Search Results (170)

Researchers increasingly agree that livestock farming is the leading cause of air pollution with ammonia (NH₃) gas. The existing research suggests that 30–80% of nitrogen is lost from slurry and liquid manure in the gaseous form of ammonia. Most studies have focused on environmental factors influencing ammonia volatilization and manure composition but not on controlling the moisture level on the surface of the excreta. Applying the principles of convective mass exchange, this study was undertaken to compare different types of organic covers that mitigate NH₃ emissions and offer recommendations on how to properly apply organic covers on the surface of manure. Data was obtained from research in laboratory conditions comparing well-known coatings (chopped straw) with less commonly used organic materials (peat) or waste generated in other industries (sawdust, hemp chaff). This research demonstrated that applying bio-coatings can reduce ammonia (NH₃) emissions at coating thicknesses of ≥5 cm for sawdust, ≥3 cm for peat, ≥10 cm for hemp chaff, and 8–12 cm for straw. These reductions are linked to the ability of the coatings to lower manure surface moisture evaporation, a key driver of ammonia volatilization, highlighting the role of surface moisture control in emission mitigation. Full article

Inland saline wetlands in the Ebro Basin (Spain) are protected by international regulations but are also threatened by the expansion of animal farms. We studied the input–output budgets of N from animal farms in four catchments of wetlands in the central Ebro Basin designated as Nitrate Vulnerable Zones. We used the N produced in animal farms as inputs and the N extracted by the crops on which manures and slurries are applied as outputs in each catchment. The balances considered the regulations concerning the slope of land where animal excreta may be applied and the doses of application. At a detailed scale, we applied the Water Erosion Prediction Program (WEPP) to the Farnaca catchment to assess the runoff and nutrients arriving to its wetland. While the Bujaraloz-Sástago basin showed a high excess of N load, in the Gallocanta basin, N extraction by crops was significantly higher than the N produced by the animal farms. Despite this lack of surplus of N from animal excreta, the groundwaters in the Gallocanta catchment are polluted by nitrates. The emphasis on N from animal farms in plans to prevent water pollution is missing the role of mineral fertilizers as the sources of pollution in basins with small N loads from animal farms. Agricultural plots in the Farnaca catchment produce significant amounts of sediments and nutrients that eventually pollute the wetland. Modelling approaches at detailed scales are required to assess the flows of materials to individual wetlands. Full article

The content of bioavailable forms of phosphorus (P) and potassium (K) in soil is essential for the proper functioning of agroecosystems. This study aimed to determine the effects of pig slurry (PS) and NPK mineral fertilizers on soil phosphorus (P) and potassium (K) fractions, the relationship between these fractions and basic soil agrochemical properties, and crop yield. The research material was collected from a long-term experiment established in 1955 in Prague-Ruzyně, Czechia. The effect of two constant factors was analyzed: manure application (control, PS) and different doses of NPK fertilizers (N₀P₀K₀, N₁P₁K₁, N₃P₂K₂, and N₄P₂K₂). A significant effect of fertilization on basic soil properties was demonstrated, including total soil carbon and nitrogen. PS and NPK fertilization also significantly affected the content of water-soluble and moderate labile fractions of P and K. These fractions were positively correlated with plant-available P and K (Mehlich 3). The best fertilization option, which resulted in the greatest increase in yield, was the use of PS and mineral fertilizers at the N₃P₂K₂ level. Increasing the nitrogen dose to the level of N₄ resulted in a decrease in the content of bioavailable forms of P and K in topsoil despite the application of PS. Full article

Portuguese farmers seek evidence that organic fertilisers, particularly manure-based ones, can be safely used as partial replacements for mineral fertilisers (MFs), taking advantage of their nutrient and organic matter (OM) content. This study aimed to clarify the effects of applying organic fertilisers, especially under no-till practices in maize production. The experiment involved replacing basal mineral nitrogen (N) fertilisation with composted animal manure (CM) and pig slurry (PS) across three contrasting fields with varying soil characteristics, tillage techniques, and OM supplementation. Results indicated that site 1, which had the lowest clay and OM content, benefited the most from organic fertilisers, particularly in enhanced nutrient absorption in both maize leaves and grain. In this site, partial nutrient balance of N was significantly higher in the PS treatment (0.56 kg grain N exported kg N applied⁻¹) compared with the treatment with only MF (0.44). The impacts on greenhouse gas (GHG) emissions depended on site characteristics. CM led to higher emissions at site 2 (CH₄) and site 3 (N₂O), while PS did not increase GHG emissions at any site. Under no-till practices at site 3, CM resulted in higher global warming potential (154 kg CO_2-eq ha⁻¹) compared with the PS (128 kg CO_2-eq ha⁻¹) and MF (109 kg CO_2-eq ha⁻¹) treatments. Overall, this study suggests that organic fertilisers, particularly PS, can be a viable strategy for improving soil health and maintaining sustainable maize production in Portuguese agriculture. However, their effectiveness depends on factors such as soil texture, OM content, and tillage practices. In soils with lower OM content or under no-till practices, pig slurry emerges as a suitable alternative, replacing 30% of total mineral N fertilisation without compromising productivity or increasing GHG emissions. Full article

Cyperus esculentus is an invasive sedge causing high losses in many crops. Prevention is key in minimizing further spread and damage. Propagules (tubers or seeds) may spread via cattle manure. This study examined the effect of ensiling, digestion, and storage in manure on the viability of C. esculentus propagules. Propagules were subjected to five durations (0–16 weeks) in silage maize, seven durations (0–48 h) of ruminal digestion, and five durations of storage (0–16 weeks) in manure (slurry or farmyard), or combinations of previous processes. Afterwards, the viabilities were determined by a germination and tetrazolium test. After 6 weeks in a maize silo, the viability of the propagules was reduced by at least 96%. Incubation for 36 h in the rumen, followed by post-ruminal digestion in vitro, reduced seed viability by 30%. However, for the tubers, no effect was observed. The viability of seeds and tubers was reduced by 90% after 11.5 and 13.7 weeks of incubation in slurry, respectively. Compared with seeds, tubers were less tolerant to 12–24 h of animal digestion, followed by 8 weeks of storage in slurry. Keeping a maize silo closed for at least 6 weeks and maintaining slurry storage for at least 16 weeks are excellent measures to eliminate C. esculentus. For farmers, these preventive measures are relatively easy and cheap to implement compared to the requirements of curative control methods. Full article

The global production of brewers’ spent grains (BSG) is 37 million tons yearly. Composting represents an eco-friendly method to manage and valorize organic by-products in a circular economy model. This project aims to compare two BSG bin-composting mixtures (BSG and wheat straw with pig slurry solid fraction, MIX1, or sheep manure, MIX2) and approaches (manual turning, MT, and static composting, ST). The two mixtures’ physicochemical characteristics and greenhouse gas (GHG) emissions were assessed during the process. The evolution of physicochemical properties is reported in detail. Headspace samples of GHG emissions were collected and analyzed with gas chromatography coupled with specific detectors. Carbon dioxide (CO₂) emissions were 34.3 ± 0.03 and 31.0 ± 0.06 g C kg⁻¹ fresh matter (FM) for MIX1-MT and MIX2-MT, and 28.8 ± 0.01 and 31.2 ± 0.02 g Ckg⁻¹ FM for MIX1-ST and MIX2-ST. Methane emissions were negligible (all conditions < 0.086 ± 0.00 mg C kg⁻¹ FM). Nitrous oxide (N₂O) emissions from composting are affected by the substrate, bulking material, pile dimension, and manure. Particularly, the total emissions of N₂O, estimated as CO₂ equivalents, were 45.8 ± 0.2 and 63.0 ± 0.4 g CO₂ eq kg⁻¹ FM for MIX1-MT and MIX1-ST, respectively. In both composting approaches, MIX2 showed a low CO₂ equivalent (1.8 ± 0.02 and 9.9 ± 0.05 g CO₂ eq kg⁻¹ FM for MT and ST), likely due to incomplete decomposition. The bin-composting process represents a solution for recycling and reusing organic waste and livestock manure in small to medium-sized breweries. The solid fraction of the pig slurry resulted in the most suitable manure. Full article

Maize double-cropping production systems in Mediterranean areas have a great nitrogen extraction capacity and high nitrogen (N) requirements. This study aims to assess whether in these farming systems, animal manure can be applied, using adequate management practices, at levels exceeding the maximum annual amount of livestock manure established in the European Nitrate Directive for vulnerable zones (170 kg N ha⁻¹) without increasing the risk of water nitrate contamination. We compare the risk of nitrate leaching under two fertilisation strategies, one with synthetic fertilisers and the second with a maximised application of pig slurry, exceeding the limits of the EU Nitrate Directive, in two soil types. Crop yields, N extraction and nitrate concentrations below the crop root zone were not affected by the fertilisation strategies at each site. The results show that pig slurry can be applied above the limit of 170 kg N ha⁻¹ under the conditions of the study, up to 360 kg N ha⁻¹, without increasing the risk for nitrate leaching. Full article

Cover crops have many simultaneous roles that enhance the sustainability of agriculture compared to leaving land fallow in arable systems. In high rainfall climates, an important role of cover crops is to sequester nutrients, protecting them from loss to the environment. In many livestock intensive regions, organic manures are applied in autumn with land left fallow over winter and then a cash crop is planted in the spring. This practice of extended fallow, combined with the poorly synchronised application of nutrients to cash crop nutrient demand, further adds to the potential for large losses of nutrients specifically nitrogen (N) to the environment through leaching and volatilization. Therefore, if cover crops could respond to these nutrients through increased biomass growth and nutrient uptake, they could reduce these losses. Therefore, it is important to choose the correct species which grows adequately to deliver these potential benefits. In the region this study is conducted, Northern Ireland, there has been little research to investigate not only what optimum cover crop species are but also what species could respond to additional nutrients in the slurry. This study comprises two experiments, in consecutive years, including a combination of three factors: cover crop species (five species; a mixture and a control representing fallow); pig slurry. Consequently, it was found that with good growing conditions, in the trial year of 2018/19, species such as forage rape and tillage radish could significantly (p < 0.05) increase the amount of N contained in their biomass and the soil (to 15 cm) by 70 and 63%, respectively, in response to slurry. Alternatively, when slurry was applied to fallow land (conventional practice), low amounts (14 and 0% in the two trial years, respectively) of the N from the slurry were detected in weed biomass or retained in the soil. This demonstrates a large loss of N from the system. Thus, the integration of responsive cover crops with slurry is a better practice to abate N loss than conventional practice, if slurry applications can not be delayed. Full article

In a previous experiment, we showed that the odor of Bos taurus manure slurries could be improved by anaerobic incubation with the sugars glucose, lactose, and sucrose. This improvement was due to reductions in the concentrations of malodorants, including dimethyl disulfide, p-cresol, p-ethylphenol, indole, and skatole, and a shift to the production of fruity esters, including ethyl butyrate and propyl propanoate. Due to large concentrations of lactic acid produced by the sugar-amended manure slurries, we inferred that lactic acid bacteria were involved in improving the manure slurry odor. Here, through 16S rRNA amplicon sequencing for microbiome analysis, we show that lactic acid bacterial growth was promoted by the addition of all three sugars. Lactobacillus buchneri and an unknown Lactobacillus sp. were the most prominent lactic acid bacteria stimulated by sugar addition. Lactobacillales were found only in trace abundances in unamended manure slurries. The relative abundance of orders such as Clostridiales, Bifidobacteriales, and Erysipelotrichales were not noticeably affected by sugar amendment. However, the disaccharides lactose and sucrose seemed to increase the relative abundance of Bifidobacterium, whereas the monosaccharide glucose did not. We conclude that lactic acid bacteria are the primary bacteria involved in improving odor in dairy cow manure slurries and present strategies to enhance their abundance in animal wastes. Full article

With the rapid development of the animal farming industry in China, the large amount of manure has caused a systematic environmental problem, while the demand for high-quality feed continues to increase. The application of dairy cattle slurry to alfalfa fields is a simple and inexpensive solution to the problems above. A repacked soil column study was conducted to investigate the effect of slurry nitrogen (N) on alfalfa biomass, as well as its photosynthetic characteristics. Dairy cattle slurry N or mineral fertilizer N was applied in two dressings at the first cut, with a target amount of 90 kg ha⁻¹. A non-fertilization control (CK), a single mineral fertilizer N (MIN), and a slurry substitution for mineral N fertilizers (with equivalent N rate: FPS, 50% N from dairy cattle slurry; SLU, 100% N from dairy cattle slurry) were used. The results show that the slurry N increased the alfalfa biomass by 16.40–36.36% and the SPAD value by 30.27–61.34% with FPS and SLU treatments, respectively. Compared to the CK treatment, the FPS and SLU treatments meaningfully increased the net photosynthetic rate by 19.97–60.04% and 3.03–89.48%, the stomatal conductance by 10.53–57.14% and 15.38–88.89%, the intercellular CO₂ concentration by 5.78–24.92% and 7.21–32.53%, and the transpiration rate by 13.16–103.50% and 16.44–111.19%. More specifically, compared with the CK treatment, the N absorption of the SLU treatment increased by 6.78–12.30%, and the use efficiency increased by 30.98–46.60% in the SLU treatment. Similarly, phosphorus (P) absorption of the SLU treatment increased by 36.73–52.57%, and the use efficiency increased by 30.98–46.60%. Overall, the dairy cattle slurry N was utilized efficiently as mineral N for alfalfa biomass, improved the photosynthetic characteristics of alfalfa leaves, and increased the N and P use efficiency. Our results clarify the optimal amount of dairy cattle slurry to be applied and provide a scientific basis for the use of dairy cattle slurry in agricultural systems. Full article

Microbial fuel cells (MFCs) and microalgae–bacteria consortia represent two renewable and promising technologies of growing interest that enable wastewater treatment while obtaining high-value-added products. This study integrates MFCs and microalgae production systems to treat animal slurry, aiming to remove and recover organic and inorganic components while generating energy and producing biomass. The MFCs effectively eliminated Chemical Oxygen Demand (COD), organic nitrogen, and a portion of the suspended solids, achieving a maximum voltage of 195 mV and a power density of 87.03 mW·m⁻². After pre-treatment with MFCs, the slurry was diluted to concentrations of 10%, 50%, and 100% and treated with microalgae–bacteria consortia. The results showed a biomass production of 0.51 g·L⁻¹ and a productivity of 0.04 g·L⁻¹·day⁻¹ in the culture fed with 10% slurry, with significant removal efficiencies: 40.71% for COD, 97.76% for N-NH₄₊, 39.66% for N-NO₂⁻, 47.37% for N-NO₃⁻, and 94.37% for P-PO₄⁻³. The combination of both technologies allowed for obtaining a properly purified slurry and the recovery of nutrients in the form of bioelectricity and high-value biomass. Increasing the concentration of animal slurry to be treated is essential to optimize and scale both technologies. Full article

Soil in karst areas is rare and precious, and karst carbon sinks play an important role in the global carbon cycle. Therefore, the purpose of karst soil improvement is to improve soil productivity and a carbon sink effect. Biomass amendment experiments in this study included three schemes: filter mud (FM), filter mud + straw + biogas slurry (FSB), and filter mud + straw + cow manure (FSC). The characteristics of soil CO₂ production, transport, and the effect on soil respiration carbon emissions in two years were compared and analyzed. The results were as follows: 1. The rate, amount, and depth of CO₂ concentration were affected by the combinations with biogas slurry (easy to leach) or cow manure (difficult to decompose). 2. The diurnal variation curves of soil respiration in the FSB- and FSC-improved soils lagged behind those in the control soil for three hours. While the curves of FM-improved soil and the control soil were nearly the same. 3. Soil–air carbon emissions increased by 35.2 tCO₂/(km²·a⁻¹) under the FM scheme, decreased by 212.9 tCO₂/(km²·a⁻¹) under the FSB scheme, and increased by 279.5 tCO₂/(km²·a⁻¹) under the FSC scheme. The results were related to weather CO₂ accumulation in the deep or surface layers under different schemes. Full article

Determining nutrient-release patterns of organic manures can give an estimate of the potential amount of nutrients that a given material can contribute to crops along with chemical fertiliser. Nutrients released from organic manure depend on several factors, and temperature is one of them. To evaluate how different types of conventional organic manures release nitrogen (N) under varying temperature conditions, an incubation study was conducted at the Bangladesh Agricultural Research Institute. Six organic manures—poultry manure (PM), vermicompost (VC), bio-slurry (BS), cowdung (CD), water-hyacinth compost (WHC), and rice straw compost (RSC)—were evaluated at three temperature regimes (15, 25, and 35 °C) to study the dynamics of N incubated for 330 days. The N release was significantly influenced by the interaction of organic manures and temperature regimes. Poultry manure-treated soil incubated at 35 °C had the highest mineralisation of all parameters than other manures. The mineralisation of N followed the order: PM > VC > BS > CD > WHC > RSC > control and 35 °C > 25 °C > 15 °C. Across different temperatures, the mineralisation rate of PM was 15–55% higher than that of other manures. At 35 °C, the mineralisation rate was 10% and 20% higher compared to 25 °C and 15 °C, respectively. The first-order kinetic models predicted the organic N release from manures satisfactorily. The findings of the present study enrich the understanding of N-release patterns under different temperature regimes that prevail in different crop growing seasons in Indo-Gangetic Plains, providing valuable data for researchers and policymakers interested in sustainable integrated nutrient management practices. Full article

The sustainable management of pig slurry (PS) in intensive farms is essential to reduce adverse environmental impacts and reduce the ecological footprint. If not managed properly, PS can release GHG/NH₃ gases into the atmosphere and contaminate waters. This study evaluates the impact of an integral management system with physical and biological stages to mitigate the impact of PS. The system resulted in effective PS traceability, studying its physicochemical properties. The synergism in the whole system allowed a decrease in the most analyzed parameters during the autumn, spring, and summer. The pretreatment contributed significantly to obtaining an appreciable percentage of reduction in the constructed wetlands of SS (99–100%), COD (56–87%), TN (50–57%), and PO₄³⁻ (88–100%). The emission values (g/m²/day) were 0–2.14 (CH₄), 0–473.76 (CO₂), 0–179.77 (H₂O), 0–0.265 (N₂O), and 0–0.195 (NH₃), highlighting the raw, separated and manure fractions with the highest values. It is concluded that the system proves to be a practical, low-cost, and efficient technique for the treatment of PS. It significantly reduces the concentration of nutrients, and the intercepted byproducts can be valuable for application to the soil. In addition, the system effectively reduces GHG/NH₃ emissions in decanted, purified, and wetland PS fractions. Full article

Ammonium inhibition is a key limiting factor for anaerobic digestion when using chicken manure as the main substrate, especially in a digestion system with biogas slurry reflux. Air stripping is usually used as a recycled biogas slurry treatment. In this study, we carried out the anaerobic co-digestion of chicken manure and corn straw. The fermentation performance was investigated with and without air stripping at different biogas slurry reflux ratios and with an increasing organic loading rate. The results show that air stripping enhanced biogas production, system stability, and volatile solid removal efficiency via the mitigation control of ammonium inhibition. The total ammonium nitrogen in the digesters with air stripping was 20.24–46.40% lower than in those without air stripping. The highest specific biogas production and volatile solid removal efficiency values were obtained in the digesters at an organic loading rate of 3.3 g volatile solid (VS)/(L·d) and a reflux ratio of 75% with air stripping, reaching 480.43 mL/gVS_add and 63.36%, respectively. Moreover, air stripping also improved the organic loading rate and reflux ratio. Stable operation was achieved at an organic loading rate of 5.3 gVS/(L·d) and a reflux ratio of 75%, with specific biogas production of 392.35 mL/gVS_add and a volatile solid removal efficiency of 50.33%. The fermentation performance deteriorated when the organic loading rate was increased to 8.0 gVS/(L·d) at a reflux ratio of 75%, even when air stripping was conducted, indicating that a slighter lower reflux ratio (50%) could be more feasible at a higher organic loading rate (8.0 gVS/(L·d). Additionally, the methanogen community structure varied according to the use of air stripping, with a shift in the methanogenic pathway from hydrogenotrophic to acetoclastic methanogens. Overall, our findings support the adoption of air stripping for ammonium mitigation in anaerobic digestion with biogas slurry reflux. Full article