Background: Apple trees are often subject to severe salt stress in China as well as in the world that results in significant loss of apple production. Therefore this study was carried out to evaluate the response of apple seedlings inoculated with abuscular mycorrhizal fungi under 0, 2‰, 4‰ and 6‰ salinity stress levels and further to conclude the upper threshold of mycorrhizal salinity tolerance. Results: The results shows that abuscular mycorrhizal fungi significantly increased the root length colonization of mycorrhizal apple plants with exposure time period to 0, 2‰ and 4‰ salinity levels as compared to non-mycorrhizal plants, however, percent root colonization reduced as saline stress increased. Salinity levels were found to negatively correlate with leaf relative turgidity, osmotic potential irrespective of non-mycorrhizal and mycorrhizal apple plants, but the decreased mycorrhizal leaf turgidity maintained relative normal values at 2‰ and 4‰ salt concentrations. Under salt stress condition, Cl⁻ and Na⁺ concentrations clearly increased and K⁺ contents obviously decreased in non-mycorrhizal roots in comparison to mycorrhizal plants, this caused mycorrhizal plants had a relatively higher K⁺/Na⁺ ratio in root. In contrast to zero salinity level, although ascorbate peroxidase and catalase activities in non-inoculated and inoculated leaf improved under all saline levels, the extent of which these enzymes increased was greater in mycorrhizal than in non-mycorrhizal plants. The numbers of survived tree with non-mycorrhization were 40, 20 and 0 (i.e., 66.7%, 33.3% and 0) on the days of 30, 60 and 90 under 4‰ salinity, similarly in mycorrhization under 6‰ salinity 40, 30 and 0 (i.e., 66.7%, 50% and 0) respectively. Conclusion: These results suggest that 2‰ and 4‰ salt concentrations may be the upper thresholds of salinity tolerance in non-mycorrhizal and mycorrhizal apple plants, respectively.

This study investigated the effects of biochar, fly ash, and biomass power plant ash on ammonia–nitrogen (NH ₃ ) emission reduction and nitrogen retention during aerobic composting (AC) of chicken manure and corn straw. In detail, 9 groups treated with different proportions (4, 8, and 12%) of additives (biochar, fly ash, and biomass power plant ash) were designed through 21-day AC experiments. Further, the impacts of different temperatures (20, 40, and 60 °C) on nitrogen emission were explored and analyzed. Results showed that 8% biochar (T _1-2 ) reduced total NH ₃ emission by 54.83% and peak emission by 70.26%, while increasing final total nitrogen by 22.40% versus the control. At the same time, it significantly increases the content of nitrate nitrogen and optimizes the nitrogen-transformation efficiency. Fly ash (T _2-2 ) and biomass power plant ash (T₃-₁) achieved 35.61 and 42.34% inhibition rates, respectively. Temperature experiments revealed optimal NH ₃ suppression at 20 °C (T20), while 60 °C (T60) enhanced total nitrogen by 39.8% and organic matter degradation by 30.91%. Excessive additive proportions (12%) prolonged high-temperature phases, diminishing efficacy. The optimal strategy combines 8% biochar addition at 20 °C (initial stage) to mitigate NH ₃ volatilization, followed by maintaining 60 °C to ensure composting efficiency and nitrogen retention. This approach balances emission reduction and nutrient conservation in AC processes.

Developing a green and sustainable method to upgrade biogas wastes into high value-added products is attracting more and more public attention. The application of solid residues as a performance enhancer in the manufacture of biofilms is a prospective way to replace conventional plastic based on fossil fuel. In this work, solid digestates from the anaerobic digestion of agricultural wastes, such as straw, cattle and chicken manures, were pretreated by an ultrasonic thermo-alkaline treatment to remove the nonfunctional compositions and then incorporated in plasticized starch paste to prepare mulching biofilms by the solution casting method. The results indicated that solid digestate particles dispersed homogenously in the starch matrix and gradually aggregated under the action of a hydrogen bond, leading to a transformation of the composites to a high crystalline structure. Consequently, the composite biofilm showed a higher tensile strength, elastic modulus, glass transition temperature and degradation temperature compared to the pure starch-based film. The light, water and GHG (greenhouse gas) barrier properties of the biofilm were also reinforced by the addition of solid digestates, performing well in sustaining the soil quality and minimizing N₂O or CH₄ emissions. As such, recycling solid digestates into a biodegradable plastic substitute not only creates a new business opportunity by producing high-performance biofilms but also reduces the environmental risk caused by biogas waste and plastics pollution.

A study was designed aiming at the degradation of organic matter in liquid phase of pig manure, the inactivation of pathogenic microorganisms and biogas production at different storage temperatures. A low cost rapid anaerobic fermentation, and biogas sewage storage system was constructed. After the four-day anaerobic fermentation, three treatments were set up: the average temperature of spring and autumn (16.1ºC), summer (25ºC), and winter (0.6ºC) in Yantai City was used as storage temperature for 90 days, respectively. The results showed that the biogas potential of anaerobic fermentation and biogas sewage storage at 16.1ºC and 25ºC was higher than that stored at 0.6ºC. During the experiment, total solids (TS) and organic matter contents in fecal sewage were decreased with time, and the value was determined at 25ºC. Total phosphorus and potassium contents in biogas sewage did not change significantly over time, but the total nitrogen content decreased. The content of the 5 day biological oxygen demand (BOD5), the chemical oxygen demand (CODCr) and suspended solid concentration (SS) in fecal sewage showed a downward trend over time. The egg mortality of Ascaris lumbricoides increased in different degrees under the three storage conditions. The number of E. coli in biogas sewage stored at 0.6ºC and 16.1ºC showed a downward trend, and the number of E. coli in biogas sewage stored at 25ºC was significantly higher than at 0.6ºC and 16.1ºC. The comprehensive analysis showed that at temperature 25ºC, the an-aerobically produced fecal sewage after fermentation had best potential for biogas production.

Present research reveals the effect of different soil environment modifications on population dynamic tendency of fecal Escherichia coli (E. coli). Various soil environments were created by varying the temperature regimes, relative water content, pH, C/N ratio and ammonium content. The result showed that population dynamics of E. coli with all treatments increased initially and then decreased with the passage of time. Maximum population of E. coli at higher temperature regime (37ºC and 45ºC) was observed on 8th day of incubation, whereas, at low temperature regime (0.6ºC and 25ºC), it reached the peak after 15 days of incubation, other treatments (soil relative water content, pH, C/N, ammonium content) reached the peak all after 8 days of incubation. At the end of the incubation period (60 days), maximum population of E. coli was observed in the soil treated with 0.6ºC, 80% of relative soil water content, pH 7.0, 135 mg-ammonium/kg and C/N of 25:1. The results indicated that 45ºC, 90% of relative water content, pH 9.0, 125 mg-ammonium/kg, C/N of 10:1 inhibited E. coli growth, whereas, 37ºC, 80% of relative soil water content, pH 7.0, 135 mg-ammonium/kg and C/N of 25:1 stimulated E. coli growth.

This study was conducted to evaluate the effects of plant ash based ammonia stripping process on removal and recovery of ammonia-nitrogen (NH3-N) in biogas slurry (BS), in order to provide theoretical reference for the feasibility of plant ash, as replacement of sodium hydroxide. The best mixing ratio of plant Ash and biogas slurry, gas-liquid ratio, stripping time and stripping temperature was also determined to optimize the process. The results showed that the (NH3-N) removal rate was 85.27% and the recovery rate was 76.45%, at 10:2 biogas slurry and plant ash mixing ratio, the gas-liquid ratio of 2000, the stripping temperature of 30ºC and the stripping time of 2 h. Compared with sodium hydroxide as stripping promoter the removal rate and recovery rate of ammonia nitrogen in biogas slurry were increased by 4.15% and 6.49% respectively, and the operation cost of ammonia nitrogen stripping process was reduced by plant ash replacing sodium hydroxide. The comprehensive analysis suggested that it is feasible to combine the plant ash with biogas slurry to remove ammonia nitrogen.