Manure Characteristics Research Articles

An Investigation on a Comprehensive Calibration Technique to Determine the Discrete Elemental Characteristics of Unrotted Sheep Dung at Varying Water Concentrations

An experimental study was undertaken to investigate the problem of the substantial variability in water content in unrotted sheep dung, which leads to a lack of universality and practicality in calibrating its discrete element simulation parameters. The stacking angle was used as the response value in these experiments. The objective of this study was to establish precise simulation parameters for the composting process. A model for water content-stacking angle was established using the cylinder-lifting technique, resulting in a correlation value of 0.997. Utilizing the Hertz–Mindlin with JKR bonding model, three EDEM particle models were developed, each with distinct particle sizes, based on the particle size distribution of sheep dung. The JKR surface energy was determined using the Plackett–Burman test, the steepest-climbing test, and the Box–Behnken test using a set of 10 parameters. A subsequent study was conducted on the JKR surface energy, rolling friction factor, and static friction factor utilizing the Plackett–Burman test and Box–Behnken test. A parameter model for stacking angle–discrete elements was developed that achieved a p-value below 0.0001 and a relative inaccuracy of 3.46% or less. The regression model for the water content–discrete element parameter was derived by combining the water content–stacking angle model with the stacking angle–discrete element parameter model. Validation of this model was conducted using both the pumping plate technique and the hopper approach, resulting in a relative error of 4.89% or less. The findings demonstrate that the specific characteristics of sheep manure may be accurately anticipated by considering its water content. This approach offers a valid and universally applicable way of predicting the specific characteristics of sheep dung in the simulation of composting equipment.

Impact of lowering nitrogen content in pig manure through low crude protein diets on anaerobic digestion process stability, biogas yields, and digestate composition

Lowering crude protein in pig diets can reduce nitrogen (N) excretion and alter manure characteristics. Anaerobic digestion (AD) offers potential for converting pig manure into biogas and bio-based fertilizers (i.e., digestate). However, limited research exists on the effects of N content in pig manure on AD when pigs are fed diets with varying crude protein levels. This study investigated how lowering N content in pig manure through low crude protein diets may affect AD process stability, biogas generation, and digestate properties. Manures from different dietary treatments, named as control (CON), low N (LN), and very low N (VLN), with Total Kjeldahl Nitrogen concentrations of 5.87, 5.42, and 5.15 g/L, respectively, were investigated. Daily biogas production, composition (CH4, CO2, and H2S), and digestate properties were monitored over 13 fed-batch cycles (25 ± 4 days per cycle). The experiment was conducted at 20 ± 1 °C, a condition suited for milder climate regions, using six single-stage digesters operated in sequencing fed-batch mode. Data were analyzed by ANOVA using PROC MIXED with repeated measures. Results showed that the differences in N content in pig manure due to the three dietary treatments had a limited impact on biogas generation, with specific methane yields remaining similar over time. CH4 concentrations remained stable between 60 and 65 %, ensuring high-quality biogas despite dietary variations. Differences between treatments became more pronounced with increased organic loading rates (OLRs) due to variations in the amount of volatile solids fed. AD also remained stable (Total Volatile Fatty Acids/Total Alkalinity <0.25) even at an OLR of 2.15 g of chemical oxygen demand L−1 day−1, highlighting AD's robustness at lower temperatures. Digestate samples contained essential minerals beneficial for plant growth. More research is needed to explore varied manure compositions and feeding strategies to better understand the interactions of animal nutrition with AD.

Pelatihan Petani dalam Produksi Pupuk Organik di Desa Tegalgede, Kecamatan Sumbersari, Kabupaten Jember

Chemical fertilizers are increasingly rare and expensive, causing farmers (partners) to look for solutiosn by using organic fertilizer as a combination. However, a problem is currently being faced by partners, namely related to the production process of organic fertilizer made from goat manure. The characteristics of goat manure are hard, and it takes quite a long time to decompose, so farmers have to wait approximately one month before it can be applied as basic fertilizer on agricultural land. Efforts to speed up the decomposition process have been made by partners, namely by crushing or smoothing goat manure by pounding it manually. This stage requires quite a lot of time and energy, so it is felt to be less efficient. This is due to the lack of technology adopted in the partner environment. Based on the conditions and problems faced by partners, through this activity a solution will be offered in the form of technology for processing goat manure as raw material for organic fertilizer. This technology is in the form of a goat manure crushing machine to help speed up the decomposition process and provide nutrients, so that partners do not have to wait long for planting to start. This community service activity is carried out by providing counseling and training in making organic fertilizer from goat dung as raw material, accompanied by the use of a goat dung crushing machine. It is hoped that partners’ knowledge and skills can increase, especially in processing organic fertilizer made from goat manure.

The Effect of Absorbent Level and Inoculants on Chemical Composition and Fermentation Characteristics of Fermented Poultry Manure as an Unconventional Feed Ingredient

Abstract The aim of the present study was to investigate the effect of absorbent level and microbial inoculant on chemical compositions and fermentation characteristics of fermented poultry manure (FPM). In the first trial, the FPM was fermented using two levels of cassava solid waste as absorbent, consisted of 10% (AL10) and 30% (AL30). The best absorbent level to improve the quality of FPM was continued in the second trial. In the second trial, FPM was fermented using inoculant treatments following without inoculants (CON), Lactobacillus plantarum (LP) and multi-purpose microbes (MP). All fermentation was conducted for 14 d in 4 kg mini-silo with quadruplicate. In the first trial, AL30 had higher levels of dry matter and crude fiber but lower levels of crude protein, ether extract, and butyric acid content compared to AL10 (P&lt;0.05). In the second trial, CON presented higher levels of dry matter, crude protein, and crude fiber, but lower levels of ether extract, nitrogen-free extract, pH, ammonia, and butyric acid compared to LP and MP (P&lt;0.05). In conclusion, the present study found that FPM without inoculant at the 30% absorbent level resulted in higher nutrient composition and better fermentation characteristics compared to other treatments.

Aerobic composting characteristics of corn straw and pig manure under dynamic aeration

ABSTRACT The conventional aeration method is compulsorily continuous ventilation or aeration at equal intervals, and a uniform aeration rate does not vary during composting. A dynamic on-demand aeration approach based on the diverse oxygen consumption of microorganisms at different composting stages could solve the problems of insufficient oxygen supply or excessive aeration. This study aims to design an aerobic composting system with dynamic aeration, investigate the effects of dynamic aeration on the temperature rise and physicochemical characteristics during the aerobic composting of corn straw and pig manure, and optimise the control parameters of oxygen concentration. Higher temperatures and longer high-temperature durations were achieved under dynamic aeration, thereby accelerating the decomposition of organic compounds. Dynamic aeration effectively reduced the aeration frequency, the convective latent heat and moisture losses, and the power consumption in the middle and later stages of composting. The dynamic aeration regulated according to the oxygen concentration of 14%–17% in the exhaust was optimum. Under the optimal conditions, the period above 50 ℃ lasted 8.5 days, and the highest temperature, organic matter removal, and seed germination index reached 65.82 ℃, 37.59%, and 74.59%, respectively. The power consumption was decreased by 33.58% compared to the traditional intermittent aeration. Dynamic aeration would be a competitive approach for improving aerobic composting characteristics and reducing the power consumption and the hot exhaust gas emissions, especially in the cooling maturation stage, which was of great significance for realising the low-cost production of composting at scale and promoting the blossom of the organic fertiliser industry.

Effects of swine manure and straw biochars on fluorine adsorption-desorption in soils.

With increasing global awareness of soil health, attention must be paid to fluorine exposure in soils, which poses a threat to human health. Therefore, this study aimed to study the fluorine adsorption characteristics of swine manure and straw biochars and their impact on fluorine adsorption-desorption in soil with batch experiments. The biochar samples originated from high-temperature anaerobic cracking of swine manure (350°C, 500°C, and 650°C) and straw (500°C). Results indicated that the adsorption of soil fluorine reached adsorption equilibrium at around 4 h after the mixing of swine manure and straw biochar. Fluorine adsorption kinetics using these biochars conformed to the quasi-two-stage kinetic model. The fluorine adsorption kinetics for biochar-treated soils conformed to the double-constant equation and the Elovich equation, and the soil treated with straw biochar showed the fastest fluorine adsorption rate. The adsorption isotherms of fluorine for biochars and biochar-treated soils could be fitted by the isothermal adsorption model of Langmuir and Freundlich. The maximal equilibrium quantity of fluorine was 73.66 mg/g for swine manure biochar. The soil, adding with 2% of swine manure biochar achieved with showed at 650°C had the smallest adsorption. This study also shows that the adsorption of fluorine by biochar gradually decreased with the increase of pH. Comparing with other factors, the mixture pH with biochars added had a significant effect on fluorine adsorption. The decreased fluorine adsorption capacities for soils treated with swine manure and straw biochars were closely related to the increased pH in soils after adding biochars. Considering the fluorine threat in soil, this study provides a theoretical basis for the application of biochars on soil fluorine adsorption.

Effects of Brassinosteroid Hormone on Chemical Composition of Okra (Abelmoschus esculentus L.) under Salt Stress

Following the scientific management of organic manure (poultry) may contribute to reducing environmental pollution and human health, as the current study was conducted with the aim of recycling poultry manure accumulated in the field of poultry farming at the research station - Faculty of Agriculture - Karma site and the impact of varying fermentation durations on organic manure, specifically animal (poultry manure) fermented by different fermentation methods and its impact on the rest of the factors to produce highly decomposed organic manure free of pathogens. Several traditional fermentation methods (compost and water immersion) were followed. and modern (bioreactor), and for a fermentation period of 90 days with an estimate of most of the qualitative characteristics of the organic manure produced and within periods of 15 - 30 - 45 - 60 - 75 - 90 days. The results of the experiment of incubation of poultry manure showed that all the studied traits have changed with the progress of fermentation time and in the same direction, the results demonstrated that fermentation in the bioreactor unit has given the highest values of total nitrogen, total phosphorus and potassium 32.53, 16.72, 20.86, g.kg-1 for the elements mentioned sequentially, while the lowest values of pH 6.68 and C/N ratio 9.96 compared to other fermentation methods.

Effect of fermentation periods of poultry manure on its characteristics when fermented with different ways

Following the scientific management of organic manure (poultry) may contribute to reducing environmental pollution and human health, as the current study was conducted with the aim of recycling poultry manure accumulated in the field of poultry farming at the research station - Faculty of Agriculture - Karma site and the impact of varying fermentation durations on organic manure, specifically animal (poultry manure) fermented by different fermentation methods and its impact on the rest of the factors to produce highly decomposed organic manure free of pathogens. Several traditional fermentation methods (compost and water immersion) were followed. and modern (bioreactor), and for a fermentation period of 90 days with an estimate of most of the qualitative characteristics of the organic manure produced and within periods of 15 - 30 - 45 - 60 - 75 - 90 days. The results of the experiment of incubation of poultry manure showed that all the studied traits have changed with the progress of fermentation time and in the same direction, the results demonstrated that fermentation in the bioreactor unit has given the highest values of total nitrogen, total phosphorus and potassium 32.53, 16.72, 20.86, g.kg-1 for the elements mentioned sequentially, while the lowest values of pH 6.68 and C/N ratio 9.96 compared to other fermentation methods.

Evaluation of the decomposition ability and characteristics of pig manure treated with different larval instar stages of black soldier fly (Hermetia illucens L.)

AbstractWaste treatment using black soldier fly (BSF; Hermetia illucens L.) larvae is an emerging technology that reduces livestock manure disposal. This study aimed to evaluate the effect of different growth stage BSF larvae on the decomposition potential (Experiment 1) and characteristics (Experiment 2) of pig manure. BSF larval instars were randomly divided in three groups according to their developmental stage, with three replicates per group, using a randomized block design. Each treatment group consisted of 1 kg of 2nd, 3rd, or 4th instar BSF larvae added in 10 kg of pig manure (Group 1, 2, or 3, respectively). In Experiment 1, 2nd and 3rd instar BSF larvae treatments resulted in greater decomposition levels of pig manure compared with 4th instar BSF larvae groups. In Experiment 2, BSF larvae improved the nutrient content of manure, leading to an increase in the total nitrogen levels and a decrease in total carbon content and C:N ratio, rendering it suitable for use as an organic fertilizer. In addition, the increased N levels of treated BSF manure were not related to lower pH levels. BSF larvae can greatly reduce ADF and NDF pig manure contents as a result of the larvae's waste reduction potential. Overall, BSF 3rd instar larvae have proven to be a useful tool for the sustainable management of pig manure by strongly increasing its decomposition ability and can be an organic fertilizer for agricultural purposes that reduce ADF and NDF contents through composting.

Effect of Dietary Supplemention with Sargassum muticum algae and Pulicaria Undulate (Rabol) on Growth Performance, Blood Parameters, Immune Response, Manure Characteristics and Ammonia Emissions of Broilers.

Effect of Dietary Supplemention with Sargassum muticum algae and Pulicaria Undulate (Rabol) on Growth Performance, Blood Parameters, Immune Response, Manure Characteristics and Ammonia Emissions of Broilers.

A Review on the Anaerobic Co-Digestion of Livestock Manures in the Context of Sustainable Waste Management

As the worldwide demand for meat per person is continuously increasing, there is a corresponding rise in the number of livestock animals, leading to an increase in livestock manure. Selecting appropriate treatment technologies for livestock manures is still a complex task and considerable debates over this issue persist. To develop a more comprehensive understanding of the manure treatment framework, this review was undertaken to assess the most utilized manure management technologies and underscore their respective challenges. Anaerobic digestion has become a commercial reality for treating livestock manures. However, the mono-digestion of single substrates comes with certain drawbacks associated with manure characteristics. Anaerobic co-digestion, involving the utilization of multiple feedstocks, holds the potential to overcome these limitations. Extensive research and development have underscored numerous intrinsic benefits of co-digestion. These include improved digestibility resulting from the synergistic effects of co-substrates and enhanced process stability. This review underscores the limitations associated with the mono-digestion of livestock manures and critically evaluates the advantages of their co-digestion with carbon-rich substrates. Additionally, this review delves into key livestock manure management practices globally, emphasizing the significance of co-digesting livestock manures while addressing the progress and challenges in this field.

Energy recovery from poultry manure: a viable solution to reduce poultry industry energy consumption

As the global energy demand shows a steady growth, the energy framework becomes more restrictive in reference to the environmental impact and judicious use of resources. In this context, energy recovery from renewable waste stands out as a promising technology to deal with large amounts of different wastes while producing energy. This paper addresses the poultry manure waste treatment from the energy recovery perspective. After a brief overview of available technologies for energy valorization of animal manure, the physical-chemical characteristics of poultry manure are investigated through experimental determinations. Further, a case study is presented in reference to the energy recovery potential of a birdhouse with a livestock of 2 000 birds per cycle, located in Southern Romania. The assessment carried out within this research proves that, by locally using the poultry manure as a feedstock for energy generation, the savings in terms of electricity consumption get to 100%. Moreover, it is no longer necessary to store large quantities of waste.

Toward smallholder bamboo-integrated agro-silvopastoral systems in sub-Saharan Africa: assessing the impact of bamboo leaves on consumption pattern, growth performance and manure characteristics of West African dwarf goats

IntroductionThe selection of appropriate plant species, particularly those tailored to supplement ruminants raised under agrosilvopastoral systems, remains a persistent challenge.ObjectiveIn a 30-day study, the feed intake, growth performance, and manure characteristics of West African dwarf (WAD) goats fed bamboo leaf supplement were evaluated. Materials and methodsA total of 30 animals with an average weight of 9.9 ± 0.21 kg were divided into a control group, and four bamboo-supplemented groups, following a 2 x 2 factorial arrangement within a completely randomized design. Each group had six animal replicates and received the following dietary treatments: T1 (control) – 400g of basal diet composed of 60% Megathyrsus maximus and 40% Bridelia ferruginea leaves per day; T2—basal diet composed of the T1 diet supplemented with 400 g of Oxytenanthera abyssinica (A. Rich.) Munro leaves per day; T3—basal diet composed of the T1 diet supplemented with 400 g of Bambusa balcooa (Beema) leaves per day; T4—basal diet composed of the T1 diet supplemented with 600 g of O. abyssinica (A. Rich.) leaves per day; and T5—basal diet composed of the T1 diet supplemented with 600 g of B. balcooa leaves per day. The data were analyzed using generalized linear model procedures in Minitab Statistical Software at a 5% significance level. ResultsThe results showed varied (p &amp;lt; 0.05) dry matter compositions spanning from 894.3 to 910 g/kg with the highest contents of crude protein (194 g/kg), nitrogen (31 g/kg), crude fibre (302 g/kg), ash (156 g/kg), acid detergent fibre (429 g/kg), and acid detergent lignin (3.6 g/kg) recorded for B. ferruginea. The leaves of Bambusa balcooa contained the highest neutral detergent fibre (481 g/kg) while M. maximus had the highest organic matter content (911 g/kg). Significant interaction effect (p &amp;lt; 0.05) was observed between the supplement type and the supplementation level, impacting various parameters including feed intake ranging from 398 g (T1) to 469 g (T3) per day, weight gain from 27 g (T1) to 72 g (T2) per day, feed conversion efficiency from 6% (T1) to 15% (T2), manure output from 241 g (T2) to 260 g (T5) per day, carbon- nitrogen (C: N) ratio from 9 (T2) to 20 (T5), faecal acidity levels from 4 (T1) to 5 (T4). Comparatively, higher daily dry matter intake was recorded for the animal groups fed the B. balcooa supplement than their counterparts fed the O. abyssinica supplement. However, the O. abyssinica supplemented groups were more efficient in converting feed to body weight, with feed conversion efficiency approximately 9% higher than the B. balcooa-supplemented groups. Furthermore, in general, the animal groups that received a daily supplement of 400 g gave higher feed efficiency, with performance approximately 3.2% higher compared to the groups receiving 600 g. Likewise, these groups displayed higher faecal N output while concurrently achieving a reduced C: N ratio, indicative of enhanced nutrient utilization and potential environmental benefits. ConclusionTo conclude, integrating 400 grams of bamboo leaves into animal diet can enhance basal diet consumption, accelerate animal growth, and yield manure akin to chemical fertilizers, making it a valuable strategy for bamboo-integrated agro-silvopastoral systems practitioners.

Study on Anaerobic Digestion Characteristics of Hulless Barley Straw and Livestock Manure

Study on Anaerobic Digestion Characteristics of Hulless Barley Straw and Livestock Manure

Study on Low Temperature Drying Characteristics of Chicken Manure in a Humid Environment

Drying chicken manure with exhaust air from a chicken house is a new manure management method developed in recent years. The majority of the heat for this drying method comes from the waste heat of ventilation in a poultry house or ambient air, so the drying process is carried out at a low temperature. When met with continuous rain or when the wet curtain in the chicken house is turned on, the relative humidity of the exhaust air from the chicken house will rise to high levels, and the drying process will be under the condition of high relative humidity. In order to explore the low-temperature drying characteristics of chicken manure in a humid environment, drying experiments were carried out in an experimental cross-flow drying system. The experiment mainly studied the effect of process parameters such as drying temperature, air velocity, and manure layer thickness on the low-temperature drying characteristics of chicken manure in a humid environment. The results showed that the low-temperature drying process of chicken manure in a humid environment only had a falling rate period, with no accelerated or constant rate period. Additionally, five common thin-layer drying models (Lewis model, Page model, Henderson and Pabis model, Wang and Singh model, and Exponential model) were applied to simulate the performance of the manure drying process. The exponential model was considered to be more suitable for describing the low temperature drying process in a humid environment, and the effective diffusivity changed between 6.37 × 10−7 and 2.17 × 10−6 m2/h.

Analysis of Manure Separation Technology Efficiency into Fractions Followed by Liquid Fraction Rectification

Introduction. There is not enough data on the used intensive technologies of processing pig manure into organic fertilizer to accurately calculate the content of nutrients in the final products and, accordingly, their doses of application. Aim of the Article. To determine the efficiency of pig manure processing technology, which includes liquid fraction rectification, by the quantitative and qualitative characteristics of manure and final products, and to trace the redistributing total nitrogen between the final products on the example of a pilot pig breeding complex production. Materials and Methods. For the study, there was chosen a typical pig-breeding complex, where the pig manure processing included slurry acidification, flocculation, separation into fractions in a decanter centrifuge, rectification of liquid fraction, passive composting of solid fraction, and long-term storing of liquid fraction. The technology allows producing three types of end products: solid organic fertilizer, concentrated liquid (ammonia water), and fertilizer solution. Quantity and quality of pig manure and the end products were calculated by the known methods. Experimental studies were performed to compare the results. Samples were analyzed in the analytical laboratory of Institute for Engineering and Environmental Problems in Agricultural Production in 2022. Three replications were carried out for each sample. The experimental data were statistically analysed in MS Excel. Results. Quantitative and qualitative characteristics of pig manure, its solid and liquid fractions, and end products were calculated. The difference between the calculated and actual values does not exceed 10.2% that indicates the reliability of calculations. Discussion and Conclusion. The introduction of a new technology at the pig-breeding complex has reduced atmospheric emissions by 10% due to the nitrogen conservation, has reduced operating costs for transporting organic fertilizer by 47% due to the concentration of nutrients in a smaller volume and has improved soil fertility through fertilizer irrigation.

Assessment of the biochemical methane potential of in-house and outdoor stored pig and dairy cow manure by evaluating chemical composition and storage conditions

Biogas production is a suitable option for producing energy from dairy and pig manure types. During manure storage, organic matter degradation results in methane emissions decreasing the potential biogas yield. The present research advances the understanding of the biochemical methane potential (BMP) and the chemical characteristics of manure collected year-round from sequential stages of the liquid manure management chain of commercial dairy cow and pig farms. To this end, manure samples from six livestock farms in Germany were analyzed. The results showed that changes in chemical composition during storage led to a 20.5% decrease in the BMP of dairy manure from the barn to outdoor storage. For fattening pig manure samples, there was a 39.5% decrease in the BMP from intermediate to outdoor storage. An analysis of BMP according to manure age showed that pig manure degrades faster than dairy manure; the importance of promptly feeding manure to the biogas plant in order to avoid significant CH4 emission losses and reduction in energy producing capacity was highlighted. The best BMP predictors for dairy manure were the contents of dry matter, volatile solids and lignin, whereas best BMP predictors for pig manure were dry matter and volatile fatty acid (VFA) content. Prediction models performed well for samples from outdoor storages; refinements for predicting BMP of less aged samples presenting lower chemical variability would be necessary.

Determination of Pyrolysis and Kinetics Characteristics of Chicken Manure Using Thermogravimetric Analysis Coupled with Particle Swarm Optimization

The valorization of chicken manure via pyrolysis can give biowaste a second life to generate value and contribute to the circular economy. In the present study, the thermal degradation and pyrolysis characteristics of chicken manure pyrolysis were investigated via thermogravimetric analyses (TGA) coupled with optimization methods. Thermogravimetric data were obtained for the samples at five heating rates of 5, 10, 20, 30 and 50 °C/min over a range of temperature under inert conditions. The manure devolatilization process was initiated at between 328 and 367 °C to overcome the global activation energy barrier. The determined activation energy of the manure via Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), Friedman and Kissinger methods was in the range of 167.5–213.9 kJ/mol. By using the particle swarm optimization (PSO) method, the pyrolytic kinetic parameters of the individual component present in the manure were calculated, in which the activation energy for cellulose (227.8 kJ/mol) was found to be higher than that of hemicellulose (119 kJ/mol) and lignin (134.3 kJ/mol). Based on intrinsic transition-state theory, the pre-exponential factor and activation energy of the manure can be correlated through a linear equation ln Aα = 0.2006 Eα − 1.2847. The devolatilization characteristics of the chicken manure were elucidated via the optimization process, paving the way for the design of thermochemical conversion reactors and processes.

Estimation of short- and long-term floor and ceiling prices for manure in a crop and livestock farms exchange

Abstract Organic matter is a key element of soil fertility. However, in-soil stocks of organic matter are in decline in specialized crop farms. Reintroducing organic fertilizers could be a way to increase or at least maintain organic matter stocks in these soils. Straw/manure exchanges between crop farms and livestock farms could improve overall land fertility and thus the long-term income of farmers. Here we used a bioeconomic model to estimate the agronomic and economic benefits of straw/manure exchanges as part of a strategy to improve soil fertility. Iterative simulations were run with prices of farmyard manure varying from €0 to €20 ton−1 to identify the price at which a crop farm can buy manure and sell straw without degrading its net income (manure ceiling price) compared to purchasing mineral fertilizer only and ploughing back straw. Parallel simulations were run to identify the price at which a livestock farmer can sell manure and buy straw without degrading its net income (manure floor price) compared to keeping all manure on the farm and buying straw on the market. The key new contributions of this study are that it (i) considers the characteristics of manure beyond its short-term fertilizing value, i.e., better mineralization of humus and a 10% increase in crop yields, (ii) estimates both the economic and agronomic benefits of manure and (iii) assesses the impacts of uncertainties on manure effects and prices. The results show that it is profitable for a French farmer in a conventional field crop system to buy manure at a price between €10 ton−1 in the short term and €18 ton−1 in the long term. The results also show that it is still economically advantageous for a livestock farmer to sell part of their manure, even at a very low price. This study shows that it is possible to better distribute manure resources over a territory in a way that enriches the soils of crop farms without degrading the soils of livestock farms.

Effect of Mechanical Solids Separators on Potential Reduction of Methane Emissions From Dairy Manure Storage

Highlights Four mechanical manure separators were evaluated in on-farm studies. Mass balances and biochemical methane potential tests were conducted to measure on-farm separation efficiencies. Separator performance depended on environmental, material, and design factors. Over 70% solids separation and methane emission reduction potentials were achieved. Abstract. The separation efficiencies of four mechanical solid-liquid separation technologies and their effect on the reduction of methane production potential from dairy lagoons were studied using on-farm separator measurements and laboratory biomethane potential tests. The studied technologies included 1-stage sloped dual-screen, 2-stage sloped dual-screen, 1-stage horizontal scraped screen, and 1-stage sloped single-screen separators. The technologies were evaluated across various seasons on four dairies in California. On-farm sampling and measurements of the influent of flushed manure and the mass of the solids separated, as well as in-laboratory measurements of methane (CH4) production potential, were carried out. A mass balance approach was employed to determine the removal efficiencies of total and volatile solids (TS and VS) and nutrients, as well as methane emission reduction potential. The performance of the separators depended on manure characteristics, system design (e.g., screen size and orientation), separator operation and management (e.g., manure flow rate), and manure processing pit type and configuration. Among the four studied separator systems, the 2-stage sloped dual-screen separator showed the highest average TS and VS removal efficiencies, and methane emission potential reduction of 52.5%, 59.7%, and 55.8%, respectively. The 1-stage horizontal scraped screen separator had the lowest TS and VS removal efficiencies, and methane emission reduction potential of 6.3%, 9.3%, and 4.9%, respectively. The results have potential implications for nutrient and greenhouse gas management strategies and/or policies in agriculture. Keywords: Greenhouse gas, Lagoon, Manure management, Separation efficiency, Settling basin, Solid-liquid separation, Sustainable agriculture.