Mixture Of Manure Research Articles

Processing Horse and Cow Manure Waste in the Production of Fertilizer and Biogas at Flores Bajawa Agricultural College

Horses and cows have long been domesticated animals in Indonesia, one of which is at the Flores Bajawa Agricultural College. Horse and cow manure, which are solid waste products generated from metabolism, can generally pollute the environment, so they need to be processed. Therefore, it is necessary to conduct research on the utilization of horse and cow manure waste in the production of manure fertilizer and biogas. Manure is usually made from liquid or solid livestock waste mixed with food scraps, which will later function as humus. Biogas is a gas produced from organic waste such as animal and human manure stored in an airtight environment. The purpose of this research is to understand the utilization and processing of horse and cow manure waste into fertilizer and biogas. The methods used in this research are observation and experimentation. Fertilizer is made from a mixture of horse and cow manure. Meanwhile, biogas from horse and cow manure is produced with three treatments and various fermentation periods of 7, 14, and 21 days. One way to process horse and cow manure waste is to convert it into organic fertilizer and biogas. The fertilizer and biogas that have been produced are used to enrich agriculture and also as a source of fuel. The longer the fermentation time of the fertilizer and biogas, the better the nutrient content of the fertilizer and the greater the volume of gas produced in the biogas production process.

Application of a Mixture of Rabbit Fertilizer and Manure on Several Varieties of Chilli (Capsicum Frutescens L.) on Plant Growth And Yield

This research aims to obtain the best mixture of rabbit fertilizer with manure and the response to the best chili varieties. This research is a factorial experiment, with a basic randomized block design (RAK) with 2 factors being tried. The first factor with 3 levels: K 0 = no manure, K 1 = rabbit manure + cow manure, K 2 = rabbit manure + chicken manure. Second factor with 3 chili varieties: V1= Rawita, V2= Ori 212, V3= Caliber and repeated 3 times. K1 gave the highest value for the fresh weight of harvested fruit per plant, namely 250.63 g. The Caliber V3 variety gave the highest value for the fresh weight of harvested fruit per plant, namely 252.87 g.

Biochar from residues of anaerobic digestion and its application as electrocatalyst in Zn–air batteries

BackgroundBiochar, the product obtained by pyrolysis of biomass, is a new eco-friendly material with excellent properties and many promising applications. Among them it can be used as cathode in Zn-air batteries with very satisfactory results MethodsThe residue was obtained by anaerobic digestion of a mixture of corn silage (10%), malt (10%), and cattle manure (80%), aiming to biogas production. It was first freeze–dried and then it was subjected to pyrolysis up to 800oC. Significant findingsThe biochar was physicochemically characterized. It has moderate specific surface area, sufficient sp2/sp3 ratio and metal and non–metal surface chemical species. The biochar demonstrated satisfactory electrocatalytic performance, both as oxygen reduction and oxygen evolution catalyst. When applied as electrocatalyst in Zn–air batteries it reached an open–circuit potential of 1.45 V, a short–circuit current density of 200 mA cm–2 and maximum power density of around 62 mW cm–2. Its energy density was 927 Wh kg–1, (at 20 mA), and 518 Wh kg–1 (at 100 mA). In a charge–discharge mode at 10 mA, the potential varied between 1.35 and 1.90 V. These data, show that the waste biomass can be used as inexpensive material for Zn–air batteries and offers a useful approach to combine waste management with energy storage.

Respective Advantages of Growing Different Green Manure With Nitrogen Fertilization in Cotton‐Based Cropping Systems: Insights From a Three‐Year Field Study

ABSTRACTPlanting green manure to improve cash crop yield and soil health has been widely recognized, and understanding cash crop performance after green manure integration is pivotal for determining its potential to bolster and enhance crop productivity and sustainable production. However, it is unclear whether the effects of different types of green manure on subsequent cash crops are uniform. In order to clarify this issue, we systematically analyzed the effects of green manure types and nitrogen (N) application rates on succeeding cotton agronomic performance, yield, biomass, yield stability, and nutrient uptake. A split‐plot experiment with two factors was designed, main factor includes four cover cropping systems monoculture cotton (MC), February orchid/cotton cover cropping (FoC), hairy vetch/cotton cover cropping (HvC), and a mixture of February orchid and hairy vetch/cotton cover cropping (FHC), and sub‐main factor include four N application levels (0 (N0), 112.5 (N1), 168.75 (N2), and 225 (N3) kg N ha−1). Results suggests that nonlegume green manure (February orchid) accumulated more biomass, N, P, and K nutrients than the legume green manure (hairy vetch) and green manure mixture. Compared with cotton yield of MC, the FoC, HvC, and FHC system increased by 5.8%, 7.6%, and 15%, respectively. N use efficiency was more significantly influenced by the N application rates than by cropping systems. Specifically, as N application rates increased, N use efficiency decreased under MC, HvC, and FHC systems, while it increased under the FoC system. Additionally, we observed a trade‐off between cotton yield and yield stability, with the highest yield stability when cotton yield reached 2633 kg ha−1. This study provides evidence that nonlegume green manure (February orchid) with greater advantages on cotton vegetative organ growth, legume green manure (hairy vetch) can promote nutrient uptake compared to other green manure, while green manure mixture (February orchid and hairy vetch mixture) significantly increased cotton yield and yield stability. These findings provide evidence‐based insights highlighting the respective benefits of incorporating diverse species of green manure into cotton‐based cropping systems in the Yellow River Basin of China.

Tracing potentially toxic elements in button mushroom cultivation and environmental implications: Insights via stable lead (Pb) isotope analysis

Elevated levels of potentially toxic elements (PTEs) have been frequently detected in substrates used for cultivating edible mushrooms. However, the distribution and accumulation pathways of PTEs within mushrooms and their cultivation substrates remain inadequately understood. This study specifically aims to clarify these aspects of button mushrooms (Agaricus bisporus). A systematic analysis was conducted on the distribution of PTEs (As, Cd, Cr, Cu, Ni, Pb, and Zn) and stable Pb isotope fingerprints across various components of the button mushroom cultivation systems, including the cultivation substrates (a mixture of wheat straw, chicken manure, soil, and additives), fruiting bodies (MR), and spent mushroom substrate (SMS). The methodology involved inductively coupled plasma mass‒spectrometry for PTE quantification and Pb isotope ratio analysis for source identification. The results demonstrated that wheat straw and additives were the main contributors to the endogenous accumulation of PTEs in MR, accounting for 35.0% and 33.2% of Pb accumulation, respectively. Furthermore, MR, wheat straw, and soil together contributed to more than 67% of the Pb loads in SMS. The study also revealed that the occurrence of PTEs in these substrates is predominantly driven by exogenous sources, particularly the significant contribution from anthropogenic activities. Overall, these findings provide valuable biogeochemical insights into the accumulation pathways and patterns of PTEs in button mushroom cultivation systems, with potential applications for cleaner food management and environmentally sustainable practices.

Carbon‐to‐nitrogen stoichiometry of organic amendments regulates microbial biomass growth and nitrogen mineralization in soil

AbstractThe carbon‐to‐nitrogen (C:N) ratio of organic amendments regulates nutrient cycling in soil through its influence on microbial activity. Where an organic amendment has a C:N ratio sparingly higher than that of soil microbes (C:N ratio 6.7—8.7), meeting microbial requirements of carbon and nitrogen may promote microbial biomass growth and nitrogen mineralization. Here we sought to understand the microbial response to the addition of organic amendments with varying C:N ratios and subsequent changes in nitrogen mineralization and plant nitrogen uptake. Dried insect larvae, beef feedlot manure and mixtures of beef feedlot manure with insect larvae or sugarcane residue were used as soil amendments to create a gradient of molar C:N ratios (Cm:Nm) ranging from 6 to 28. An untreated control treatment with a C:N ratio of 17 was also included. Sorghum (Sorghum bicolor L.) was grown in control and organic matter amended soils for 20 days after germination. The mixture of beef feedlot manure and insect larvae treatment (Cm:Nm = 9.7) had on average 68% higher microbial biomass compared with the other treatments. Beef feedlot manure with Cm:Nm ratio of 11 did not influence microbial biomass growth. The concentration of mineral nitrogen was highest in the insect larvae (Cm:Nm = 6) treatment, where 23% of the plant nitrogen was derived from the insect larvae as indicated by the δ15N of plant dry matter. We observed both carbon and nitrogen contents in the organic amendment determine microbial biomass growth and nitrogen mineralization in soil. The results presented here demonstrate that microbial response to organic amendments determines the availability of mineral nitrogen in soil.

Organic fertilizer significantly mitigates N2O emissions while increase contributed of comammox Nitrospira in paddy soils

Nitrification is the dominant process for nitrous oxide (N2O) production under aerobic conditions, but the relative contribution of the autotrophic nitrifiers (the ammonia-oxidising archaea (AOA), the ammonia-oxidising bacteria (AOB) and the comammox) to this process is still unclear in some soil types. This is particularly the case in paddy soils under different fertilization regimes. We investigated active nitrifiers and their contribution to nitrification and N2O production in a range of unfertilized and fertilized paddy soils, using 13CO2-DNA based stable isotope probing (SIP) technique combined with a series of specific nitrification inhibitors, including acetylene (C2H2), 3, 4-dimethylpyrazole phosphate (DMPP) and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO). The soils had a long-term history of fertilizer application, including chemical fertilizer only, a mixture of chemical fertilizers (70 %) and chicken manure (30 %) or a mixture of rice straw and chemical fertilizers. 13CO2-DNA-SIP and Illumina MiSeq sequencing demonstrated that comammox clades A.1 and B were active nitrifiers in all fertilized paddy soils. Inhibitor experiment showed that AOB largely contributed to nitrification activity and N2O emission in all paddy soils, while comammox contribution was more significant than AOA. Fertilization considerably altered nitrifiers' relative contribution to nitrification activity and N2O emissions. Applying organic fertilizers significantly decreased the N2O emissions but increased the contribution of comammox to the process. These findings expand the functional ecological niche of comammox, revealing their nitrification role and N2O production in other ecosystems than oligotrophic habitats.

Green Manure Mediated Improvement in Saline Soils in China: A Meta-Analysis

The application of green manure is a traditional and valuable practice to improve the fertility of saline soil. However, the impact of environmental factors, green manure types and returning methods on the changes in soil fertility and soil salinity remain poorly quantified at a large scale. In the present study, we conducted a meta-analysis to generate a comprehensive evaluation of the effects of green manure on soil organic carbon (SOC), soil salt content, and soil nutrients compared to bare soil in China. The results showed that compared with bare soil, green manure planting could significantly increase the SOC content of saline soil, reduce salt content, and improve the soil total nitrogen (N), soil available phosphorus (P) and soil available potassium (K) contents. On average, green manure significantly enhanced SOC by 34.82% (percentage change), soil total N by 32.23%, soil available P by 34.34% and soil available K by 17.43%, while reducing soil salt content by 47.75%, compared to bare soil. In areas with a mean annual temperature (MAT) of <10 °C or a mean annual precipitation (MAP) of 200–400 mm, green manure had the largest increase in SOC, soil total N, soil available P, and soil available K. The smallest increases were observed in areas with an MAT above 15 °C and MAP greater than 800 mm. Green manure types influenced the improvement effect of green manure on saline soil. Green manure mixtures were more conducive to increases in SOC, while the increases in soil total N resulting from mixed green manure were lower in comparison to those from both legumes and non-legumes. In addition, the initial salt content, experimental years, and returning method influenced the improvement effect of green manure on saline soil. Therefore, this meta-analysis identified green manure as a promising practice for significantly improved saline soil in China.

EM4 Addition Effect with Eisenia foetida Worms on Compost Characteristics as a Soil Improver

A lot of fish waste is produced by the community, both from the marketing sector and the fisheries sector, which is caught by fishermen. Almost 35% of the fish waste produced is in the form of heads, bones, innards and also fish remains that are not the main catch which are thrown away directly. Vermicomposting is one of method to reduce the amount of fish waste. The adding of livestock manure in vermicomposting will increase the quality of compost. The purpose of this research is to analyze the compost quality with the mixture of fish waste and livestock manure. The results showed that The compost that has the best quality based on SNI 19-7030-2004 is B2 with 45% fish waste, 20% cow dung and 35% sawdust with a dose of EM4 10 ml, which has a final temperature of 29ºC, pH 7, water content 41%, C-organic 19.83%, nitrogen 1.34%, phosphorus 0.36%, potassium 1.15%, and C/N ratio 14.85. Then, after incubating the soil improvement, it was found that the addition of compost can improve the chemical characteristics of the soil according to the dose given. This indicates that compost application can affect soil quality. Soil quality that has C-organic and nitrogen content according to BPT in 2009 is with the addition of a dose of 5.2 grams of vermicompost. The shortcomings of this study are that the phosphorus and potassium levels are too high.

Study of synergistic behavior during bituminous coal-cow manure co-gasification: The role of intrinsic AAEM and organic matter

Co-thermal chemical conversion of coal and biomass is one of the important ways to realize efficient and clean utilization of coal. In this study, a typical Ningdong coal-Yangchangwan bituminous coal and cow manure were used to study the synergistic effect of intrinsic alkali, alkaline earth metals (AAEM) and organic matter on the co-gasification of coal and biomass by thermogravimetry analyzer (TG). The results showed that AAEM had obvious synergistic promotion effect on the gasification of a bituminous coal-cow manure mixture in the isothermal gasification (1000 ℃), whereas the organic matter will show the opposite effect on the process. To further investigate the effect of organic matter on the gasification process, the influence of organic matter on non-isothermal (25-1000 ℃) gasification reaction was investigated with heating rate of 10 ℃ /min, the kinetic parameters of the gasification reaction were obtained by Coats-Redfern method. The increase of biomass mass fraction in the sample facilitates the migration of alkali metals from the material to the solid phase. The possible mechanism of the synergistic effect of intrinsic AAEM/organic matter on the co-gasification process was proposed.

Optimizing Glutinous Corn Productivity through Demonstration Plots with the Application of Combined Organic Ameliorants

Sandy soil in Muncuk Karya, Ampenan, has low water retention and nutrient content, making it difficult for sticky rice farmers to meet their plants' water and nutrient needs. To overcome this challenge, research entitled "Optimizing Glutinous Corn Productivity through Demonstration Plots with the Application of Combined Organic Ameliorants" was carried out using an experimental methodology using a randomized block design involving five treatments and four replications, so that there were a total of 20 treatment plots. The treatments applied consisted of: A1 (50% cow manure + 50% mycorrhizal biofertilizer), A2 (50% compost + 50% mycorrhizal biofertilizer), A3 (50% fertile organic fertilizer + 50% mycorrhizal biofertilizer), A4 (50% rice husk charcoal + 50% mycorrhizal biofertilizer), and A5 (50% mixture of cow manure, compost, fertile organic fertilizer, and rice husk charcoal with a volume ratio of 1:1:1:1 + 50% mycorrhizal biofertilizer). The research results showed that the application of ameliorant, a combination of 50% cow manure and 50% mycorrhizal biofertilizer, was proven to be effective in increasing growth, plant productivity, soil nutrient concentration, plant nutrient uptake, and mycorrhizal development in the soil. To increase the productivity of sticky corn plants, soil fertility, plant nutrient uptake, and mycorrhiza development, it is recommended to use this combination ameliorant application.

Techno-economic optimization of agricultural biomass to electricity supply chain network: A case study of Tunisia

The manure biogas plant is a promising technology for the future. It represents a closed-loop system that reinforces the circular economy. However, effective and viable implementation requires optimization of the entire supply chain. In this paper, a cost optimization model for manure to electricity supply chain has been developed. The model aims to determine the best configuration for the biogas plant network (Decentralized/Centralized Biogas plant), identify the optimal locations and capacities, and give a distribution plan of materials flow within the supply chain while minimizing the overall costs. The novelty of this work consists in adopting a holistic approach that addresses a multi-region, multi-period and multi-product problem which considers seasonal variation in manure availability, different manure mixtures, the physico-chemical properties of manure and the technical aspects related to the biogas plant by adapting the open source tool OSEMOSYS. The model is applied to the Tunisian case study to provide the optimal pathway to achieve the Tunisian solar plan’s target of 100MW from biogas by 2030. As a result of the optimization, the optimal network of biogas plants across 6 regions in Tunisia is identified. Our results have shown that the LCOE of generating electricity across all regions ranges between 14.2 US$ cent/kWh and 19 US$ cent/kWh. Additionally, a sensitivity analysis on two key parameters distance and capital cost is performed.

Pengaruh Pemberian Kompos Campuran Ampas Tebu dan Kotoran Ayam terhadap Kesuburan Ultisol dan Hasil Produksi Kedelai (Glycine max (L.) merril)

Ultisol is a soil that contains low nutrients N, P and K and has the potential for Al-poisoning. Ultisol also has a low Cation Exchange Capacity, acidic soil pH and is sensitive to erosion. Improvements need to be made to increase Ultisol productivity, one of which is by adding organic ingredients. In addition to sugarcane bagasse compost, chicken manure contains many benefits because it contains a lot of organic materials that are good for the soil and plants. Increasing soybean yield is one of the priorities and can be done by utilizing Ultisol land. The purpose of this study is to determine the effect of composting a mixture of bagasse and chicken manure on ultisol fertility and soybean crop production. The research method carried out is experimental by conducting initial analysis of soil samples, compost application, maintenance, harvesting, soil analysis after compost application, calculation of height and crop yield. The results obtained were that the application of mixed compost of bagasse and chicken manure did not have a real effect on soil pH, P-available and Aldd, but could increase soil pH and P-available and lower Aldd in the soil. The application of mixed compost of bagasse and chicken manure was significantly different from plant height and was very different for soybean yield with the highest crop P3 (average plant height of 84.678 cm) and the highest yield of P3 3.938 tons/ha. The recommended treatment for soybean plants is P3 treatment with a dose of 15 tons/ha.

Effect of natural ageing on germination and seedling growth of Palmyrah (Borassus flabellifer) seeds

Experiments were conducted to evaluate the seed longevity period of Palmyrah. The matured fruit branches were selected based on yellow tinge in the stylar region. After manually removing the fruit exocarp and mesocarp, the uniform size seeds were shade dried for fourteen days and stored in ambient condition. The seeds were sown in raised nursery beds containing nursery mixture of red earth, sand and farmyard manure in a ratio of 2:1:1. The experiment was conducted in a randomized block design with three replications of 50 seeds each, sown at monthly intervals up to 18 months. The germination percentage was recorded at 15 days interval till the completion of germination. One year after sowing, the results revealed that fresh seed recorded highest germination of 78.67% followed by one month of stored seed (63.33%), two months of stored seed (53.33%) and nil germination was observed beyond five months of stored seed.

Effects of growing media, and cultivar on developments and quality of mango rootstock.

In a successful mango plant establishment, the choice of a strong and healthy rootstock is crucial for subsequent propagation. An experiment was conducted during the 2023 mango seedling growing season at the Sokoine University of Agriculture horticultural sections in Morogoro, Tanzania. The study aimed to evaluate the influence of different growing media and cultivars on the growth and development of quality-certified mango rootstock plants. Ripe local mango fruits were collected from neighbouring farms and sown in polyethylene bags containing a mixture of forest soil, sand, farmyard manure, and sawdust. The experiment followed a randomized complete block design with three replications. Data collected included days to 50% germination, seedling mortality, seedling height, stem girth, and chlorophyll content (measured using the SPAD Unit). Results indicated that using sindano cultivars as rootstock significantly reduced days to germination and increased germination percentage (89.5%) while minimizing seedling mortality (2). Additionally, forest soil contributed to maximum seedling height (43.95 cm), stem diameter (0.52 cm), and chlorophyll content (40.05). The interaction between cultivar and growing media significantly influenced various mango seedling growth parameters. Bongwa cultivars planted in growing media composed of forest soil alone or combined with farmyard manure and sand produced high-quality, certifiable mango rootstock plants.

Growth Response and Antibacterial Activity Test of Sintrong Plant (Crassocephalum crepidioides (Benth.) S. Moore) on different Growth Media and Shade

This study investigated the growth response and antibacterial activity of sintrong plants (Crassocephalum crepidioides (Benth.) S. Moore) on different growth media and shade to support organic functional food. The research was conducted at the Field Laboratory of the Faculty of Agriculture, Halu Oleo University using a two-factorial Randomized Group Design (RAK). Variations of planting media used were soil without fertilizer, a mixture of soil and cow manure in a ratio of 1:1, and a mixture of soil and cow manure in a ratio of 1:2. The variations of shade used were no shade, 25% paranet shade, and 50% paranet shade. Antibacterial activity was assessed using the Delusion method. Growth data and antibacterial activity were analyzed through Analysis of Variance (ANOVA) with SPSS application and continued with Duncan test at 95% confidence level (α = 0.05). The results showed that planting media and shade had a significant effect on the growth of sintrong plant height. The greatest growth occurred in a mixture of soil and manure 1:1 in 25% shade (P1N1), while the lowest growth occurred in a mixture of manure-soil 1:2 without shade (P2N0). Antibacterial activity testing showed a significant effect of various growing media and shade treatments. The highest antibacterial activity was found in sintrong plant extract grown without manure at 50% shade (P0N2), with an inhibition zone of 16.6 mm for Escherichia coli bacteria (gram negative) and 13.2 mm for Staphylococcus bacteria (gram positive). The lowest inhibition zone occurred in sintrong plants grown on 1:2 manure-soil mixture without shade (P2N0) with an inhibition zone of 8.0 mm for Staphylococcus aureus bacteria

Intermittent anaerobic-aerobic biopiling for remediating energetic compound-contaminated soils

Demolishing obsolete ammunition and live fire training, along with other military activities, contaminated military sites with energetic compounds (ECs), are raising human concerns. Biopiling is a green and sustainable technology for soil remediation due to its low cost and minimal secondary pollution. This study investigated the effects of various bio-stimulants in enhancing intermittent anaerobic-aerobic biopiling for ECs degradation in soil. The results showed that intermittent anaerobic-aerobic biopiling with municipal sludge, livestock and poultry manure, and agricultural and forestry wastes degraded 93.7 % 2,4,6-trinitrotoluene (TNT), 79.5 % hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and 92.0 % octahydro-1,3,5,7-tetranitro −1,3,5,7-tetrazocine (HMX) in 15 days. Correlation analysis of the energetic compounds showed that the TNT concentration and its reduction products changed conversely under anaerobic conditions, indicating a faster TNT reduction. Analysis based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database revealed an increase in the abundance of genes (nemA &porA) associated with nitrotoluene reduction. This study demonstrated that bio-stimulants composed of a mixture of municipal sludge, manure, and soil conditioner (SLA) could improve the physicochemical properties of the biopiling system and the microbial community structure, promoting the growth of Firmicutes that respond for the degradation of energetic compounds, including the influence of functional genes for TNT degradation.

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.

Moderate thermal post-treatment of digestate to improve biomethane production from agricultural- and food waste

The aim of this study was to assess the feasibility of moderate thermal treatment (70 °C for one hour) of digestate in combination with post-digestion targeting residual biomethane potentials from three full-scale biogas plants digesting food waste (FW), agricultural waste (AW) and a mixture of AW and manure (AWM). Dissolved organic carbon (DOC), biomethane production, and digestate quality were investigated. For the study six laboratory-scale continuously stirred tank biogas reactors working as post-digesters, with thermally-treated and non-treated digestate were used. DOC for thermally-treated digestates increased significantly (t-test, p < 0.05); FW-digestate (110–200 %), AW-digestate (24–92 %) and for AWM-digestate (4–73 %). Indexes for corresponding DOC quality showed lower apparent organic molecular weights and decreased aromaticity (with the exception of FW-digestate). Thermal treatment of digestate improved the biomethane production during post-digestion by 21–22 % (FW-digestate) and 9 % (AW-digestate). For AMW-digestate no clear positive effect was observed, most likely due to biogas plant operational process disturbances.

Complex hydrology and variability of nitrogen sources in a karst watershed.

Streams draining karst areas with rapid groundwater transit times may respond relatively quickly to nitrogen reduction strategies, but the complex hydrologic network of interconnected sinkholes and springs is challenging for determining the placement and effectiveness of management practices. This study aims to inform nitrogen reduction strategies in a representative agricultural karst setting of the Chesapeake Bay watershed (Fishing Creek watershed, Pennsylvania) with known elevated nitrate contamination and a previous documented groundwater residence time of less than a decade. During baseflow conditions, streamflow did not increase with drainage area. Headwaters and the main stem lost substantial flow to sinkholes until eventually discharging along large springs downstream. Seasonal hydrologic conditions shift the flow and nitrogen load spatially among losing and gaining stream sections. A compilation of nitrogen source inputs with the geochemistry and the pattern of enrichment of δ15N and δ18O suggest that the nitrogen in streams and springs during baseflow represents a mixture of manure, fertilizer, and wastewater sources with low potential for denitrification. The pH and calcite saturation index increased along generalized flow paths from headwaters to springs and indicate shorter groundwater residence times in baseflow during the spring versus summer. Given the substantial investment in management practices, fixed monitoring sites could incorporate synoptic water sampling to properly monitor long-term progress and help inform management actions in karst watersheds. Although karst watersheds have the potential to respond to nitrogen reduction strategies due to shorter groundwater residence times, high nitrogen inputs, effectiveness of conservation practices, and release of legacy nutrients within the karst cavities could confound progress of water quality goals.