Reduce Nitrogen Losses Research Articles

Promoting role of nitrogen-fixing bacteria and biochar on nitrogen retention and degradation of PBAT plastics during composting.

Since the increasing number of polybutylene adipate terephthalate (PBAT)-based plastics entering the environment, the search for sustainable treatment methods has become a primary focus of contemporary research. Composting offers a novel approach for managing biodegradable plastics. However, a significant challenge in the composting process is how to control nitrogen loss and enhance plastic degradation. In this context, the effect of various additives on nitrogen retention, PBAT plastics degradation, and microbial community dynamics during composting was investigated. The findings revealed that the addition of nitrogen-fixing bacteria Azotobacter vinelandii and biochar (AzBC) significantly improved nitrogen retention and accelerated PBAT rupture within 40 days of composting. Specifically, the PBAT degradation rate in the AzBC group reached 29.6%, which increased by 12.14% (P<0.05) compared to the control group. In addition, the total nitrogen (TN) content increased by 6.20% (P<0.05), and the Nitrogen-fixing enzyme (NIT) content increased by 190 IU/L (P<0.05). Further analysis of GC-MS confirmed the presence of low molecular weight fragmentation products, such as 6-(4-hydroxybutoxy)-6-oxohexanoic acid. The AzBC treatment promoted the proliferation of Klebsiella at the genus level that could enhance nitrogen retention and the bacteria that have the ability to degrade PBAT, such as Proteobacteria and Firmicutes at the phyla level, and Pseudoxanthomonas, Pseudomonas, and Flavobacterium genera at the genera level (P<0.05). Correlation analysis indicated that the degradation of PBAT is positively correlated with Temperature (T), NIT, and TN, but negatively correlated with the organic matter (OM) content and germination index (GI). In conclusion, the co-application of biochar and Azotobacter vinelandii offers promising sustainable prospects for enhancing PBAT plastic degradation and reducing nitrogen loss during composting.

Simulating Agricultural Water Recycling Using the APEX Model

Irrigation plays a vital role in many agricultural crop production regions. Drainage water recycling (DWR) is a popular irrigation water management system that collects excess water drained from cropland fields and stores it in on-site reservoirs for reuse. The efficacy of these systems varies by location, climate, irrigation frequency, and crop demands. Simulating this system would be beneficial for assessing the impact of water and land management practices on agriculture and natural resources. This study presents the development of computational algorithms for DWR simulation with the Agricultural Policy Environmental eXtender (APEX) model, along with the results for 39 testing sites where both reservoir and drainage systems are adopted. Simulating a DWR system with the revised reservoir module, the APEX model simulates irrigation water reuse ranging between 29% and 93%; sediment reduction of around 66%; nitrogen loss reduction of 23% and 73% for the mineral and organic forms, respectively; and phosphorus loss reduction of 22% and 79% for the soluble and sediment-transported forms, respectively. In conclusion, the results provided by the APEX model for sediment loss reduction align with field data, but discrepancies for nitrogen and phosphorus losses emerged from this test.

Impact of low crude protein diets containing animal byproducts on growth performance, nitrogen excretion, meat yield and quality in broiler chickens

This study examined the impact of a low crude protein (CP) diet incorporating meat and bone meal (MBM) as an alternative (AD) to standard diet, on broiler performance, nitrogen intake, excretion, and meat quality. A total of 846 male Ross 308 chicks were assigned to two diets in a randomized complete block design with 9 replicates of 47 birds/replicate. The diets were a plant-based control (20.4 and 19.5% CP) and an AD diet (-2.0% CP, +2.5% MBM) in the grower and finisher phases. Compared to the control, the AD diet reduced nitrogen intake (P = 0.01) and excretion (P &lt; 0.01) while improving nitrogen retention efficiency (P &lt; 0.001) without affecting body weight, feed conversion, or carcass yield. Breast yield was higher in the AD group (P &lt; 0.001). In the AD group, the ultimate pH of breast meat increased slightly (P = 0.07), cooking loss decreased (P = 0.002), sarcoplasmic protein solubility tended to increase (P = 0.09), while muscle protein emulsifying properties remained unchanged. Breast meat proximate composition was not affected by the AD diet. In conclusion, the AD diet can reduce nitrogen loss and emissions without negatively impacting broiler production, provided that amino acid requirements are met.

Application of Nitrate–Ammonium Nitrogen Fertilization Reduced Nitrogen Loss in Surface Runoff and Infiltration by Improving Root Morphology of Flue-Cured Tobacco

Nitrogen loss in water from farmland has become an environmental issue. Nitrogen fertilizer is the main cause of agricultural non-point source pollution in the Lake Basin, Yunnan. However, it is unclear how different nitrogen fertilizer forms affect water loss from farmland and how the root systems of crops respond. We established five nitrogen fertilizer treatments (100–0% [T1], 75–25% [T2], 50–50% [T3], 25–75% [T4], and 0–100% [(T5)] nitrate–ammonium) and performed an investigation to determine nitrogen loss in water and root morphological parameters of tobacco in Mile County and Chengjiang County. Compared with in the T1, T4, and T5 treatments, the total nitrogen loss in surface runoff was reduced by 4.67%, 11.85% and 9.56% in the T2 treatment and 27.32%, 23.20%, and 31.43% in the T3 treatment, respectively. Similar results were observed for the nitrogen loss due to infiltration. The root biomass was negatively correlated with nitrogen loss. There was greater root biomass, root surface area, and root spatial distribution in T2 and T3 compared with in T1, T4, and T5. These results indicate that 50–50% nitrate–ammonium nitrogen fertilizer can facilitate the root growth of tobacco and reduce nitrogen loss, which provides a reference for agricultural sustainable development.

Assessment of Nitrogen Volatilization and Greenhouse Gas Emissions from Urea with N-stabilizer in a Productive Oil Palm Plantation (Elaeis guineensis Jacq.)

Nitrogen fertilization plays a crucial role in supporting plant growth. However, nitrogen in the soil can be lost through rainwater leaching. To address this issue, the concept of fertilizing N-stabilizer-coated urea was proposed. The aim is to reduce nitrogen loss on the field due to vaporization and minimize greenhouse gas (GHG) emissions. The study was conducted to assess the effectiveness of this N-stabilizer-coated urea in reducing nitrogen loss through vaporization, improving GHG emissions, and its impact on plant growth and leaf quality. The research was conducted at IPB-Cargill Jonggol, Bogor, West Java, oil palm education and research station from August 2021 to March 2022. The experimental design employed a completely randomized block design. The fertilizer treatments included four types of nitrogen fertilizers: urea (46% N), coated urea with N-stabilizer (46% N), ZA (21% N), and NPK (15-15-15, 15% N). Additionally, a control treatment without any fertilizer application was included. All treatments were replicated three times. Data analysis was done using the SAS (Statistical Analysis System) 9.0 program. The F-test was conducted, followed by DMRT (Duncan Multiple Range Test) advanced tests at a 5% error level. The results revealed that urea with N-stabilizer fertilization significantly reduced NH3-vaporization by 53% in the first week compared to the application of normal urea. NH3-vaporization level from ZA and NPK was &lt; 1% compared to urea application. Field application of urea with N-stabilizer showed no significant difference in greenhouse gas emission (GHG) compared to the other nitrogen fertilizer types. The GHG values ranged from 7.10 to 7.29 g CO2-e.m-2 per day. The use of N-stabilizer-coated urea could be an effective approach to minimize nitrogen loss through vaporization and reduce greenhouse gas emissions while maintaining comparable results to other nitrogen fertilizer types in terms of GHG emissions on the field.

Effect of mineral additives and ammonia-oxidizing bacteria additions on physicochemical properties, nitrogen retention and microbial dynamics during vermicomposting of chicken manure and green waste

Vermicomposting is an effective technology to transform organic wastes into organic fertilizers. However, a large amount of nitrogen will be lost through ammonia (NH3) volatilization during verimicomposting. Herein, we investigated the effects of mineral additives (diatomite, zeolite) and exogenous ammonia-oxidizing bacteria (AOB) (Nitrosomonas europaea, Nitrosospira multiformis) added individually or combinedly on the physicochemical changes, the conversion of nitrogen, and the resident microbial community succession during chicken manure and green waste co-vermicomposting. The results showed that the combined addition of AOB and mineral additives significantly improved vermicompost quality and maturity in terms of humus, carbon/nitrogen ratio, humic acid/fulvic acid ratio and germination index. Compared with the control, jointly adding AOB and mineral additives reduced NH3 emissions by 65.72∼71.05 %, accelerated the conversion of NH4+-N to NO3−-N, increased total nitrogen content by 23.22∼25.21 %. The combination of AOB and mineral additives significantly increased the activities of ammonia monooxygenase, hydroxylamine oxidase, and nitrate oxidoreductase, and enhanced the amount of AOB community. Additionally, the combined addition of AOB and mineral additives increased bacterial richness and diversity, accompanied by increased relative abundances of Luteimonas, Cellvibrio, Saccharimonadales, and Pseudomonas. These microbial shifts were correlated with enhanced lignocellulose degradation, organic phosphate mineralization, and promotion of plant growth. Moreover, vermiompost-based growing media with mineral additives and AOB can significantly promote the growth of purple cabbage as compared to the vermicompost without additives. Overall, the synergistic use of AOB and mineral additives (diatomite, zeolite) was recommended as a favorable approach for reducing nitrogen losses and improving the efficiency of chicken manure and green waste vermicomposting. This study offers a novel approach to mediate nitrogen transformation processes and reduce nitrogen loss.

SiO2 nanoparticles can enhance nitrogen retention and reduce copper resistance genes during aerobic composting of swine manure

SiO2 nanoparticles (SiO2 NPs) are low-cost, environmentally friendly materials with significant potential to remove pollutants from complex environments. In this study, SiO2 NPs were used for the first time as an additive in aerobic composting to enhance nitrogen retention and reduce the expression of copper resistance genes. The addition of 0.5 g kg−1 SiO2 NPs effectively reduced nitrogen loss by 72.33 % by decreasing denitrification genes (nosZ, nirK, and napA) and increasing nitrogen fixation gene (nifH). The dominant factors affecting nitrification and denitrification genes were Firmicutes and C/N ratio. Additionally, SiO2 NPs decreased copper resistance genes by 28.96 % − 37.52 % in compost products. Copper resistance genes decreased most in the treatment with 0.5 g kg−1 SiO2 NPs. In summary, 0.5 g kg−1 SiO2 NPs have the potential to reduce copper resistance genes and enhance nitrogen retention during aerobic composting, which may be used to improve compost quality.

Distribution of Non-Structural Carbohydrates and Root Structure of Plantago lanceolata L. under Different Defoliation Frequencies and Intensities.

Plantago lanceolata L. (plantain) increases herbage dry matter (DM) production and quality during warm and dry conditions due to its deep roots and drought tolerance and reduces nitrogen losses in grazing systems compared to traditional pastures. However, plantain density usually declines after the third growing season, mainly due to defoliation management. The effects of defoliation frequency and intensity on water-soluble carbohydrate (WSC) reserves and below-ground plant responses need further research to optimize grazing strategies for improved productivity and sustainability of grazing systems. Our study investigated the effects of defoliation frequencies (15, 25, and 35 cm of extended leaf length, ELL) and intensities (5 and 8 cm of residual heights) on morphological traits and WSC concentrations in plantain biomass under controlled environmental conditions. Defoliation frequency significantly influenced morphological and chemical characteristics and biomass distribution more than residual height. Less frequent defoliations promoted above-ground herbage DM production, reproductive stems, and root biomass. Root architecture showed adaptations in response to defoliation frequency, optimizing resource acquisition efficiency. Frequent defoliation reduced high molecular weight WSC concentrations in leaves, affecting regrowth capacity and DM mass. A defoliation frequency of 25 cm ELL (~15 days) balances herbage production and root development, promoting long-term pasture sustainability.

Extended photoperiods enhance the production and water treatment performance of algal-bacterial bioflocs from aquaculture wastewater

Reducing pollution and converting wastewater nutrients into useful biomass are major challenges of intensive aquaculture. We investigated the nitrogen and phosphorus metabolism, nutrient composition, and microbial community of algal-bacterial bioflocs (ABBs) produced under glucose addition and different photoperiods. This biomass was used for aquaculture wastewater treatment for 18 days. ABBs produced under longer photoperiods were smaller and more numerous, which facilitated nitrogen recovery and reduced nitrogen loss. Additionally, nitrogen and phosphorus-metabolizing enzyme activities, as well as the activity of overall microorganisms were positively correlated with the light duration. The removal rates of COD (96.89 %), DTN (93.57 %), and DTP (93.67 %) from wastewater by ABBs were highest when the photoperiod was 16L:8D during the production period. Moreover, the crude protein content (41.77 ± 0.11 %) was highest under a photoperiod of 12L:12D, and the rich amino acid and fatty acid profile of the ABB under this photoperiod enhanced its utility as a feed additive for aquaculture species. The high-throughput sequencing analysis revealed a high abundance of Hydrogenophaga at the genus level, highlighting its denitrification capacity of ABBs under the 16L:8D photoperiod. Redundancy analysis (RDA) demonstrated that photoperiod, as a key driver in the formation of microbial communities in ABBs, exerted a direct influence on water treatment efficiency and nutrient accumulation. This study provides new insights into the effects of photoperiod on the properties of ABBs, which has implications for the treatment and subsequent application of aquaculture wastewater.

Innovative approach for assessing nitrogen loss risk to surface waters from crop production in a watershed scale through nitrogen surplus index method

Although various measures are applied to control farmland nitrogen loss at the field scale, effective control strategies at the watershed scale are still lacking due to poor understanding of nitrogen loss risks across different scales. Therefore, an innovative approach to assess the risk of nitrogen loss to surface waters from crop production at the watershed scale was established, with nitrogen surplus, a more accurate indicator, as a major source factor introduced to the traditional index method. Furthermore, this approach was applied in the Baiyangdian Lake Watershed, a typically agricultural-dominated watershed in China, and the control strategies for farmland nitrogen loss reduction were investigated with scenario analysis. The major results included: (1) Areas with high (2–4 for risk to river, 1.6–3.2 for risk to lake) and very high (>4 for risk to river, >3.2 for risk to lake) risks of nitrogen loss in crop production were relatively small. For example, in the wheat-maize rotation system, these areas accounted for only 2.1–3.5 % and 0.9–1.8% of the total study area, respectively. Additionally, the critical source areas of nitrogen loss were concentrated around the receiving water bodies. (2) The nitrogen surplus in wheat season increased the nitrogen loss to surface waters. Compared to the maize season, the area with high and very high risk for nitrogen loss to the nearby river in wheat-maize rotation system increased by 58.3% and 141.4%. Furthermore, the areas with high and very high risk for nitrogen loss to the lake in wheat-maize rotation system were 129.6% and 220.6% more than that during maize season. (3) Nitrogen loss risk to the nearby rivers was correlated with nitrogen surplus, but nitrogen loss risk to the lake was related to the transport coefficient. (4) The optimized scenario for nitrogen loss reduction in crop production was the combination of nitrogen surplus being less than 20 kg/ha and 500 m banning area around the river with no fertilizer application, which reduced the nitrogen loss risk to the nearby river and to the lake by 94–95% and 89–95%. The results of this study provide a scientific basis for nutrient resource management and non-point source pollution control.

Synergistic effects of biochar and laccase on nitrogen conversation and degradations of two artificial sweeteners during the sewage sludge composting

This study investigates the effects of biochar, laccase, and their combined application on nitrogen transformation, the degradation of sucralose (SUC) and acesulfame (ACE), and the dynamics of bacterial communities during sewage sludge composting. The results indicated that NH3 emissions were reduced by 41.2 %, 17.5%, and 40.8 % in the biochar, laccase, and biochar-laccase treatments, respectively, compared to the control. Meanwhile, N2O emissions decreased significantly by 26.8 % and 16.0 % for the biochar and biochar-laccase treatments, respectively, but increased by 8.1 % for the laccase treatment. Additionally, the biochar, laccase, and biochar-laccase treatments enhanced the degradation of SUC and ACE by 36.6–68.3 % and 49.2–69.8 %, relative to the control, respectively. Network analysis showed that the additive-treatment enhanced the cooperation within bacterial communities, and solidified artificial sweeteners degradation, especially under biochar-laccase application. Phylogenetic investigation of communities by reconstruction of unobserved states further indicated that biochar, laccase, biochar-laccase treatment increased enzymes associated with the degradations of organic matter and artificial sweeteners. In conclusion, it suggested that a combined addition of biochar and laccase was an effectively way to reduce nitrogen loss and promote artificial sweeteners degradations during sewage sludge composting.

Effect of feeding time and time of harvest of fresh pasture on urinary and faecal nitrogen excretion patterns in sheep

ABSTRACT Under New Zealand grazing systems, a high proportion of the nitrogen consumed by ruminants is excreted. This experiment examined the effect of feeding morning and afternoon harvested annual ryegrass, fed shortly after harvest, on the timing of nitrogen excretion in one-year-old sheep during winter. Dry matter and water-soluble carbohydrate (WSC) content increased in the afternoon-harvested ryegrass. This resulted in increased protein and WSC intakes and a decrease in nitrogen loss in the sheep fed in the afternoon with afternoon-harvested grass. The pattern of urinary nitrogen excretion was related to feeding time with peak urinary urea excretion in the period 4–8 hours after feeding, with over 60% of the daily urinary urea excreted in the 12 hours after the feed was offered. This study suggests that shifting stock onto new pasture breaks in the afternoon could reduce nitrous oxide production by increasing the efficiency of nitrogen utilisation in animals and reducing the total amount of nitrogen excreted. It may be possible to utilise the potential diurnal differences in pasture composition to reduce nitrogen losses. This practise could also improve animal performance as well as change the timing of nitrogen excretion.

Soil Factors Key to 3,4-Dimethylpyrazole Phosphate (DMPP) Efficacy: EC and SOC Dominate over Biotic Influences.

Nitrification inhibitors like 3,4-dimethylpyrazole phosphate (DMPP) are crucial in agriculture to reduce nitrogen losses. However, the efficacy of DMPP varies in different soils. This microcosm incubation study with six soils was conducted to elucidate how soil abiotic factors (physicochemical properties) and biotic factors (nitrogen-cycling microbial abundance and diversity) influence the performance of DMPP. The DMPP efficacy was evaluated through the ammonium-N retention rate (NH4+_RA), inhibition rate of net nitrification rate (NNR_IR), and reduction rate of N2O emissions (N2O_ERR). The results showed that DMPP had significantly different effects on mineral nitrogen conversion and N2O emissions from different soils. NH4+_RA, NNR_IR, and N2O_ERR ranged from -71.15% to 65.37%, 18.77% to 70.23%, and 7.93% to 82.51%, respectively. Correlation analyses and random forest revealed abiotic factors, particularly soil EC and SOC, as the primary determinants of DMPP efficiency compared to microbial diversity. This study sheds new light on the complex interactions between DMPP efficacy and soil environments. The identification of soil EC and SOC as the dominant factors influencing DMPP efficacy provides valuable insights for optimizing its application strategies in agricultural systems. Future research could explore the mechanisms underlying these interactions and develop tailored DMPP formulations that are responsive to specific soil conditions.

Effects of Paddy Rain-Flood Storage on Rice Growth Physiological Indices and Nitrogen Leaching under Organic Planting in Erhai Lake Basin.

In order to address the increasingly prominent issues of water resource protection and agricultural non-point source pollution in the Erhai Lake Basin, this study conducted a two-year field experiment in Gusheng Village, located in the Erhai Lake Basin. In 2022, two irrigation treatments were set up: conventional flooding irrigation (CK) and controlled irrigation (C), with three replicates for each treatment. In 2023, aiming to enhance the utilization rate of rainwater resources and reduce the direct discharge of dry-farming tailwater from upstream into Erhai Lake. The paddy field was used as an ecological storage basin, and the water storage depth of the paddy field was increased compared to the depth of 2022. Combined with the deep storage of rainwater, the dry-farming tailwater was recharged into the paddy field to reduce the drainage. In 2023, two water treatments, flooding irrigation with deep storage and controlled drainage (CKCD) and water-saving irrigation with deep storage and controlled drainage (CCD) were set up, and each treatment was set up with three replicates. The growth and physiological index of rice at various stages were observed. Nitrogen leaching of paddy field in surface water, soil water, and groundwater under different water treatments after tillering fertilizer were observed. The research results show that the combined application of organic and inorganic fertilizers under organic planting can provide more reasonable nutrient supply for rice, promote dry matter accumulation and other indices, and also reduce the concentration of NH4+-N in surface water. Compared with CK, the yield, 1000-grain weight, root-to-shoot ratio, and leaf area index of C are increased by 4.8%, 4.1%, 20.9%, and 9.7%, respectively. Compared with CKCD, the yield, 1000-grain weight, root-to-shoot ratio, and leaf area index of CCD are increased by 6.5%, 3.8%, 19.6%, and 21.9%, respectively. The yield in 2023 is 19% higher than that in 2022. Treatment C can increase the growth indicators and reduce the net photosynthetic rate to a certain extent, while CCD rain-flood storage can alleviate the inhibition of low irrigation lower limit on the net photosynthetic rate of rice. Both C and CCD can reduce nitrogen loss and irrigation amount in paddy fields. CCD can reduce the tailwater in the Gusheng area of the Erhai Lake Basin to Erhai Lake, and also can make full use of N, P, and other nutrients in the tailwater to promote the formation and development of rice. In conclusion, the paddy field rain-flood storage methodology in the Erhai Lake Basin can promote various growth and physiological indicators of rice, improve water resource utilization efficiency, reduce direct discharge of tailwater into Erhai Lake, and decrease the risk of agricultural non-point source pollution.

Development of eco-friendly modified natural and synthetic nanozeolites, for urea efficient delivery to vegetable plants with reducing nitrogen losses to environment

Development of eco-friendly modified natural and synthetic nanozeolites, for urea efficient delivery to vegetable plants with reducing nitrogen losses to environment

Soil application of activated hydrochar derived from sewage sludge enhances plant growth and reduces nitrogen loss

Sewage sludge treatment and disposal is a considerable environmental and economic burden, and is considered a major global challenge. Here, sewage sludge treatment and disposal were studied with a focus on hydrothermal carbonization and the use of hydrochar (HC) as a soil amendment after Fenton-reaction activation. The underlying hypothesis was that enhanced adsorption of nutrients (e.g., ammonium) by activated HC (AHC) increases their availability, thus enhancing plant growth and reducing environmental impacts such as greenhouse gas emission and N leaching relative to conventional soil-amendment techniques.The impact of AHC on lettuce plant growth, N leaching, ammonia volatilization, soil trace-gas emissions, and respiration was studied in a net-house planting experiment. Four treatments were tested in quadruplicate using sandy loam soil with addition of either AHC, urea fertilizer, or AHC plus urea, and a control with no amendment.Activation-induced changes in AHC surface properties (indicated by SEM and XPS analyses) resulted in an NH4+ adsorption capacity 60 % higher than that of untreated HC. The AHC + urea soil treatment yielded the most enhanced plant growth, followed by urea and AHC treatments with comparable growth rates. Least growth occurred in the control with no amendment. Nitrogen loss through gas emissions, per kg of lettuce, was lowest with AHC + urea treatment, although its mean N emission as nitrous oxide (N2O) was notably higher at 2.3 mg N2O-N kg−1 than for other treatments (∼0.4 mg N2O-N kg−1). Dissolved-N leaching was reduced by up to four times with AHC treatment due to its higher NH4+ adsorption capacity, indicating reduced environmental impact of the AHC amendment.AHC application is therefore considered a sustainable soil amendment, enhancing plant growth and reducing N loss and sewage environmental impact.

Humic Acids Combined with Dairy Slurry as Fertilizer Can Increase Alfalfa Yield and Reduce Nitrogen Losses

Dairy slurry could be a significant source of nitrogen (N) for plants, but mismanagement can lead to atmospheric ammonia losses or nitrate leaching into groundwater. To make the use of dairy slurry efficient and reasonable, the loss of N pollution to the environment should be reduced. We used repacked lysimeters to comprehensively determine ammonia emission and N leaching losses in an alfalfa–soil system. The application of dairy slurry had no significant effect on alfalfa yield at the same rate of N application in comparison to chemical fertilizer, and adding humic acids significantly increased yield by about 12%. However, the application of dairy slurry increased the ammonia emission rate significantly, leading to an increase in the cumulative amount of ammonia emission, while the addition of humic acids reduced the ammonia emissions by 11%. Chemical fertilizer and dairy slurry application significantly increased nitrate leaching compared to the control treatment, while the addition of humic acids can significantly reduce ammonium N leaching. Dairy slurry was proven to be as effective as chemical N fertilizer in achieving the optimum biomass, and adding humic acids can significantly reduce N loss to the atmosphere and groundwater. This study showed the possibility of replacing chemical fertilizer with dairy slurry in alfalfa production and the advantages of humic acids’ addition to alfalfa to maintain production yield and improve environmental friendliness.

Guidelines for efficient nitrogen preservation in sewage sludge-based fertilizers

This study explores sustainable methods to mitigate nitrogen (N) loss in agriculture amid rising food demands and limited arable land. It examines sewage sludge (SS) as an alternative to synthetic N fertilizers. SS is rich in nitrogen (4.21 ± 0.42 %) and phosphorus (3.60 ± 0.72 %), making it suitable for nutrient recovery and soil enhancement. Unfavorable sludge management methods result in the loss of 950,000 tons of nitrogen, meeting almost 10 % of the EU's nitrogen fertilization demand. This research evaluates SS treatment methods, including chemical conversion, thermal treatment, and biological composting, focusing on nitrogen conservation efficiency. Results show nitrogen loss during hydrolysis is minimized at pH 4 to 8 but increases significantly as ammonia (NH3) at pH 9 to 11, ranging from 4.2 % to 9 %. Neutralizing the hydrolysate is crucial; using solid KOH resulted in 13.5 % nitrogen loss, 11 times more than using slightly alkaline ash (1.22 %). Adding ash during drying reduced nitrogen emissions by 30 % compared to traditional drying at 105 °C. Improving the C/N ratio with food residues reduced nitrogen losses by 46.3 % during composting. These findings highlight the importance of pH control in chemical processes and temperature regulation in thermal treatments. Adding residues from other processes, such as biomass combustion waste, enhances SS processing conditions. Understanding nitrogen retention mechanisms is crucial for the environmental sustainability of SS usage. Efficient nitrogen retention strategies improve the fertilization value of SS and reduce its environmental footprint by lowering greenhouse gas emissions, particularly ammonia. Reducing nitrogen loss during SS treatment significantly lowers ammonia emissions, a major contributor to greenhouse gas emissions. These results help determine optimal methods for managing and processing SS to minimize emissions and increase agricultural usability.

Phosphate buffer‐driven precursor polycondensation to promote fermentative humification

AbstractBACKGROUNDAerobic fermentation always suffers from nitrogen loss and low humification degree. The objective of this study was to investigate the promotion of phosphate buffer on organic matter degradation and precursor polymerization into humus (HS) in aerobic fermentation, and to analyze the key roles played by different precursors. In order to achieve this, sludge aerobic fermentation tests were conducted on control (CK), phosphate buffer addition treatment (KP) and potassium chloride addition treatment (K).RESULTSThe HS content of KP treatment exhibited a notable increase compared to the CK and K treatments, with a maximum increase of 38.29%. In addition, phosphate addition improved the nitrogen retention capacity and the complexity of the HS structure. Phosphate buffer enhanced both the polyphenol and Maillard humification pathways by promoting the condensation of precursors (polysaccharides, reducing sugars, polyphenols, amino acids and proteins). Among these precursors, reducing sugars, amino acids and proteins were identified as the key driving precursors of phosphate.CONCLUSIONSPhosphate, as an exogenous additive to the fermentation system, reduces nitrogen loss while promoting precursor polymerization to form HS, which benefits the improvement of soil fertility and crop growth upon organic fertilizer application. © 2024 Society of Chemical Industry (SCI).

7. Reduction of dietary protein content and electrolyte balance to reduce nitrogen losses in broiler chickens

7. Reduction of dietary protein content and electrolyte balance to reduce nitrogen losses in broiler chickens