Manure Treatment Research Articles

Dairy manure influences soil properties, plant nutrient uptake, and tuber quality in potatoes

AbstractDairy manure applications are a common practice in Idaho potato (Solanum tuberosum L.) production, however the impacts on tuber yield and quality are not well understood. Our objectives were to determine (1) how repeated dairy manure applications impact soil properties and plant nutrient uptake, and (2) how these changes influence plant nutrient interactions, tuber yield, and quality. Stockpiled dairy manure was fall‐applied over a 6‐year period to two adjacent potato production fields in Kimberly, ID. Eight treatments included application frequency (annual and biennial), manure application rate (18, 36, and 52 Mg ha−1 application−1 [dry weight basis]), fertilizer‐only, and a non‐amended control. Manure treatments were supplemented with fertilizer to prevent nutrient‐limiting conditions. Compared to fertilizer treatments, mean soil organic matter, total N, and K were greater for annual manure by 53%, 47%, and 426%, and biennial manure by 24%, 23%, and 199%, respectively. For annual applications only, mean soil nitrate, P, and electrical conductivity were greater than fertilizer treatments by 247%, 431%, and 222%, respectively. Manure promoted P and K luxury consumption with increasing application rate and frequency. Foliage Ca, Mg, Zn, Mn, and Cu correlated negatively against foliage K, potentially due to cation competition and translocation disruption. Annual applications decreased mean tuber specific gravity from 1.078 to 1.073, which may be attributed to saline‐sodic conditions and delayed maturity from late‐season N mineralization. Our findings suggest that biennial manure applications may prevent specific gravity issues. Agronomic parameters related to N, K, and soluble salts should be closely monitored in these systems.

Firmicutes primarily drive odor emission profiles in poultry manure treatments

Odor emission during livestock manure treatment poses a threat to the environment and human health. However, the odor emission profiles and related factors of commonly employed poultry manure treatments have rarely been studied. Here, we explored the odor emission profiles of 3 common poultry manure treatments in China, namely, ectopic fermentation beds (EFB), annular composting troughs (ACT) and air-drying rooms (ADR). The results revealed that the total odor concentrations in the EFB, ACT and ADR groups were 2407.67 ± 512.94, 13444.00 ± 1269.92 and 621.33 ± 59.27, respectively. The ACT had the greatest number of odorants (31), followed by the ADR (27) and the EFB (24). Methyl mercaptan, acetic acid, acetaldehyde, hydrogen sulfide, ammonia and acrolein were the key odorous compounds detected in all the treatments. ACT contained the greatest number of key odorants (11) and exhibited an extensive co-occurrence relationship with the bacterial community. The 3 poultry manure treatments exhibited significant differences in the beta diversities of the bacterial community. The phylum of most bacteria associated with key odorants was Firmicutes, and Enterococcus and Oceanobacillus were significantly positively correlated with methyl mercaptan. The bacterial functional groups were enriched in carbohydrate metabolism, amino acid metabolism and energy metabolism, and the functional genes shaped the odor emission patterns in the poultry manure treatments. Redundancy analysis demonstrated that odor emission in the 3 treatments was positively correlated with Firmicutes abundance, pH, electrical conductivity and moisture. Thus, our study provides a good understanding of odor emission profiles in poultry manure treatments and data for precise odor emission control during livestock production.

Optimized removal of silica during manure treatment by electrocoagulation-flotation (EC-F) in view of fouling prevention of reverse osmosis membranes

Reverse osmosis (RO) membrane fouling threatens the performance of manure treatment. In this regard, silica is considered one of the most challenging inorganic foulants. Removing silica fouling from RO membranes is difficult, ultimately leading to performance deterioration, including reduced permeability and premature membrane failure. This study examines the removal of silica during manure treatment using a novel tubular electrocoagulation-flotation (EC-F) reactor with an Al electrode. The EC-F was positioned between an ultrafiltration and a RO membrane filtration system. The operational parameters—current density, electrolysis residence time, and initial pH—were optimized for maximum silica removal efficiency and minimum operational cost. At the optimum conditions (pH of 8.2, current density of 160 A/m2 and electrolysis residence time of 23 s), 88 % of silica (initial concentration of 104 mg/L) was removed. Subsequent membrane fouling assessment revealed that EC-F pretreatment decreased the fouling potential by 28 % (from 7.11 × 1016 to 5.10 × 1016 Pa·s/m2·t), indicating efficient foulant removal. SEM-EDX analysis of the membrane confirmed the lack of scale formation when using EC-F pretreated manure as a feed stream. This study demonstrates that the use of innovative EC-F pretreatment significantly reduces the operational expenditure (1.75 €/m3) compared to prior EC-F research for silica removal from manure, thereby reducing the fouling of RO membranes.

The Crop Phosphorus Uptake, Use Efficiency, and Budget under Long-Term Manure and Fertilizer Application in a Rice–Wheat Planting System

Little is known about the effect of the long-term application of organic and inorganic fertilizers on P-use efficiency, P budget, and the residual effect of P fertilizer. To clarify the effect of different fertilization on soil P balance in a rice (Oryza sativa L.)–wheat (Triticum aestivum L.) rotation system is helpful to promote the sustainable development of agriculture. Thus, a thirty-five-year fertilizer experiment was conducted with eight treatments, including an unfertilized control (CK); chemical nitrogen (N), phosphorus (P), and potassium (K) fertilizers; and organic manure (M) either alone or in combination treatments (N, NP, NPK, M, MN, MNP, and MNPK). The results indicated that crop yields and P uptake were higher in the combined application of manure and chemical fertilizer treatments than in the manure or chemical fertilizer alone treatments. Soil P budget indicated a 23.4–55.4 kg P ha−1 yr−1 surplus in the organic combined with or without mineral fertilizer treatments, but the soil P budget indicated a 20.0 and 21.9 kg P ha−1 yr−1 deficit in the control and N treatments. The proportion of residual fertilizer P converted to soil available P in NP, NPK, M, MN, MNP, and MNPK treatments was 4.5%, 4.8%, 19.1%, 19.0%, 11.5%, and 13.3%, respectively, over a 35-year period. Furthermore, according to the higher P content and crop uptake in organic manure treatment compared with chemical P fertilizer alone, an organic addition could effectively reduce the use of chemical fertilizer and become an effective way of sustainable development in practice. Therefore, the combined application of organic and inorganic fertilizer will be a practical method to increase crop yields and soil P status in a rice–wheat planting system.

Core Bacterial Taxa Determine Formation of Forage Yield in Fertilized Soil.

Understanding the roles of core bacterial taxa in forage production is crucial for developing sustainable fertilization practices that enhance the soil bacteria and forage yield. This study aims to investigate the impact of different fertilization regimes on soil bacterial community structure and function, with a particular focus on the role of core bacterial taxa in contributing to soil nutrient content and enhancing forage yield. Field experiments and high-throughput sequencing techniques were used to analyze the soil bacterial community structure and function under various fertilization regimes, including six treatments, control with no amendment (CK), double the standard rate of organic manure (T01), the standard rate of organic manure with nitrogen input equal to T04 (T02), half the standard rate of inorganic fertilizer plus half the standard rate of organic manure (T03), the standard rate of inorganic fertilizer reflecting local practice (T04), and double the standard rate of inorganic fertilizer (T05). The results demonstrated that organic manure treatments, particularly T01, significantly increased the forage yield and the diversity of core bacterial taxa. Core taxa from the Actinomycetota, Alphaproteobacteria, and Gammaproteobacteria classes were crucial in enhancing the soil nutrient content, directly correlating with forage yield. Fertilization significantly influenced functions relating to carbon and nitrogen cycling, with core taxa playing central roles. The diversity of core microbiota and soil nutrient levels were key determinants of forage yield variations across treatments. These findings underscore the critical role of core bacterial taxa in agroecosystem productivity and advocate for their consideration in fertilization strategies to optimize forage yield, supporting the shift towards sustainable agricultural practices.

Experimental study on the performance of enhanced air-cooled photovoltaic thermal energy-supplied manure treatment technology

Implementing renewable energy technologies for manure treatment to reduce energy consumption and environmental damage is steadily becoming more prevalent. In this work, an air-cooled photovoltaic thermal (PV/T) device was enhanced and constructed to provide energy for bio-composting manure treatment. Experiments were conducted to analyze the performance data such as air supply temperature, energy and exergy efficiency, and mass flow rate. When calculating the mass flow rate of the PV/T-supplied manure treatment technology, factors such as exergy efficiency, and hot air temperature must be considered. The results of the study indicate that the thermal performance of the developed equipment is adequate for manure composting treatment. The thermal exergy efficiencies of the V2, V3, and V4 cases are approximately 1/3 greater than the thermal exergy efficiency of the V1 case, indicating a considerable change in thermal efficiency. The mass flow rate of 0.020 kg/s is determined to be a more suitable set value. Its total exergy efficiency can reach 46.79%, and the apparatus could heat up to 43.63 kg/m2 of compost to begin the bio-composting process. This study lays the groundwork for future research and deployment of PV/T-powered manure treatment devices.

Effect of cyanobacteria biochar addition on humification, fungal dynamics and its mechanism of action in pig manure composting

Aerobic composting is an effective method for resourceful treatment of pig manure (PM). However, traditional composting often suffers from low humification effect and inactive fungal communities. In order to better treat PM, this study applied different doses of cyanobacterial biochar (CB) (T1:0 %; T2:2.5 %; T3:5 %; T4:7.5 %; T5:10 %; and T6:20 %) to PM composting and investigated the effects of biochar additives on the humification of PM composting and fungal communities. The results showed that biochar addition could prolong the thermophilic period (>50°C) by 1–4 days, with T4 being the most effective. Humification analysis showed that biochar increased the degradation of fulvic acid by 4.95–11.19 % and increased the formation of humic acid by 3.43–9.44 %, and final HA/FA ratio of T5 being the highest (2.44) compared to other treatments. The fungal abundance also confirmed that the addition of biochar significantly decreased the number of Ascomycetes at the maturation stage by 15.23 ∼ 89.23 % and increased the number of Basidiomycetes by 7.39 ∼ 119.54 times. Fungal community analysis showed that biochar could promote the birth of dominant fungi in the thermophilic phase and T5 had greater abundance of fungi than the other treatment groups. Network analysis indicated that high doses of CB (10–20 %) could enhance positive interactions among fungi to a greater extent. In conclusion, 10 % CB (T5) can optimize the compost quality to the greatest extent and has the highest application value.

Strategizing emissions reduction investment for a livestock production farm amid power demand pattern: A path to sustainable growth under the carbon cap environmental regulation

Livestock production companies come under increasing responsibility to reduce their environmental impact, and thereby, the simultaneous decision-making of inventory replenishment and emissions reduction investment has become essential for ensuring sustainable development in the livestock farming business. This study investigates, for the first time, the best investment strategy for a livestock farming business under the carbon cap (CC) environmental legislation, taking into account both the edible and non-edible parts of slaughtering mature growing items (GIs) after procuring and feeding baby GIs. By fusing economic and environmental factors, this study aims to shed light on two crucial issues: (i) figuring out the appropriate level of investment needed for the farm to adhere to the CC environmental regulation; and (ii) evaluating the effect of the investment decision on the farm's expenses and emissions levels. To deal with these insights, a thorough analytical framework integrating mathematical modeling methodology, economic evaluation, and carbon accounting approaches is employed. By analyzing the interaction between the farm's emissions reduction investments and replenishment choices, the cost-effective investment level is determined that enables the farm to satisfy the carbon cap obligation while guaranteeing maximum operational efficiency. The results of this study have important ramifications for livestock farming businesses trying to make their way through the stringent CC emission law. The results indicate that in order to keep the business feasible when the cap of the CC guideline is low, the livestock-producing farm should give priority to investing in minimizing feed emissions and using cutting-edge manure treatment methods.

Pengaruh Kombinasi Pupuk Kandang Sapi dan Pupuk NPK terhadap Pertumbuhan dan Hasil Tanaman Kubis (Brassica oleraceae L.)

The use of organic and inorganic fertilizers is an alternative way to get good cabbage production, one of which is by using cow manure and NPK. This study aims to determine the good use of a combination of cow manure and NPK fertilizer on the growth and yield of cabbage (Brassica oleraceae L.). The research was carried out from October 2022 to January 2023. This study used a Randomized Block Design (RAK), namely with a combination of cow manure (PKS) and NPK fertilizer. With the following details: P0 = Control, P1 = PKS 200 g + NPK 5 g, P2 = PKS 400 g + NPK 10 g, P3 = PKS 600 g + NPK 15 g, P4 = PKS 800 g + NPK 20 g. The treatments were repeated 3 times so that there were 15 experimental units. Each experimental unit used 5 polybags and each polybag was planted with one plant so that the total cabbage plants used were 75 plants. The variables observed were leaf area, time of crop formation, crop weight, and crop volume and root volume. The results showed that the combination of cow manure and NPK fertilizer had a significant effect on the growth of leaf area, crop weight, and crop volume. However, it has not had a significant effect on the time of crop formation. Treatment of cow manure 800 g + NPK 20 g (P4) fertilizer increased crop weight and crop volume. Treatment of cow manure 400 g + NPK 10 g (P2) fertilizer increased cabbage leaf area.

Manure application influences microbial stoichiometry and alters microbial life strategies to regulate phosphorus bioavailability in low-P paddy soil

Microbial stoichiometry is pivotal in the soil elements cycle within terrestrial ecosystems. However, the impact of microbial stoichiometry on the phosphorus (P) pool transformation in low-P paddy soil, especially with manure addition, remains poorly understood. This study aimed to elucidate the response mechanism of microbial stoichiometry in regulating P pool transformation in two low-P paddy soils during a 60-day flooding-drought incubation. The results demonstrated that pig manure and vermicompost application significantly increased soil Olsen-P by 202–309 %, and microbial biomass P (MBP) by 54.4–79.3 % compared to no fertilization. Additionally, vermicompost treatment increased moderately labile organic P (MLPo) by 133–257 % and decreased fulvic acidassociated organic P (FAPo) by 10.5–25.4 % in Acrisol-flooding, Acrisol-drought, and Ultisol-drought, indicating that manure application improved the transformation of FAPo to MLPo. The microbial biomass carbon (MBC)/MBP ratio was lowest under Acrisol-flooding and highest under Ultisol-drought, suggesting that microorganisms adjust high ratios for stoichiometric stability and enhanced MBP utilization under deficient resource conditions. Manure treatments increased alkaline phosphatase (ALP) by 5.33–12.9 % under flooding conditions, indicating microorganisms facilitate the mineralization of soil organic P (Po). Compared to Acrisol-flooding, both ALP and β-1,4-glucosidase (BG) significantly increased by 103 % and 259 %, respectively, under Ultisol-drought, along with a positive correlation between BG and MLPo, implying that microorganisms enhance soil organic matter mineralization in resource-limited conditions by increasing C-acquiring enzymes and releasing Po. Additionally, the microbial community composition shifted from r-strategists to K-strategists, primarily by decreasing Proteobacteria and increasing Acidobacteria under resource deficiency and drought. The r-strategists directly mineralize Po by maintaining a low MBC/MBP and high ALP, while K-strategists indirectly mineralize Po by maintaining a high MBC/MBP and high BG. The findings suggest that manure application altered the resource status of low-P paddy soils, changed microbial stoichiometry, and influenced soil P availability through adjustments in microbial activity and extracellular enzyme production.

The production of methyl mercaptan is the main odor source of chicken manure treated with a vertical aerobic fermenter

The process of harmless treatment of livestock manure produces a large amount of odor, which poses a potential threat to human and livestock health. A vertical fermentation tank system is commonly used for the environmentally sound treatment of chicken manure in China, but the composition and concentration of the odor produced and the factors affecting odor emissions remain unclear. In this study, we investigated the types and concentrations of odors produced in the mixing room (MR), vertical fermenter (VF), and aging room (AR) of the system, and analyzed the effects of bacterial communities and metabolic genes on odor production. The results revealed that 34, 26 and 26 odors were detected in the VF, MR and AR, respectively. The total odor concentration in the VF was 66613 ± 10097, which was significantly greater than that in the MR (1157 ± 675) and AR (1143 ± 1005) (P < 0.001), suggesting that the VF was the main source of odor in the vertical fermentation tank system. Methyl mercaptan had the greatest contribution to the odor produced by VF, reaching 47.82%, and the concentration was 0.6145 ± 0.2164 mg/m3. The abundance of metabolic genes did not correlate significantly with odor production, but PICRUSt analysis showed that cysteine and methionine metabolism involved in methyl mercaptan production was significantly more enriched in MR and VF than in AR. Bacillus was the most abundant genus in the VF, with a relative abundance significantly greater than that in the MR (P < 0.05). The RDA results revealed that Bacillus was significantly and positively correlated with methyl mercaptan. The use of large-scale aerobic fermentation systems to treat chicken manure needs to focused on the production of methyl mercaptan.

The Influence of Green Manure Planting on the Spectroscopic Characteristics of Dissolved Organic Matter in Freshwater-Leached Saline–Alkali Soil at Different Depths

This study investigated the influence of green manure planting on the spectroscopic properties of dissolved organic matter (DOM) in saline–alkali soil under freshwater leaching conditions at different soil depths. The UV254, UV253/UV203, α300, α355, SUVA254, SUVA260, and SR ultraviolet parameters indicated reductions in the content of large molecular substances, benzene ring substitution degree, colored dissolved organic matter, aromaticity, and hydrophobic components in the soil leachate DOM with an increasing soil depth. Compared with the non-green manure treatment control, green manure planting mitigated the leaching of dissolved organic matter in soil during saline irrigation, with rape green manure demonstrating superior effectiveness. Utilizing three-dimensional fluorescence combined with parallel factor analysis, this study analyzed three fluorescent components of soil leachate DOM: C1 (visible-light fulvic acid), C2 (humic acid), and C3 (tyrosine-like protein). The combined contribution of the two humic substance components (C1 + C2) was approximately 70%, indicating the dominance of humic substances in leachate DOM. The fluorescence parameters of soil leachate DOM included an average of the fluorescence index (FI) values between 1.4 and 1.9, low humification index (HIX) values consistently below 4, and biological index (BIX) values ranging from 0.8 to 1.0, suggesting a mixed source, low humification degree, poor stability, and moderate self-source characteristics. Compared with the non-green manure treatment control, both the green manure treatments exhibited a relatively higher proportion of biogenic sources and humification degree in soil leachate DOM. This suggests that planting green manure can reduce the relative DOM content under freshwater leaching conditions, increase the proportion of biogenic sources in soil leachate DOM, and enhance soil humification. Planting rapeseed green manure can diminish the leaching of DOM from land sources and augment soil humification.

Effects of farmyard manure (FYM) and blended NPSB fertilizer rate on growth and yield of potato (Solanum tuberosum L.) in Gewata, Kaffa, southwest Ethiopia

Potato (Solanum tuberosum L.) is an essential crop for nutrition and food security and generating income to small-holder farmers in Ethiopia. Productivity of the crop is, however, limited by poor nutrient management practices and low soil fertility. In most parts of potato growing areas of Ethiopia, soil are deficient in macro (nitrogen, phosphorus and sulfur) and micro nutrients (boron) which are known to affect production and productivity of potato. A field trail was accompanied to determine the growing response of potatoes ’Belete varieties’ to combine the treatment of farmyard manure and blended NPSB (nitrogen, phosphorous, sulfur and boron) fertilizer at Gewata, southwest Ethiopia during 2019/2020 main cropping season. The variables are laid out four level of farmyard manure (0, 5, 10 and 15 t/ha) and four level of blended NPSB fertilizer (0, 50, 100, and 150 kg/ha). The treatments were organized in a completely randomized block design with three replications using a 4x4 factorial layout. SAS (version 9.4) was used for data were analyzed. The finding indicate that, combined application of FYM (farmyard manure) with NPSB significantly (p&lt;0.01) affects plant height, average mass of tuber, number of marketable and unmarketable tuber per hill, and tuber yields per plot. It also significantly (p&lt;0.05) influenced days to flowering, maturity, and tuber number per hill. The highest tuber weight (99.33 g), tuber number per hill (9.67), and yield (34.10 kg) per plot were recorded from the mixed fertilization of 15 t FYM with 150 kg/ha NPSB mineral nutrients. As a current finding, it can be stated that the combined use of FYM (15 t/ha) and NPSB blended fertilizer could improve potato growth and yield in the study area (150 kg/ha).

Influence of Hydrothermal Carbonization (HTC) Temperature on Hydrochar and Process Liquid for Poultry, Swine, and Dairy Manure

Hydrothermal carbonization (HTC) is a promising technology for wet manure treatment by converting animal manure into valuable fuels, materials, and chemicals. Among other HTC process parameters, the temperature influences HTC products the most. As various animal manures have different compositions, it is not certain how the HTC temperature influences the hydrochar and HTC process liquid. To evaluate the temperature’s effect on HTC, three different manures (poultry, swine, and dairy) were hydrothermally carbonized at three different temperatures (180, 220, and 260 °C), and solid and liquid products were characterized for their morphology, elemental compositions, and ions. The carbon contents of the hydrochar reached as high as 38.98 ± 0.36% and 40.05 ± 0.57% for poultry and swine manure, respectively, when these manures were treated at 260 °C. Ammonium showed an around 30% increase in poultry manure hydrochar with the increase in the HTC temperature. In contrast, in swine manure, it decreased by around 80%, and in dairy manure, the HTC temperature did not have any remarkable effect on the ammonium content. The process liquids from HTC of dairy manure at 220 °C showed the most balanced distribution of different ions, with 4970 ± 673 ppm of sodium, 4354 ± 437 ppm of ammonium, 2766 ± 417 ppm of potassium, 978 ± 82 ppm of magnesium, 953 ± 143 ppm of calcium, 3607 ± 16 ppm of chloride, and 39 ± 7 ppm of phosphate. These results emphasize the manure-specific effects of the HTC temperature on both solid and liquid products, indicating the need for optimized strategies to enhance HTC processes for various types of animal manures.

Greenhouse gas emissions and nutrient use efficiency assessment of 6 New York organic dairies

Improving nutrient use efficiency and reducing GHG emissions are important environmental priorities for organic-certified dairy operations. The objectives of this research were to quantify annual nutrient use and GHG emissions in 6 organic New York dairy farms. Farm-gate nutrient mass balances (NMB) were estimated with the Cornell NMB calculator. Whole-farm GHG emissions were estimated using the Cool Farm Tool (CFT) and COMET. Farm-gate NMB were low, ranging from -6.5 to 19 kg N/ha for N1 (without legume N fixation), 26 to 71 kg N/ha for N2 (including N fixation), -2.4 to 8.2 kg P/ha for P, and 1.1 to 19.8 kg K/ha for K. Additional nutrient imports, coupled with nutrient management planning, adequate legume stands, and diet balancing may help improve P balances and ensure no N deficiencies in the system. Estimates of annual GHG emissions intensity ranged from 0.98 to 2.10 kg of CO2-equivalents (CO2-eq) per kilogram of fat- and protein-corrected milk (FPCM) estimated by CFT, and from 0.69 to 2.48 kg CO2-eq/kg FPCM estimated by COMET. Enteric fermentation, feed production, and fuel and energy use represented the largest sources of GHG. For farms with liquid manure storages, manure management was also a significant source. Estimates of soil carbon (C) stock changes from CFT were in agreement with or smaller than previous studies, and estimates from COMET were in agreement or greater. Variability and uncertainty in the results for soil C stock change indicate that more research and new protocols are needed. The effects of individual management changes on GHG emissions intensity were small, ranging from -8 to +7% in CFT, and -8% to +8% in COMET. The management changes that resulted in the largest reductions in GHG emissions intensity included increasing individual cow productivity and ratio of milk to total feed, and implementation of manure treatment systems.

Soil nematode community structure reaction to organic amendments in shallot

ABSTRACT Nematode abundance and diversity could indicate soil health since they play roles in the soil nutrient cycle. In a shallot field, nematode abundance and diversity from different types of organic manure treatment were examined to determine the effect of organic fertilizer on nematode abundance. This study aimed to determine the best option of organic amendment for managing the nematode population in crop soil. The research took place in the center of a shallot plantation in Kulon Progo District, Yogyakarta, Indonesia, and consisted of four treatments: cow manure+green manure; sludge+green manure; cow manure, and chicken manure as farmer control. The nematode community was processed and analised with the PCA, which indicated a cumulative value of 94.5%. The treatment of cow and green manure contributed in nematode abundance, in which nematodes clustered were predators, bacterial feeders, and omnivores. The treatment of cow and green manure could be the best option that environmentally friendly control plant-parasitic nematodes and improve beneficial nematodes abundance that could improve the soil health by their regulation in soil.

Treatment of swine manure by hydrothermal carbonization: The influential effect and preliminary mechanism of surfactants

Treatment of swine manure by hydrothermal carbonization (HTC) with the aid of different surfactants was first explored in this study. PEG 400 (polyethylene glycol 400) and Tween 80 facilitated the formation of bio-oil. SLS (sodium lignosulfonate) and SDS (sodium dodecyl sulfate) promoted the formation of water-soluble matters/gases. Span 80 enhanced the formation of hydrochar, which resulted in a 50.19 % mass yield, 92.39 % energy yield, and a caloric value of 28.68 MJ/kg. The hydrochar obtained with Span 80 presented a similar combustion performance to raw swine manure and the best pyrolysis performance. The use of Span 80 promoted the transfer of degradation products to hydrochar, especially hydrophobic ester and ketone compounds. Notedly, Span 80 suppressed the synthesis of PAHs during the HTC process, which was reduced to 0.92 mg/kg. Furthermore, the hydrochar produced with Span 80 contained lower contents of heavy metals. On the whole, Span 80 has shown great potential in enhancing the HTC of swine manure. The acting mechanisms of surfactants in the HTC of swine manure included adsorption, dispersion, and electrostatics repulsion.

The Effects of Different Combinations of Cattle Organic Soil Amendments and Copper on Lettuce (cv. Rufus) Plant Growth

In modern agricultural production, cattle manure waste recovery is considered as a sustainable approach to agricultural waste management, reducing environmental pollution and chemical fertilizer use. This study aimed to investigate the effects of manure and digestate derived from a pilot-scale livestock waste-recycling system, in combination with a low copper concentration as a fungicide, on the physiological response of lettuce cv Rufus (Lactuca sativa L.) plants and the associated soil microbiome. A five-week microcosm experiment was conducted in a greenhouse under environmental conditions. Lettuce plant performance was assessed in terms of biomass, leaf area index, photosynthetic activity, chlorophyll measurements, lipid peroxidation, total phenolic content, and nutrient uptake. The results suggested that incorporating digestate into the potting soil mix significantly enhanced crop yields compared to the control and manure treatments. The soil microbial activity increased in the presence of fertilizers, improving the soil chemical and biological properties. The addition of copper negatively affected the growth and physiological performance of the lettuce plants under both the control and manure-treated conditions, except for those grown in the presence of digestate, where copper accumulation was reduced. These findings highlight the potential of growing horticultural crops using organic fertilization through livestock waste anaerobic digestate, establishing a waste-to-food recycling system.

Research on the Composting Technology of Cattle and Sheep Manure Based on Intelligent and Efficient Composting Equipment and the Evaluation Standard of Decomposition Degree

The Inner Mongolia Autonomous Region is a crucial area in China with a significant advantage in animal husbandry, particularly in cattle and sheep farming. However, the disposal of the large quantities of manure produced during farming has severely impacted the industry’s healthy development. Proper treatment of the manure can convert it into organic fertilizer beneficial to farmland; otherwise, it will cause substantial environmental pollution. This study focuses on existing composting equipment and addresses the issues of cattle and sheep manure mixture ratios and compost maturity evaluation. Through experiments on the mixture of cattle and sheep manure, the optimal ratio for converting cattle and sheep manure into organic fertilizer was determined. Additionally, a fuzzy mathematical evaluation model was employed, along with experimental data, to establish a comprehensive evaluation system for aerobic compost maturity based on multiple indicators, revealing the variation patterns of maturity levels under different mixture ratios. The test results revealed that the composting equipment effectively controls the composting process, shortens the composting cycle, ensures the complete decomposition of organic matter, and meets national standards for livestock and poultry manure treatment. Regarding temperature and humidity, oxygen concentration, seed germination rate, pH value, electrical conductivity (EC), nitrogen, phosphorus, potassium content, and carbon-to-nitrogen ratio, the mixed compost of cattle and sheep manure in various ratios met the relevant standards for agricultural application. Various ratios of organic fertilizers containing cattle and sheep manure significantly promoted the growth of maize, wheat, and mung bean crops. Specifically, the compost decomposition cycle was shortest when sheep and cattle dung were mixed at a ratio of 2:1, while it was longest for all cattle dung. Finally, a fuzzy mathematical comprehensive evaluation model was established by selecting four indicators: water content, carbon-to-nitrogen ratio, apparent score, and germination index. The study demonstrates that the equipment and method offer significant advantages in efficiently treating cattle and sheep manure and producing organic fertilizer, thereby providing strong support for the sustainable development of animal husbandry.

Comparative investigation on composting and pyrolysis of swine manure: Heavy metals transformation, nitrogen immobilization and integrated environmental risk assessment

Harmless treatment of livestock manure has been a pressing issue due to its contamination of heavy metals and volatilization of nitrogen(N)-containing components during processing. In this paper, the chemical species transformation, leaching characteristics of Cr, Mn, Zn, Cu and conversion of amine N and inorganic N during composting and pyrolysis of swine manure (400°C, 500°C, 600°C and 700°C) were comparatively investigated, and their integrated environmental risk (η) was assessed. According to the ultimate and proximate analysis, pyrolyzed char exhibited better aromaticity and richer functional groups compared with that of compost; Cr, Mn, Zn, Cu were transformed into more stable residual states (F3+F4), and better inhibition of leaching in simulated landfill experiments was shown than compost. However, deamination and cyclocondensation reactions under higher pyrolysis temperatures resulted in N escaping in the form of NH3 and HCN. Considering various pollution coefficients, the integrated ecological risk was reduced by 59.24 % after 600°C pyrolysis, which is the optimal condition for the minimization of the risk of heavy metal toxicity and N volatilization among all the compost and pyrolysis process.