Manure Moisture Research Articles

Rapid acquisition method of discrete element parameters of granular manure and validation

It is not easy to obtain the numerical simulation model of organic fertilizer quickly and accurately due to the wide range of moisture content of machine-applied bulk manure. This paper proposes a method of obtaining discrete element simulation parameters by measuring bulk manure's moisture content according to the two edge contours of the stacking angle and the image processing method to reduce the measurement error. With Hertz-Mindlin with JKR as the model, the Plackett-Burman test is used to screen the DEM parameters that significantly impact the simulation test's stacking angle. The Climbing and Box-Behnken tests establish a prediction model for the stacking angle of moisture content and DEM parameters. The funnel and probe methods are used to verify the stacking angle of manure. The comparison results showed that the average relative error is less than 4.30%. The mechanical properties' comparison test shows that the Displacement-Load change trend is consistent, and the average relative load error is 12.1%. The validation results of the manure box indicate that the average torque error is 11.73%. The above results show that the prediction model established is stable and reliable. By measuring the moisture content, the DEM parameters of granular manure can be quickly obtained, improving fertilization machinery's design and optimization efficiency.

Modeling and experimental studies on chemical absorption of ammonia emitted from poultry manure during the drying process by a wet spray scrubber: Optimization by Box-Behnken design

One of the most important environmental worries related to poultry production is ammonia gas emission which is affected by poultry manure moisture. This research was aimed at investigating poultry manure drying in a hot air dryer and its influence on ammonium nitrogen losses to provide an overview of ammonia gas emissions and absorption of emitted ammonia by a spray scrubber. The effect of air temperature (60–80 °C), air relative humidity (8–18 %), manure depth (2–4 cm), and air velocity (2–3 m s−1) were analyzed to optimize the drying process. The optimization of ammonia absorption involved analyzing the effects of absorbent solution temperature (30–50 °C), solution pH (2−4), and nozzle operating pressure (0.2–0.6 Mpa). The Box–Behnken design was applied to optimize these processes. Manure depth was the factor that had the most significant effect on both drying duration and ammonia emission (ammonium nitrogen losses). during the drying process, the ammonium nitrogen losses increased with increasing the manure depth and decreasing the air velocity and air temperature. The optimum ammonium nitrogen was 570,330 mg h lit−1 at an air temperature of 60 °C, air relative humidity of 8.11 %, manure depth of 3.95 cm, and air velocity of 2 m s−1. Both the temperature of the absorbent solution and the solution pH had opposite effects on the ammonia absorption. Increasing nozzle operating pressure increased ammonia absorption. The maximum ammonia absorption was obtained at a solution temperature of 49.2 °C, solution pH of 2, and nozzle operating pressure of 0.58 Mpa. At these conditions, the amount of ammonium sulfate in the absorbent solution was 9.09 g lit−1 and the efficiency of the spray scrubber was 66.79 %. So, we can be sure that ammonia emission from poultry manure and the absorption of emitted ammonia can be controlled by varying the investigated variables.

Ammonia Emissions from Cattle Manure under Variable Moisture Exchange between the Manure and the Environment

When reducing ammonia emissions from cowsheds, it is recommended to reduce the ventilation intensity, air temperature in the barn, manure moisture by using bedding and manure-contaminated surfaces, and to prevent urine from accumulating in the airways. Using the mass flow method in the wind tunnel, after research on seven types of cattle manure with different moisture contents, it was found that ammonia evaporates up to 3.9 times more intensively from liquid manure than from solid manure. There is a strong correlation between ammonia and water evaporation from manure. Ammonia emission from liquid manure decrease by 2.0–2.3 times, emissions from solid manure decrease by 1.9–2.1 times. Different cowsheds have different opportunities to reduce air pollution and conditions for manure to dry and crusts to form on the surface. The best results will be achieved by applying complex measures to reduce air pollution.

Nutritional profiling reveals the effects of dietary zeolite on Asian seabass Lates calcarifer

As costs for nutrition in aquaculture farming escalate, using affordable feeds that provide an optimal combination of nutrients for the fish species of choice is paramount. Natural zeolites have been applied in aquaculture as early as 1977 including feeds in animal nutrition, and moisture and ammonia control of animal manure. In this study, five experimental diets: control, Z1, Z2, Z4 and Z8 containing 0, 1, 2, 4 and 8% of dietary zeolite respectively were investigated for growth performance and immune responses in Lates calcarifer. In general, dietary zeolite supplementation boosted overall growth performance, particularly with Z4 of 4% zeolite supplementation showing the highest Body Weight Gain (BWG) over the other diets. Feed Conversion Ratios (FCR) and Protein Efficiency Ratio (PER) of fish were found to be significantly improved (P < 0.05) by the supplementation of zeolite. Furthermore, no significant changes in the immune and stress responses of fish at both 4% and 8% zeolite supplementation were exhibited, indicating that the presence of zeolites did not impair the immune state of L. calcarifer. This study suggests the suitability of dietary zeolite supplementation and recommends 4% zeolite supplementation to be the most ideal for improved growth performance for L. calcarifer.

Estimation of Japanese Black Calf Manure Moisture and Possibility of Classifications of Manure Score using Deep Learning

ウシの糞は体調判別用にスコア化され，写真例や外見的特徴を参考に目視で判定されている．しかし，この糞スコアの基準には曖昧な点が多く，糞水分に関する報告が少ない．本研究では家畜管理者の負担軽減と技能習得を容易にするため，体調判定の基本となるウシの糞水分を数値化し，深層学習による人工知能で糞水分を推定して糞スコアを分類する手法を検討した．実験は黒毛和種育成牛から糞を採取して糞水分を測定し，深層学習を使用した物体検出技術による糞水分を基にした糞スコアの分類精度を検証した．糞水分は75.7～93.8％となり，糞水分89～91％では広がり度合いが大きくなった．糞水分92～94％では糞が液状のため，敷料（籾殻）の下に隠れるような形となった．糞スコアは3段階が糞水分6％，4段階が5％，5段階が4％，6段階が3％の間隔でそれぞれ区分して設定し，AIモデルを作成した．作成したAIモデルのF値は3段階のモデルが0.80，4段階のモデルが0.73，5段階のモデルが0.62，6段階のモデルが0.53であり，3段階および4段階で分類するモデルが5段階および6段階で分類するモデルよりF値が有意に高くなった．このことから，深層学習を使用して糞スコアを分類する場合には，3段階または4段階での分類が有効であると考えられる．

Characterizing manure drying practices in Iowa commercial egg production facilities

As laying hen housing styles change throughout Iowa to meet legislative and consumer demands, drying of manure can be economically expensive and energy intensive. With about 50% of total electricity consumption and about 60% of annual electricity costs attributed to manure drying, this represents an opportunity for producers to decrease production costs while reducing electrical grid strain. To understand current practices and potential opportunities, survey data were collected from 34 Iowa egg producers in fall 2020, representing egg-laying ( n = 50), breeding ( n = 30), and rearing ( n = 20) facilities. Average (± SD) reported number of weekly manure removal events was 2.2 ± 0.50 for all housing styles with 2.4 ± 0.09 for cage-free aviaries and 2.2 ± 0.58 for conventional cage. Reported daily manure blower operation was 14.2 ± 11.0 h/d for all facilities, with cage-free aviaries operating blowers for 10.0 ± 11.8 h/d while conventional cage houses operated blowers for 15.1 ±10.8 h/d. On a per thousand bird basis, reported overall energy usage was 10.1 kWh per day, 308 kWh per month, and 3.7 MWh per year. Energy costs per thousand birds were US$0.81 per day, US$25 per month, and US$296 per year. Respondents from 16 facilities reported their facility did not have smart meters (i.e., monitoring voltage, current, power factor, and energy consumption), while 10 reported smart meter usage and 5 reported they were unsure. Managers were no more likely to be aware of facility peak demand or track peak demand regardless of whether the facility had a smart meter (aware: P = 0.09; track: P = 0.26). Interestingly, all 21 respondents reported being aware of peak demand incentives; however, only 9 (43%) respondents indicated their facilities participate in these incentives. These results provide a characterization of manure drying practices and energy usage in Iowa egg production facilities. There are opportunities to impact the manure drying process through control strategies that optimize blower energy based on environmental conditions, target manure moisture content, and peak demand periods.

Controlling dairy manure moisture content during composting by mixing the manure with wheat straw reduces greenhouse gas emissions

Controlling dairy manure moisture content during composting by mixing the manure with wheat straw reduces greenhouse gas emissions

Cantenna Adjustment with 1x6 Woodpile Shaped EBG for Application in Goat Manure Moisture Content and Bulk Density Monitoring

Cantenna Adjustment with 1x6 Woodpile Shaped EBG for Application in Goat Manure Moisture Content and Bulk Density Monitoring

Substantiation of optimum relative humidity of slurry when applying the batch-type gravity flow system for its removal

The batch-type gravity flow system for slurry removal is most commonly installed on the new and reconstructed pig farms. The newly designed system is characterized by the presence of plastic sewing pipes under each slurry-collecting canal. Such a system allows for complete automation of slurry removal and, under proper operation, mitigates the negative impact of pig farms on the environment through the lower annual output of slurry. The paper presents the calculation of the main design parameter of the system, such as the depth of slurry pits and the burial depth of longitudinal and transverse slurry collectors. Under the increase of pig manure humidity from 88% to 90%, the height of the residual layer decreases owing to lower manure shear stress in the part, where the manure moisture content increases. Under the relative humidity above 91%, the height of the residual layer in the pit increases rapidly due to the intensive stratification of slurry into fractions. Thus, the minimum height of the residual layer in the pit is achieved at the relative moisture content of 89-91%. Slurry should be accumulated in the pits to the 3/4 or 4/5 of the height (depth) of the pit. The accumulation period must be a multiple of the operating cycles of housing of various age and gender groups of pigs.

Particulate matter emissions during field application of poultry manure - The influence of moisture content and treatment.

Along with industry and transportation, agriculture is one of the main sources of primary particulate matter (PM) emissions worldwide. Bioaerosol formation and PM release during livestock manure field application and the associated threats to environmental and human health are rarely investigated. In the temperate climate zone, field fertilization with manure seasonally contributes to local PM air pollution regularly twice per year (spring and autumn). Measurements in a wind tunnel, in the field and computational fluid dynamics (CFD) simulations were performed to analyze PM aerosolization during poultry manure application and the influence of manure moisture content and treatment. A positive correlation between manure dry matter content (DM) and PM release was observed. Therefore, treatments strongly increasing the DM of poultry manure should be avoided. However, high manure DM led to reduced microbial abundance and, therefore, to a lower risk of environmental pathogen dispersion. Considering the findings of PM and microbial measurements, the optimal poultry manure DM range for field fertilization was identified as 50-70%. Maximum PM10 concentrations of approx. 10mg per m3 of air were measured during the spreading of dried manure (DM 80%), a concentration that is classified as strongly harmful. The modeling of PM aerosolization processes indicated a low health risk beyond a distance of 400m from the manure application source. The detailed knowledge about PM aerosolization during manure field application was improved with this study, enabling manure management optimization for lower PM aerosolization and pathogenic release into the environment.

Techno-economic and environmental assessments for nutrient-rich biochar production from cattle manure: A case study in Idaho, USA

Bioproducts from biomass feedstocks and organic wastes have shown great potential to address challenges across food-energy-water systems. However, bioproducts production is at an early, nascent stage that requires new inventions and cost-reducing approaches to meet market needs. Biochar, a byproduct of the pyrolysis process, derived from nutrient-rich biomass feedstocks (e.g., cattle manure and poultry litter) is one of these bioproducts that has numerous applications, such as improving soil fertility and crop productivity. This study investigates the market opportunity and sustainability benefits of converting manure to biochar on-site, using a portable refinery unit. Techno-economic and environmental impact assessments are conducted on a real case study in Twin Falls, Idaho, USA. The techno-economic analysis includes a stochastic optimization model to calculate the total cost of biochar production and distribution. The environmental study employs a life cycle assessment method to evaluate the global warming potential of manure-to-biochar production and distribution network. The total cost of biochar production from cattle manure near the feedlots is approximately $237 per metric ton, and total emission is 951 kg CO2 eq. per metric ton. The on-site operation and manure moisture content are two key parameters that can reduce biochar unit price and carbon footprint of manure management. It is concluded that converting cattle manure, using the presented strategy and process near the collection sites can address upstream and midstream sustainability challenges and stimulate the biochar industry.

Environmental pollution caused by the manure storage

The purpose of this work was to compare the quality indicators of manure with different ways of its removal and storage for pollution of the environment. The research was carried out at three farms with different variants of removal, storage and processing of manure: using deep, unchangeable for a long time straw litter, processing of manure in a bioreactor-fermenter and sedimentation in open-air lagoons. By the amount of NPK content per 1 kg of fertilizer, the highest rates were observed for the deposition on the deep litter – 7.69 g. The least of these elements was in the fertilizer obtained as a result of storage in the lagoon – 6.16 g. At the variant of manure processing in the bioreactor-fermenter intermediate indicators – 6.69 g were observed. The highest manure moisture index was for storage in the lagoon – 17.71% and 1.38% more compared with the option on deep litter and bioreactor-fermenter. The lowest amount of weed seeds was deposited on deep litter – 79 units/ml, which is 24 and 38 units/ml more than for processing in a bioreactor-fermenter and storage in the lagoon. The indicator of germination of weeds, which is very important in terms of the future use of manure in organic fertilizers, in general, for all variants of storage (processing) had positive indicators. The germination index of weeds under storage on deep litter was 5.72%, which is 3.14 and 4.42% less than by processing in a bioreactor-fermenter and in a lagoon. The largest emissions of N2O (nitrogen oxide) were 40712.45 kg at manure storage in the lagoon, which is 39781.88 kg more than at the variants of deep-litter storage and bioreactor-fermenter.

Development of an indented cylinder metering device for a tractor drawn manure spreader

The research work was carried out to develop an indented cylinder metering device for a tractor drawn manure spreader capable of transporting, metering and uniform spreading of the manure in the farm. Materials of right strength and sizes for the equipment parts were determined and selected based on the design analysis and calculations carried out. Hopper, manure metering system, floor wheels, energy transfer system, machine frame and gear system are the main components of the machine. The equipment was tested using three factors; number of grooves, speed and the manure moisture contents while the response is spreading efficiency. The metering system used are 1, 2, 3 and 4 grooves, and the speed was varied at four levels of 8 km/hr, 13 km/hr, 18 km/hr, and 23 km/hr. The manure moisture content was varied at 8%, 12%, 16% and 20% (d.b). The test outcomes of the equipment using cow dung, the largest manure delivery efficiency of 82% was achieved from a velocity of 23 km/h using a metering cylinder with four grooves, whereas a minimum efficiency of 48% was achieved from a velocity of 8 km/h using a single groove metering cylinder. Also highest manure delivery efficiency of 85% was obtained from manure with 8% moisture content (db) while least efficiency of 63% moisture content was obtained from manure with 20% moisture content (db). The efficiency of manure delivery improved with both tractor speed and amount of metering groove but reduced with enhanced humidity content of manure. The three parameters therefore have important impacts on the efficiency of manure delivery. The throughput capacity of the equipment is 11 hectares per day. It is anticipated that the development of this equipment will decrease human drudgery, reduce accumulation of manure in the soil and improve application uniformity and enhance the productivity of the farmer.

Losses of Solids, Moisture, Nitrogen, Phosphorus, Potassium, Carbon, and Sulfur from Laying-Hen Manure in Storage Facilities

The losses of total solids, moisture, nitrogen (N), phosphorus (P), potassium (K), carbon (C), and sulfur (S) were determined in two storage events of laying-hen manure immediately removed from three different housing systems in Iowa, USA. The three laying-hen houses were conventional cage (CC), enriched colony (EC), and aviary (AV). The houses held a nominal number of 200,000, 46,700, and 50,000 Lohmann LSL lite layers, respectively. The manure collected on belts in each house was cleaned out twice a week. A fraction of the cleaned out manure was transferred to designated storage rooms wherein losses of different components were determined in two storage events. Manure was loaded into the storage rooms over 171 days during the first storage event and over 185 days during the second storage event. The total storage periods were 202 and 245 days, respectively, for the first and second storage events. Manure was weighed, sampled, and analyzed before it was loaded into the storage rooms and at the end of each storage event. Mass balance calculations were used to determine the losses of different components. Statistical analyses show that the nutrient contents, on a wet basis, of manure loaded in CC, AV, and EC storage rooms were significantly different due to the differences in manure moisture contents. However, on a dry basis, they had no significant differences. The fresh manure cleaned out from the EC layer house was drier than that from the other two houses. Loaded-in nitrogen losses in the CC, AV, and EC storage rooms were 24.6, 12.9, and 20.8%, respectively. Nitrogen losses depended on house temperature, manure moisture, and pH. The average losses of loaded-in manure mass, moisture, and total solids during the two storage events were 27.6 ± 1.9, 33.8 ± 8.3, and 20.8 ± 7.0%, respectively. The losses of N, P, K, C, and S were 19.4 ± 13.4, 11.7 ± 5.6, 10.2 ± 6.8, 27.0 ± 6.5, and 8.3 ± 8.5% of their loaded-in amounts, respectively. The total loss of N, P, K, C, and S was 56% of the total loaded-in solids loss; thereof, the loss of N, P, and K was 7%, and C loss was 48%. The laying-hen-specific losses of N, P, K, C, and S were 0.34, 0.05, 0.08, 3.2 and 0.019 g day−1 hen−1, respectively. The results of this research are important for assessing impacts of stored manure on environment and nutrient losses. They can also be used to develop methodologies for the mitigation of the emissions from egg production facilities.

Identifying the Primary Limiting Factors of Pig Manure for Biogas Production

The present study was undertaken to analyze the primary limiting factors of pig manure for biogas production. Eight numbers of fresh pig manure samples were collected for primary compositions and the data were analyzed and reasons for poor biogas production probability were ascertained after comparing pig manure with cattle dung composition. The moisture, total solid and volatile solid percentage of fresh pig manure was 79.27%, 19.73% and 82.04% respectively. The ash, crude fiber and ether extract percentage were 17.96, 13.96 and 4.45 respectively. The C:N ratio in pig manure was 14:1. The ammonical nitrogen was 2.58% in fresh pig manure and it was 25 % of total nitrogen estimated on total dry mater basis, which was quite higher side for biogas production. The pH of fresh pig manure was slight acidic (6.73) which is in the range of desirable range pH for optimum biogas production, i.e. 6.5 to 7.5. The microbial consortia in fresh manure were detectable in terms of TBC and E. coli, where as no salmonella and salmonella like organism was found in fresh pig manure. Comparing the compositional values in between cow dung and pig manure major shortfall was found in terms of C: N ratio, ammonical nitrogen and pH in pig manure for efficient biogas production, which are the major primary limiting factors in pig manure, which needs to be conditioned with suitable techniques of carbonization, dilution and acidification respectively for efficient biogas production.

Evaluation of some effective parameters in performance of a helical two-sided manure distributor

Organic manures play an important role in improvement of soil fertility, increasing of crop yield and quality. The beneficial advantages of manure depend firstly on the method of spreading. Usually current manure spreaders cannot broadcast manures with different moisture contents and have non-uniform application rate. So the main objective of this research is performance evaluation of a new helical two-sided manure distributor that would be capable to spread manure at different moisture contents with long distribution width in uniform patterns. Experimental evaluation of the machine performance at two moisture content of manure in three forward velocities and three rotational speeds of drum showed that the moisture content of manure and rotational speed of drums had significantly effects (p = 0.01) on the distribution width and uniformity of the distribution pattern. The maximum distribution width of the machine at moisture content of 23% w.b. and 54% w.b. and in 1000 rpm rotational speed of drum were 19.3 m and 23.3 m respectively. Results indicated that the manure distribution uniformity increased by increasing the manure moisture and the distribution pattern of machine has an acceptable correlation with oval distribution pattern (p = 0.05).

Nitrogen mineralization of bioslurry and other manures in soil

The experiment was conducted to examine the nitrogen (N) mineralization pattern of bioslurry and other manures under aerobic and anaerobic soil conditions. Two bioslurries (cowdung and poultry manure) and their original manures (cowdung and poultry manure) @ 3, 5, 10 and 20 t ha-1, respectively, were thoroughly mixed with soil and incubated in aerobic and anaerobic moisture condition for 12 weeks and available N (both NH4+-N and NO3--N) was measured by steam distillation method. NO3--N was the dominant form of inorganic N in aerobic soil, whereas, NH4+-N dominated under anaerobic soil condition. When highest cumulative total available N mineralization among the manures at 3, 5, 10 and 20 t ha-1 rate was considered after 12 weeks of incubation, the N mineralization was 5.0, 5.5, 6.8 and 4.3 times higher, respectively, in aerobic condition over anaerobic condition. Under aerobic condition cowdung bioslurry and poultry manure bioslurry had very closer percentage of N mineralization and was much higher compared to their original manure (cowdung and poultry manure, respectively). With the increase of the rate of manure application, total available N release was increased but percent N release was rather decreased irrespective of the types of manure and soil moisture contents. Application of bioslurries in parallel with their original manures (cowdung and poultry manure) in soils are, therefore, should be considered and recommended to increase N fertility in soil.Res. Agric., Livest. Fish.2(2): 221-228, August 2015

Onsite and online FT-NIR spectroscopy for the estimation of total nitrogen and moisture content in poultry manure

The nitrogen and moisture of manure are highly variable parameters and depend on animal type, husbandry techniques, environmental conditions and storage time. The precision in manure dose estimation for crops fertilization depends on the total nitrogen and moisture content just before its incorporation in the field. The aim of the study is to develop a Fourier Transform Near Infrared (FT-NIR) spectroscopy method to determine the total Kjeldhal nitrogen (TKN%) and moisture (M%) of different types of poultry manure prior to land application. Samples covering a wide range of poultry types and different husbandry conditions were obtained from farms of North-Eastern Italy in order to develop the method. The method was calibrated (R2 = 0.94 for TKN%, R2 = 0.99 for M%) and validated (R2 = 0.82 for TKN%, R2 = 0.95 for M%) in the laboratory. An external validation was also performed in situ with independent samples, of similar origin to the previous data set, which were collected just before application in the field. Spectra acquisitions for these samples were carried out using the same instrumentation which was placed in a special vehicle for monitoring campaigns. The results showed satisfactory prediction accuracy (R2 = 0.82 for TKN%, R2 = 0.93 for M%). Finally, an additional analysis was performed to discriminate the different types of poultry effluents. The TKN and M measurements in the disposal areas indicated that current agronomic practices lead to more than double poultry manure oversupply. The proposed FT-NIR methodology aims to improve the current fertilization management and environmental protection by providing fast and precise estimations of poultry manure doses prior to land application.

COMPOSTAGEM COMO ALTERNATIVA DE DESTINAÇÃO PARA O LODO FLOTADO DE ABATEDOURO DE FRANGOS

Any human activity leads to the production of waste , however society requires continuous maintenance and improvement of environmental conditions , where various techniques of recycling or waste processing can be used . One technique that has been widely employed is composting , where biological degradation , aerobic or anaerobic organic waste in order to produce a humic substance to condition the soil occurs . The chicken slaughterhouses constitute major sources of pollution generators mainly of water . Thus this paper describes the application of composting as a means of disposal of sludge generated in wastewater treatment of a poultry slaughterhouse . Three different treatments were applied and evaluated some parameters such as temperature , odor , flies , ants , larvae in the windrow , and larvae in manure and manure moisture, pH , nitrogen, phosphorus , carbon and potassium. The results were satisfactory , with its particularities for each parameter in the positive and negative aspects.

Housefly maggot-treated composting as sustainable option for pig manure management

In traditional composting, large amounts of bulking agents must be added to reduce the moisture of pig manure, which increases the cost of composting and dilutes the N, P and K content in organic fertilizers. In this study, maggot treatment was used in composting instead of bulking agents. In experiment of selecting an optimal inoculum level for composting, the treatment of 0.5% maggot inoculum resulted in the maximum yield of late instar maggots, 11.6% (maggots weight/manure weight). The manure residue became noticeably granular by day 6 and its moisture content was below 60%, which was suitable for further composting without bulking agents. Moreover, in composting experiment with a natural compost without maggot inoculum and maggot-treated compost at 0.5% inoculum level, there were no significant differences in nutrient content between the two organic fertilizers from the two treatments (paired Student’s t15=1.0032, P=0.3317). Therefore, maggot culturing did not affect the characteristics of the organic fertilizer. The content of TNPK (total nitrogen+total phosphorus+total potassium) in organic fertilizer from maggot treatment was 10.72% (dry weight), which was far more than that of organic fertilizer made by conventional composting with bulking agents (about 8.0%). Dried maggots as feed meet the national standard (GB/T19164-2003) for commercial fish meal in China, which contained 55.32±1.09% protein; 1.34±0.02% methionine; 4.15±0.10% lysine. This study highlights housefly maggot-treated composting can be considered sustainable alternatives for pig manure management to achieve high-quality organic fertilizer and maggots as feed without bulking agents.