC), carbon pool index (CPI), stable organic carbon (IOC), carbon pool activity (L), carbon pool activity index (CPAI), and carbon pool management index (CPMI) were analyzed under three treatments (CK, conventional fertilization; RS, straw returning+conventional fertilization; RS+L straw returning with lime+conventional fertilization). The results demonstrated that compared with that in CK, the TOC, LOC, POC, and MBC in the RS+L treatment were significantly increased by 10.24%-17.79%, 34.49%-44.37%, 19.27%-23.59%, and 33.36%-43.26%, respectively (P<0.05). Compared with that in CK, the RS+L treatment significantly increased the DOC content during the early growth stage (15-45 days after transplanting) of rice (P<0.05) but had no significant influence on the DOC content during the late growth stage of rice. Compared with that in RS, the TOC, LOC, POC, and MBC in the RS+L treatment were increased by 2.15%-6.95%, 1.17%-17.90%, 4.27%-8.65%, and 12.99%-14.53%, respectively. Compared with that in CK, the RS+L treatment significantly increased IOC and CPI by 8.32%-15.57% and 14.00%-20.00%, respectively (P<0.05). Compared with that in the CK treatment, the RS treatment significantly increased CPI by 14.00%-18.00% (P<0.05). No significant differences in L, CPAI, or CPMI were detected among the different treatments. The soil pH in the RS+L treatment was significantly higher than that in the CK treatment (P<0.05). No significant differences in rice yield were detected among the different treatments. Principal component analysis demonstrated that rice yield was primarily correlated with DOC, LOC, CPAI, and CPMI but its contribution to SOC and carbon pool management index was low. Principal component analysis also indicated that straw returning with lime could improve soil pH and nutrient contents of acidic paddy soil, driving the formation and accumulation of organic carbon fraction such as MBC and POC, thus boosting the increase in SOC. In conclusion, straw returning with lime is beneficial to the accumulation of MBC, POC, LOC, and IOC in acidic paddy soil to improve the content and stability of soil total organic carbon, which is an effective way to improve the carbon sequestration of acidic paddy soil.

[Effects of Early Rice Straw Returning with Reducing Potassium Fertilizer on Late Rice Yield and Soil Fertility].

Rice straw is an important organic fertilizer in the region for double-cropping rice in South China. To reveal the effects of early rice returning with reducing potassium fertilizer on the yield of late rice and soil fertility, field experiments were carried out in Baiyun and Huiyang district in Guangdong province. The biomass, K content, and yield of late rice and the soil fertility properties, such as soil available potassium, soil organic carbon, bacterial diversity, and bacterial community structure were analyzed under three treatments (CK, conventional fertilization; RS, straw returning with conventional fertilization; RS-K, straw returning with reducing 20% potassium fertilizer). The results showed no significant differences in the biomass and yield of late rice between the RS-K treatment and CK treatment. Compared with that in CK, the RS treatment significantly increased the K contents of rice by 3.97% (Baiyun) and 6.91% (Huiyang). The K contents of late rice under the RS-K treatment were significantly lower than that under the CK treatment during the early growth period in rice, but there was no significant difference between them during the late growth period. Compared with that in CK, the soil available K in the RS treatment increased by 13.90% (Baiyun) and 21.67% (Huiyang) (P<0.05), and the soil available K in the RS-K treatment also increased by 3.56% (Baiyun) and 4.23% (Huiyang). Compared with that in the CK treatment, the soil dissolved organic carbon increased significantly in the RS and RS-K treatments (P<0.05). Compared with that in CK, the straw returning treatments (RS and RS-K) significantly improved the Chao1 and Shannon indexes of soil bacteria (P<0.05). Straw returning treatments (RS and RS-K) increased the relative abundance of Proteobacteria, Actinobacteria, and Nitrospirae compared with that in CK, whereas they decreased the relative abundance of Acidobacteria, Bacteroidetes, and Firmicutes. Redundancy analysis showed that the soil bacterial community was mainly influenced by soil organic carbon, dissolved organic carbon, microbial biomass carbon, available P, and available K. In summary, early rice returning could increase soil available K and K content in late rice. Early rice straw returning with reducing potassium fertilizer had no negative impacts on the growth and yield of late rice and could also improve soil organic carbon and the diversity of soil bacteria. Therefore, early rice straw returning with reducing potassium fertilizer can guarantee the grain yield of late rice and improve soil fertility.

Pre-sowing seed treatment with kinetin and calcium mitigates salt induced inhibition of seed germination and seedling growth of choysum (Brassica rapa var. parachinensis).

In recent years, improving plants' resistance towards abiotic stresses with exogenous application of plant growth regulators and nutrients has emerged as a matter of great interest. The present study assessed the potential roles of kinetin (Kn, 0.2 mM) and calcium (Ca, 2 mM) in mitigating the salt (200 mM NaCl) induced inhibitory effects on seed germination and growth of choysum seedlings. The results indicated that NaCl stress significantly reduced the seed germination percentage (42.6%), germination potential (42.0%), germination index (52.1%), seedling vigor index (65.2%), and declined the fresh weight (43.8%), dry weight (52.2%), radicle length (37.2%), and plumule length (41.2%) of germinated seeds, compared to control treatment. The delayed germination and decrease in seedling growth were positively correlated with salinity-induced hormonal imbalance, ion toxicity, and oxidative stress. However, Kn and Ca pretreatment partially mitigated the adverse effects of NaCl stress, evident by early germination and enhanced seedling growth. Kn and Ca effectively increased the accumulation of proline, soluble protein, and soluble sugars, and upregulated the activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase that significantly reduced the production of malondialdehyde, hydrogen peroxide, and superoxide anions in germinating seeds, thereby minimizing the NaCl-induced oxidative damages. Moreover, Kn and Ca pretreatment counteracted the NaCl-induced ionic toxicity by decreasing Na+ and increasing K+ contents and maintained a balanced Na+/K+ ratio in radicles and plumules of choysum seeds. Additionally, Kn and Ca under NaCl stress enhanced hormonal regulation by decreasing the ABA levels with a concomitant increase of GAs (especially GA4) levels and promoted early germination. Remarkably, the co-application of Kn and Ca was most effective by completely counteracting the inhibitory effects of NaCl and maintaining seed germination kinetics, seedling growth, and biochemical parameters almost similar to that in the stress-free control treatment. These results demonstrate that supplementation of Kn and Ca on choysum seeds is an effective chemical strategy regulating the various physiological and biochemical responses that would result in better germination and growth of seeds under stress conditions.

Jasmonic acid-mediated enhanced regulation of oxidative, glyoxalase defense system and reduced chromium uptake contributes to alleviation of chromium (VI) toxicity in choysum (Brassica parachinensis L.).

The cultivation of leafy vegetables on metal contaminated soil embodies a serious threat to yield and quality. In the present study, the potential role of exogenous jasmonic acid (JA; 0, 5, 10, and 20 µM) on mitigating chromium toxicity (Cr; 0, 150, and 300 µM) was investigated in choysum (Brassica parachinensis L.). With exposure to increasing Cr stress levels, a dose-dependent decline in growth, photosynthesis, and physio-biochemical attributes of choysum plants was observed. An increase in Cr levels also resulted in oxidative stress closely associated with higher lipoxygenase activity (LOX), hydrogen peroxide (H2O2) generation, lipid peroxidation (MDA), and methylglyoxal (MG) levels. Exogenous application of JA alleviated the Cr-induced phytotoxic effects on photosynthetic pigments, gas exchange parameters, and restored growth of choysum plants. While exposed to Cr stress, JA supplementation induced plant defense system via enhanced regulation of antioxidant enzymes, ascorbate and glutathione pool, and the glyoxalase system enzymes. The coordinated regulation of antioxidant and glyoxalase systems expressively suppressed the oxidative and carbonyl stress at both Cr stress levels. More importantly, JA restored the mineral nutrient contents, restricted Cr uptake, and accumulation in roots and shoots of choysum plants when compared to the only Cr-stressed plants. Overall, the application of JA2 treatment (10 µM JA) was more effective and counteracted the detrimental effects of 150 µM Cr stress by restoring the growth and physio-biochemical attributes to the level of control plants, while partially mitigated the detrimental effects of 300 µM Cr stress. Hence, JA application might be considered as an effective approach for minimizing Cr uptake and its detrimental effects in choysum plants grown on contaminated soils.

Comparative effectiveness of Se translocation between low-Se and high-Se rice cultivars under Se fertilization.

The production of natural selenium (Se)-rich food by using a high-Se crop cultivar is beneficial to human health and environmental safety; however, the underlying mechanism of different Se-accumulation ability between high- and low-Se rice cultivars remains unclear. A low-grain-Se cultivar and high-grain-Se cultivar of rice were used as test materials, and two levels of Se (0 and 0.5 mg kg-1) were arranged in a randomized design containing twelve replicates. The dynamic changes of shoot Se concentration and accumulation, xylem sap Se concentration, shoot and grain Se distribution, Se transporters genes (OsPT2, Sultr1;2, NRT1.1B) expression of the high- and low-Se rice cultivars were determined. The shoot Se concentration and accumulation of the high-Se rice showed a greater degree of reduction than those of the low-Se rice during grain filling stage, indicating that leaves of high-Se rice served as a Se source and supplied more Se for the growth centre grain. The expression levels of OsPT2, NRT1.1B and Sultr1;2 in the high-Se rice cultivar were significantly higher than those in the low-Se rice cultivar, which indicated that the high-Se rice cultivar possessed better transport carriers. The distribution of Se in grain of the high-Se rice cultivar was more uniform, whereas the low-Se cultivar tended to accumulate Se in embryo end. The stronger reutilization of Se from shoots to grains promoted by increased transporters genes expression and optimized grain storage space may explain how the high-Se rice cultivar is able to accumulate more Se in grain.

Modulation of growth performance and coordinated induction of ascorbate-glutathione and methylglyoxal detoxification systems by salicylic acid mitigates salt toxicity in choysum (Brassica parachinensis L.).

Salinity represents a serious environmental threat to crop production and by extension, to world food supply, social and economic prosperity of the developing world. Salicylic acid (SA) is an endogenous plant signal molecule involved in regulating various plant responses to stress. In the present study, we characterized the regulatory role of exogenous SA for their ability to ameliorate deleterious effects of salt stress (0, 100, 150, 200 mM NaCl) in choysum plants through coordinated induction of antioxidants, ascorbate glutathione (AsA-GSH) cycle, and the glyoxalase enzymes. An increase in salt stress dramatically declined root and shoot growth, leaf chlorophyll and relative water content (RWC), subsequently increased electrolyte leakage (EL) and osmolytes accumulation in choysum plants. Salt stress disrupted the antioxidant and glyoxalase defense systems which persuaded oxidative damages and carbonyl toxicity, indicated by increased H2O2 generation, lipid peroxidation, and methylglyoxal (MG) content. However, application of SA had an additive effect on the growth of salt-affected choysum plants, which enhanced root length, plant biomass, chlorophyll contents, leaf area, and RWC. Moreover, SA application effectively eliminated the oxidative and carbonyl stress by improving AsA and GSH pool, upregulating the activities of antioxidant enzymes and the enzymes associated with AsA-GSH cycle and glyoxalase system. Overall, SA application completely counteracted the salinity-induced deleterious effects of 100 and 150 mM NaCl and partially mediated that of 200 mM NaCl stress. Therefore, we concluded that SA application induced tolerance to salinity stress in choysum plants due to the synchronized increase in activities of enzymatic and non-enzymatic antioxidants, enhanced efficiency of AsA-GSH cycle and the MG detoxification systems.

Effects of sulphur and Thiobacillus thioparus 1904 on nitrogen cycle genes during chicken manure aerobic composting.

Severe nitrogen (N) loss is a barrier for composting treatment. Since N transformation during composting is closely related to nitrogen loss, the impacts of adding sulphur and Thiobacillus thioparus 1904 to N transformation during composting were investigated in this work. Physicochemical properties and the expression of genes encoding N-related proteins were analysed to evaluate microbiological processes associated with N dynamics. The results indicated that (1) sulphur addition reduced the pH and cumulative NH3 emission, and decreased N losses by 44.23%, while no significant differences were observed in the expression of N cycle-associated genes compared with the control treatment; (2) the application of T. thioparus 1904 increased NO3--N content, reduced N loss by 28.20%, and significantly enhanced the expression of ammonia monooxygenase A (archaeal amoA; AOA) and nitrite oxidoreductase A (nxrA) during the mature phase; (3) the combined application of sulphur and T. thioparus 1904 significantly affected the expression of functional genes related to nitrification and denitrification, which contributed to a reduction in accumulated NH3 emission, an increase in NO4+-N content, and a decrease in N losses by 70.94%. Expression of ammonia monooxygenase A (bacterial amoA; AOB), nxrA and nitrous oxide reductase Z (nosZ) genes in the combined treatment was positively correlated with NO3--N, whereas expression of AOA and accumulation of NH3 were negatively correlated with NO3--N. These results indicate that the combined application of sulphur and T. thioparus 1904 had a significant regulatory effect on N cycle genes and effectively reduced the N loss during composting.

Effect of Thiobacillus thioparus 1904 and sulphur addition on odour emission during aerobic composting.

The effects of sulphur and Thiobacillus thioparus 1904 on odour emissions during composting were studied. Results indicated that the sulphur addition reduced the pH and decreased cumulative emission of ammonia and the nitrogen loss by 47.80% and 44.23%, respectively, but the amount of volatile sulphur compounds (VSCs) and the sulphur loss increased. The addition of T. thioparus 1904 effectively reduced the cumulative emissions of H2S, methyl sulphide, methanethiol, dimethyl disulphide and the sulphur loss by 33.24%, 81.24%, 32.70%, 54.22% and 54.24%, respectively. T. thioparus 1904 also limited the nitrogen loss. The combined application of sulphur and T. thioparus 1904 resulted in the greatest amount of nitrogen retention. The accumulation of ammonia emissions was reduced by 63.33%, and the nitrogen loss was reduced by 71.93%. The combined treatment did not increase the emission of VSCs. The application of sulphur and T. thioparus 1904 may help to control the odour of compost.

Fungi diversity from different depths and times in chicken manure waste static aerobic composting.

The Dirichlet multinomial mixtures mode was used to analyse illumina sequencing data to reveal both temporal and spatial variations of the fungi community present in the aerobic composting. Results showed that 670 operational taxonomic units (OTUs) were detected, and the dominant phylum was Ascomycota. There were four types of samples fungi communities during the composting process. Samples from the early composting stage were mainly grouped into type I and Saccharomycetales sp. was dominant. Fungi community in the medium composting stage were fallen into type II and III, Sordariales sp. and Acremonium alcalophilum, Saccharomycetales sp. and Scedosporium minutisporum were the dominant OTUs respectively. Samples from the late composting stage were mainly grouped into type IV and Scedosporium minutisporum was the dominant OTU; Scedosporium minutisporum was significantly affected by depth (P<0.05). Results indicate that time and depth both are factors that influence fungi distribution and variation in c waste during static aerobic composting.

Effects of supplementary composts on microbial communities and rice productivity in cold water paddy fields.

Cold water paddy field soils are relatively unproductive, but can be ameliorated by supplementing with inorganic fertilizer from animal waste-based composts. The yield of two rice cultivars was significantly raised by providing either chicken manure or cow dung-based compost. The application of these composts raised the soil pH as well as both the total nitrogen and ammonium nitrogen content, which improved the soil's fertility and raised its nitrification potential. The composts had a measurable effect on the abundance of nitrogencycling- related soil microbes, as measured by estimating the copy number of various bacterial and archaeal genes using quantitative real-time PCR. The abundance of ammonia oxidizing archaea and bacteria was markedly encouraged by the application of chicken manure-based compost. Supplementation with the composts helped promote the availability of soil nitrogen in the cold water paddy field, thereby improving the soil's productivity and increasing the yield of the rice crop.

[Adsorption-desorption Characteristics of Fermented Rice Husk for Ferrous and Sulfur Ions].

To understand the potential of rice husk to fix Fe2+ and S2- ions, the sorption of Fe2+ and S2- by fermented rice husk was studied by using batch incubation experiments in the present study. The effects of adsorption time, Fe2+ and S2- concentration, pH, the temperature and ionic strength in adsorption reaction solution on the sorption were investigated. Therefore, the stability of Fe2+ and S2- adsorbed by fermented rice husk was further validated by desorption experiments performed under similar conditions as adsorption. The results showed that, the adsorption kinetics of Fe2+ (r = 0.912 1) and S2- (r = 0.901 1) by fermented rice husk fits the Elovich kinetics equation, and Freundlich isotherm model could simulate the isotherm adsorption processes of Fe2+ (R2 = 0.965 1) and S2- (R2 = 0.936 6) on fermented rice husk was better than other models. The adsorption processes on fermented rice husk were non- preferential adsorption for Fe2+ and S2, while the adsorption process of Fe2+ on fermented rice husk was spontaneous reaction and the adsorption process of S2- was non-spontaneous reaction. The adsorption processes of Fe2+ and S2- on fermented rice husk were endothermic process since high temperature could benefit to the adsorption. The adsorption mechanism of Fe2+ on fermented rice husk was mainly controlled by coordination adsorption, the adsorption mechanism of S2- on fermented rice husk was mainly controlled by ligand exchange adsorption. The adsorption processes of Fe2+ and S2- on fermented rice husk showed greater pH adaptability which ranged from 1.50 to 11.50. With the increasing of ionic strength, the amount of adsorbed Fe2+ on fermented rice husk wasincreased in some extent, the amount of adsorbed S2- on fermented rice husk was slightly decreased, which further proved the adsorption of Fe2+ was major in inner sphere complexation and the adsorption of S2- was major in outer complexation. The desorption rates of Fe2+ and S2- which was adsorbed by fermented rice husk were lower in different pH or ionic strength conditions, the desorption rates were all below 10 percentage which proved that the adsorption stabilities of Fe2+ and S2- on fermented rice husk were superior. The above results indicated that, the adsorption abilities to Fe2+ and S2- on fermented rice husk were better and had greater environmental adaptability. The Fe2+ and S2- adsorbed by fermented rice husk showed higher stability, and were not easy to release again.

[Wastewater pollution characteristics from typical intensive pig farms in the Pearl River Delta and its ecological risk assessment].

Based on the wastewater quality investigation data from March 2009 to November 2011, wastewater qualities from typical intensive pig farms were assessed in the Pearl River Delta by single and comprehensive pollution index model. The results showed that key pollutants of piggery wastewater were fecal coliform (FC), total phosphorus (TP), chemical oxygen demand (COD) and biochemical oxygen demand (BOD), with their average mass concentrations of 1.98 x 10(9) CFU.L-1, 158.61 mg.L-1, 5 608.68 mg.L-1 and 1984.34 mg.L-1, respectively; key pollutants of biogas slurry were FC, TP, ammonia nitrogen (NH+4 -N) and suspended substance (SS), with their average mass concentrations of 8. 10 x 10(6) CFU.L-1, 81.76 mg.L-1, 476.24 mg.L-1 and 464.58 mg.L-1, respectively. Under the effect of wastewater pollutants, environment surrounding of typical intensive pig farms was seriously polluted, which decreased gradually from piggery wastewater to biogas slurry, and comprehensive pollution indices were 11.41, 6.91, 5.27, respectively. The risk analysis showed that the high-risk wastewater could never be discharged directly and irrigated crops. After the anaerobic treatment, FC, TP, NH+4 -N and SS were still strong factors with the potential ecological risk in the biogas slurry. In the long run, the ecological risk still exists for direct discharge or irrigation of them, and it is necessary to apply further treatment.

Evolution of microbial community diversity and enzymatic activity during composting.

The composting of organic material is dependent on microbial activity. However, the dynamics of the microbial community during the composting process remain obscure. Here, denaturing gradient gel electrophoresis of 16S rDNA amplicons in a chicken manure-based compost was applied to characterize the components of the microbial community during the composting process. In addition, the activity of key microbial enzymes was monitored. Arcobacter spp. and Marinospirillum spp. were the dominant species prior to composting, whereas Thermotogae spp. became more strongly represented as the composting process proceeded. Bacillus and Cohnella spp. were featured at various phases. Correlation analysis showed that the diversity of the microbial community was positively correlated with the compost pH, its total nitrogen level, its carbon-to-nitrogen ratio and the activity of protease, and negatively correlated with its organic carbon content and seed germination indices.

[Screening of two straw-cellulose degrading actinomycetes].

OBJECTIVE: The aim of this study was to screen microorganisms that could degrade rice straw. METHODS: We used selective medium to screen strains and determined straw fracture tension strength, weight loss, lignocellulose decomposition rate and extracellular enzyme activity as re-screening methods after 10 days shake flask culture. RESULTS: We isolated two antinomycetes (A3 and A6), the highest cellulose enzyme activity of holoenzyme, beta3-Glucosidase, endonuclease and exonclease for A3 were 12.84, 6.23, 24.56 and 14.00 U/mL, and for A6 12.85, 6.53, 17.80 and 18.80 U/mL. The hemicelluloses enzyme activity was 83.05 for A3 and 52.98 U/mL for A6. Both strains belonged to Streptomyces. With 10 days' treatment, inoculated straws showed a decrease of straw fracture tension strength by 62.67% (A3) and 66.67% (A6), while weight loss of straw was 31.50% (A3) and 35.83% (A6). A3's decomposition rate of cellulose, hemicellulose and lignin was 38.73% , 33.16% and 20.68% , and 47.69% , 28.64% and 22.59% for A6. CONCLUSION: Antinomycetes A3 and A6 could degrad cellulose, hemicellulose and lignin.

The addition of modified attapulgite reduces the emission of nitrous oxide and ammonia from aerobically composted chicken manure.

UNLABELLED: The acceleration of the composting process and the improvement of compost quality have been explored by evaluating the efficacy of various additives, inoculating with specific microorganisms and the application of various biosurfactants. The magnesium-aluminum silicate attapulgite is a low-cost potential composting additive, but its effects on aerobic composting are unknown. This study investigated the effects of attapulgite application on compost production and quality during the aerobic composting of chicken manure. Addition of attapulgite significantly increased the temperature (p < 0.05) while it reduced compost total organic carbon (TOC) and seed germination indices (GIs) throughout the process. Its addition enhanced nitrate concentrations, promoted organic matter degradation, increased seed germination indices, and accelerated the composting process. Interestingly, attapulgite addition did not increase the population of ammonia-oxidizing bacteria. These results suggest that attapulgite is a good additive for the composting industry. IMPLICATIONS: We investigated the addition of two forms of attapulgite during aerobic composting of chicken manure to determine their effects under strict composting environmental parameter control. Our results provides primary evidence that attapulgite may have potential for application in the composting industry. All treatments showed no increase within the first 15 days. However, emissions increased for all treatments within 15-45 days, reaching approximately 6300, 2000, and 4000 mg/m2 from the control, artifactitious attapulgite, and raw attapulgite treatments, respectively.

Improved composting of poultry feces via supplementation with ammonia oxidizing archaea.

Ammonia-oxidizing archaea (AOA) play an important role in the oxidation of ammonia. However, the participation of AOA in the composting process has not been established. The addition of AOA to a compost mix was able to speed up both the onset of the hyperthermic phase and the composting time. The composition of the microflora and the relative abundance were determined by using denaturing gradient gel electrophoresis and quantitative real-time PCR, based on the presence of the archaeal amoA genes. The amplicon profiles allowed some of the major AOA species present in the final compost to be identified, and their relative abundance to be estimated from their amplification intensity. The lower pH during the lower temperature phase of compost served to enhance the nitrogen content of the final compost. The addition of AOA resulted in the expanding diversity of microflora species than that of the natural colonization.

[Screening and identification of hemicellulose degrading microorganisms in acid soil].

OBJECTIVE: The aim of this study was to screen hemicellulose degrading microorganisms. METHODS: The methods used to screen the effective strains included hydrolysis spot diameter measurement of hemicellulose plate and extracellular enzyme activity. The methods used to identify the strains included culture characteristics, morphological, physiological-biochemical characteristics and molecular biological methods. RESULTS: We isolated 4 actinomycetes (NA9, NA10, NA12 and NA13), 2 fungi (NF1 and NF7) with hemicellulose degrading ability and no antagonistic effect among them. The hemicellulose degrading activity of 4 actinomyces (NA9, NA10, NA12 and NA13) was 217.6, 229.8, 221.1 and 211.8 U/mL. The hemicellulose degrading activity of 2 fungi (NF1 and NF7) was 217.7 and 244.2 U/mL. The hemicellulose degrading activity of complex microbial system was 299.0 U/mL. NA9, NA10, NA12 and NA13 were Streptomyces costaricanus; NF1 was Aspergillus candidus and NF7 was Tarlaromyces flavus. CONCLUSION: the 4 actinomyces and 2 fungi screened have high hemicelluloses enzyme activity. These strains have good application value and more research value.

Preparation of a modified flue gas desulphurization residue and its effect on pot sorghum growth and acidic soil amelioration.

A modified flue gas desulphurization residue (MFGDR) was prepared and its effects on sorghum growth and acidic soil amelioration were evaluated in this paper. The MFGDR was prepared by calcining a mixture of dry/semi-dry flue gas desulphurization (FGD) residue from a coal-fired power plant, sorted potash feldspar and/or limestone powder. The available nutrients from the MFGDR were determined with 4.91 wt% K(+), 1.15 wt% Mg(2+), 22.4 wt% Ca(2+), 7.01 wt% Si(4+) and 2.07 wt% SO(4)(2-)-S in 0.1 mol L(-1) citric acid solution. Its pH value was held at 9.60 displaying slightly alkaline. The results of sorghum pot growth in both red and crimson acidic soil for 30 days indicated that adding the MFGDR at a dosage of 2 g kg(-1) in total soil weight would increase the growth rate of biomass by 24.3-149% (wet weight basis) and 47.3-157% (dry weight), the stem length and thickness increase by 5.75-22.1% and 4.76-30.9% in contrast with CK treatment for two test cuttings, respectively. The effect on sorghum growth was attributed to the increase of available nutrients, the enhancement of soil pH value and the reduction of aluminum toxicity in acidic soil due to the addition of the MFGDR. The experimental results also suggested that the MFGDR could be effectively used to ameliorate the acidic soil which is widely distributed throughout the southern China.

Effects of sulphur and Thiobacillus thioparus on cow manure aerobic composting.

A simulated aerobic composting experiment was used to explore the effects of sulphur and Thiobacillus thioparus during six manure composting treatments. The addition of sulphur led to a decrease of the pH level within the range 6-6.3, which was lower than the control treatment (CK). The concentration of ammonium nitrogen in T1 (0.25% sulphur), T2 (0.5% sulphur), T3 (0.25% sulphur + T. thioparus) and T4 (0.5% sulphur + T. thioparus) were much higher than the ammonium N in CK. The results indicated that addition of sulphur could increase the concentration of ammonium N and reduce loss of nitrogen. However, excess sulphur had a negative effect on temperature and GI. Addition of T. thioparus could increase concentration of available S, alleviate these negative influences and reduce compost biological toxicity.

Effects of alkyl polyglycoside (APG) on composting of agricultural wastes.

Composting is the biological degradation and transformation of organic materials under controlled conditions to promote aerobic decomposition. To find effective ways to accelerate composting and improve compost quality, numerous methods including additive addition, inoculation of microorganisms, and the use of biosurfactants have been explored. Studies have shown that biosurfactant addition provides more favorable conditions for microorganism growth, thereby accelerating the composting process. However, biosurfactants have limited applications because they are expensive and their use in composting and microbial fertilizers is prohibited. Meanwhile, alkyl polyglycoside (APG) is considered a "green" surfactant. This study aims to determine whether APG addition into a compost reaction vessel during 28-day composting can enhance the organic matter degradation and composting process of dairy manure. Samples were periodically taken from different reactor depths at 0, 3, 5, 7, 14, 21, and 28 days. pH levels, electrical conductivity (EC), ammonium and nitrate nitrogen, seed germination indices, and microbial population were determined. Organic matter and total nitrogen were also measured. Compared with the untreated control, the sample with APG exhibited slightly increased microbial populations, such as bacteria, fungi, and actinomycetes. APG addition increased temperatures without substantially affecting compost pH and EC throughout the process. After 28 days, APG addition increased nitrate nitrogen concentrations, promoted matter degradation, and increased seed germination indices. The results of this study suggest that the addition of APG provides more favorable conditions for microorganism growth, slightly enhancing organic matter decomposition and accelerating the composting process, improving the compost quality to a certain extent.