On-farm Composting Research Articles

Evolution of microbiome composition, antibiotic resistance gene loads, and nitrification during the on-farm composting of the solid fraction of pig slurry using two bulking agents

Composting is a nature-based method used to stabilize organic matter and to transform nitrogen from animal farm manure or solid fraction of slurry (SFS). The use of composted material as source of nutrients for agriculture is limited by its potential to facilitate the propagation of biological hazards like pathogens and antibiotic-resistant bacteria and their associated antibiotic-resistance genes (ARG). We show here an experimental on-farm composting (one single batch) of pig SFS, performed under realistic conditions (under dry continental Mediterranean climate) for 280 days, and using two different bulking agents (maize straw and tree pruning residues) for the initial mixtures. The observed reduction in potentially pathogenic bacteria (80–90%) and of ARG loads (60–100%) appeared to be linked to variations in the microbiome composition occurring during the first 4 months of composting, and concurrent with the reduction of water-soluble ammonium and organic matter loads. Nitrification during the composting has also been observed for both composting piles. Similar patterns have been demonstrated at small scale and the present study stresses the fact that the removal can also occur at full scale. The results suggest that adequate composition of the starting material may accelerate the composting process and improve its global performance. While the results confirm the sanitization potential of composting, they also issue a warning to limit ARG loads in soils and in animal and human gut microbiomes, as the only way to limit their presence in foodstuffs and, therefore, to reduce consumers' exposure.

Agronomic, Economic and Environmental Comparative of Different Aeration Systems for On-Farm Composting

On-farm composting of agro-livestock wastes can be considered the most appropriate method for their recycling. Pile turning (PW) is one of the most widely used aeration systems for composting. However, this system has long composting periods and is inefficient at supplying oxygen and controlling the temperature. To minimize these drawbacks, the combination of turnings with forced aeration (PR) is an option; in this work, this combination was compared to PW as an aeration system for the co-composting of vegetable waste with different manures. In this comparative study, the evolution of the process, the compost quality and the economic and environmental impacts of the process were evaluated. The PR system was more appropriate for obtaining sanitized composts (the temperature was ≥55 °C for at least three consecutive days) with an adequate degree of maturity. Furthermore, this system reduced the organic matter and nutrient losses, yielding composts with higher agronomic value and a higher total combined value of the nutrients than those obtained using the PW system. However, the energy consumption and associated CO2 emissions were lower for the PW system, since this aeration system was based only on turnings without the use of forced aeration, as in the case of the PR system. Agricultural valorization of composts will offset this energy consumption and its impact, since it will contribute to reducing the use of synthetic fertilizers. However, more studies are required on the PR composting system and other agro-livestock wastes for the creation of centralized on-farm composting sites, where all steps of the composting chain are optimized.

Composting of Municipal Solid Waste Using Earthworms and Ligno-Cellulolytic Microbial Consortia for Reclamation of the Degraded Sodic Soils and Harnessing Their Productivity Potential

The management of municipal solid waste (MSW) and the reclamation of degraded sodic soils are two serious environmental and socio-economic problems experienced by the developing nations. To overcome these problems, a technology has been developed for the composting of MSW using earthworm and ligno-cellulolytic microbial consortia and its utilization for the sustainable reclamation of degraded sodic soils, as well as for harnessing their productivity potential. To standardize on-farm composting under aerobic conditions, the field experiment consisted of seven treatment combinations, replicated thrice with municipal solid waste (MSW) sole and in combination with agricultural wastes (AW) treated with earthworms (Eisenia foetida) and consortia of lingo-cellulolytic microbes such as Aspergillus spp., Trichoderma spp. and Bacillus spp. It was conducted at ICAR-CSSRI, Research farm, Shivri, Lucknow, India. The results revealed that the thermophilic phase was achieved at 60 days of composting and thereafter the temperature decreased. Marked changes in pH and EC were found and they changed from acidic to neutral. The reduction in total C, from initial to maturity, varied from 4.45 to 14.14% and the increase in total P and total K from 4.88 to 88.10% and 12.00 to 35.71%, respectively. The nutrient-rich quality compost based on the lowest C: N ratio, highest nutrient contents, microbial population (bacteria and fungi) and enzymatic activities was obtained from a mix of MSW and AW, enriched with earthworms and consortia of lingo-cellulolytic microbes. The efficacy of this enriched compost was evaluated for the reclamation of sodic soils and their potential for sustaining productivity of the rice-wheat cropping system was harnessed through combined application with a reduced dose of gypsum. The results indicated that the application of on-farm compost @10 t ha−1 in conjunction with a reduced quantity of gypsum (25% GR) significantly (p < 0.05) improved the physico-chemical and microbial soil properties, and enhanced productivity of the rice-wheat cropping system over the use of only gypsum. This study proved that on-farm compost of MSW and its utilization for the reclamation of degraded sodic soils can be an alternate solution for useful disposal and management of MSW, thereby improving the health and productivity of sodic soils.

On-Farm Composting of Agricultural Waste Materials for Sustainable Agriculture in Pakistan.

Agriculture is the economic backbone of Pakistan. 67% of country's population resides in rural areas and primarily depends on agriculture. Pakistan's soils are poor in OM and have a low C : N ratio, and the overall fertility status is insufficient to support increased crop yields. Compost is an excellent alternative solution for improving soil OM content. However, this excellent alternative supply in Pakistan has yet to be used. Mass volumes of leaves, grass clippings, plant stalks, vines, weeds, twigs, and branches are burned daily. In this study, different compost piles (P1, P2, and P3) of compost were made using different agricultural and animal waste combinations to assess temperature, pH, and NPK. Results revealed that P3 demonstrated the most successful composting procedure. The temperature and pH levels throughout the composting process were determined in a specified range of 42–45oC and 6.1–8.3, respectively. Total nitrogen content ranged from 81.5 to 2175 ppm in farm compost. Total phosphorus concentrations range from 1.33 to 13.98 ppm, and potassium levels, on the other hand, range from 91.53 to 640 ppm in farm compost. The overall nitrogen concentration grew progressively between each pile at the end of a week. The varied concentrations revealed that adding various forms of agricultural waste would result in a variation in the quantity of NPK owing to microbial activity. On-farm composting has emerged as an effective technique for the sustainability of agricultural activities, capable of resolving crucial problems like crop residues and livestock waste disposal. Based on this study's results, the pile (P3) combination shows the best NPK value performance and is recommended for agricultural uses to overcome the OM deficiency.

On-Farm Composting of Hop Plant Green Waste—Chemical and Biological Value of Compost

Green agro waste can be turned into compost, which can then be used as an organic fertilizer, thus reducing the environmental impact of food and feed production. This research is focused on finding a feasible on-farm composting treatment of plant biomass to produce high-quality compost. Three different composting treatments were prepared and followed (with different additives at the start—biochar (BC) and effective microorganisms (EM), no additive (CON); covering and not covering the pile; different start particles size). Samples were analysed for nutrient concentrations, phytotoxicity and bacterial and fungal presence after seven months of composting. In 100 g of dry matter, the average compost contained 2.7 g, 0.38 g and 1.08 g of N, P and K, respectively. All investigated treatments contained more than 2% of total nitrogen in dry mass, so they could be used as a fertilizer. The highest nutrient content was observed in compost of small particle size (˂5 cm) and added biochar (11 kg/t fresh biomass). However, this compost had the least bacteria and fungi due to very high temperatures in the thermophilic phase of this pile. According to the radish germination index, the prepared composts have no phytotoxic properties and are stable and ready to use in plant production. Taking the cress germination test into consideration, they provided a nutrient-rich and biostimulative soil amendment. All three final composts were stable in terms of respiration rate, growth and germination tests. Results have shown that hop biomass after harvest has great potential for composting.

Agronomic and Environmental Performances of On-Farm Compost Production and Application in an Organic Vegetable Rotation

Horticultural crops produce huge amounts of wastes due to the large difference between total and marketable yields, and plant residues. The biological stabilization and sanitization of these organic materials directly on-farm through a simple technique such as composting may be a feasible and sustainable management strategy. The objectives of this research were to (i) estimate the sustainability and the energy impact of the on-farm composting process; (ii) to evaluate the agronomic performance and sustainability of the compost application, compared to a commercial organic fertilizer; and (iii) to identify the management and environmental hotspots. To accomplish these aims, a composting process was set up and monitored using the organic wastes and residues produced in the experimental farm. The compost produced was compared to a commercial organic fertilizer in combination with the use of cover crops in the rotation, in a two-year pepper cultivation. All processes were assessed using an energy analysis and a carbon stocks and emissions evaluation. Our findings point out that the composting process on-farm was environmentally sustainable in terms of energy consumption and carbon emissions and produced a good quality fertilizer. The use of this compost determined the best agronomic performance, especially when it was combined with other agro-ecological techniques. The yield values were slightly higher and statistically comparable with the commercial fertilizer ones. Moreover, the treatments that included the compost were most energy efficient and showed the best compromise between C emissions and C stocks.

Evaluation of Compost from On-Farm Composting of Coffee Pulp Using Wood Chips and Air Flow

Being the second largest coffee producing country worldwide, Vietnam is estimated to annually generate approximately 1 million m3 of coffee pulp. Instead of being effectively utilized in the form of recycling resources, most of the waste is discarded, causing serious environmental pollution even though it contains essential macronutrients in high concentrations. In this study, we performed on-farm composting trials of coffee pulp with simple aeration using wood chips and air flow. After 2 months of composting, samples were collected for analysis and a cultivation experiment was conducted to clarify the effectiveness of the composts. Coffee pulp compost was a nutrient-rich organic material with the total C, total N and total K in the range of 340.35–386.02 g kg–1, 23.80–36.70 g kg –1, and 18.86–25.13 g kg–1, respectively. The C:N ratio was in the range of 10–15 and the NH4–N:NO3–N ratio was in the range of 1–2, indicating compost was mature. In the compost where wood chips were used as the bulking agent under air flow, exhibited a concentration of inorganic N that was significantly higher than that of the other composts. The plant biomass corresponding to the compost showed similarity with chemical fertilizer. Furthermore, the P content and the plant biomass produced by the compost in which chicken manure was added, were investigated. The results indicate that the addition of P-source in the manufacturing process enhanced the fertilizing efficiency of the compost.

Microbiota Characterization of Agricultural Green Waste-Based Suppressive Composts Using Omics and Classic Approaches

While the control of soil-borne phytopathogenic fungi becomes increasingly difficult without using chemicals, concern over the intensive use of pesticides in agriculture is driving more environmentally sound crop protection managements. Among these approaches, the use of compost to suppress fungal diseases could have great potential. In this study, a multidisciplinary approach has been applied to characterize microbiota composition of two on-farm composts and assess their suppress and biostimulant activities. The on-farm composting system used in this study was able to produce two composts characterized by an antagonistic microbiota community able to suppress plant pathogens and biostimulate plant growth. Our results suggest a potential role for Nocardiopsis and Pseudomonas genera in suppression, while Flavobacterium and Streptomyces genera seem to be potentially involved in plant biostimulation. In conclusion, this study combines different techniques to characterize composts, giving a unique overview on the microbial communities and their role in suppressiveness, helping to unravel their complexity.

Composting of municipal solid waste and farm wastes for its use as amendment in sodic soil

A study was conducted to utilize municipal solid waste and farm wastes in different combinations for composting with and without use of earthworms and lingo-celluloytic microbes. A total of seven combination treatments were set up for on-farm composting. The compost generated at maturity from different treatments was analyzed for physico-chemical properties and nutrient content to promote its use as soil amendment to improve fertility and productivity of sodic soil. The composting process was completed in all treatment at 120 days. During composting, temperature under different treatments varied between 24 to 27°C and moisture content ranged between 43.88 to 69.32%. At maturity, the pH and EC of the matured compost increased slightly from 6.97 to 7.48 as compared to initial values of composting material. Total nitrogen, total phosphorus, total potassium and calcium contents also increased at the maturity of the compost. The prepared compost applied to sodic soil under rice-wheat cropping system indicated its ameliorative potential. The soil pH reduced from 9.8 to 8.8 and ESP reduced from 78.3 to 28.0 and there was build up organic C and nutrients. Bulk density and infiltration characteristics of soil also improved.

On-farm compost: a useful tool to improve soil quality under intensive farming systems

Conventional agriculture that uses extensive tillage without organic inputs to soils can cause a degradation in soil quality. The improvement of soil organic matter (SOM) content can be achieved through the use of organic amendments. Application of organic amendments, such as compost, is a reliable tool to improve soil quality. On-farm composting is an ecological technology and can be used to recycle agricultural waste materials, such as animal manure or crop residues, that can be incorporated into the soil to improve soil quality. Therefore, the objective of this work was to characterize, by CPMAS-NMR spectroscopy and chemical properties, a commercial organic waste compost and an on-farm compost and, then, to compare their use as organic amendments on soil quality. A greenhouse study on intensive agricultural soils of Southern Italy was done. The following amendments, as soil treatment, were used: a municipal compost (MC), with C:N 13.3, and an on-farm compost (OF), with C:N 17.1, applied at the rate of 8.5 and 6.0 Mg DMha−1, respectively. After one, four, eight, twelve and fifteen months soil samples were collected and analyzed for chemical (pH, electrical conductivity, limestone, CEC, available phosphorus, organic carbon, total nitrogen and exchangeable bases) and microbial (urease, phosphomonoesterase, β-glucosidase, total hydrolytic activity and Biolog Ecoplate™) properties. MC compost was characterized by larger electrical conductivity and exchangeable Na+ content with respect to OF compost, while this latter was characterized by about twice of organic carbon (470gkg−1). As showed by CPMAS-NMR spectroscopy, OF compost was characterized not only by cellulosic polysaccharides, but also significant amounts of both alkyl components and lignin derivatives. An effective increase of soil organic carbon (SOC) in plots under MC (+36%) and OF (+25%) composts, respectively, was reached at the end of the experiment. Soil amendments improved soil biological functions as revealed by a general trend of positive effects on hydrolase activity, phosphomonoesterase, β-glucosidase as well as urease. EC and exchangeable Na+ were considerably larger only in the plots under MC compost (25% and 19%, respectively), with respect to control plot. The possible increase of soil salinity after compost amendment may negatively affect soil quality in the long-term. In conclusion, our results demonstrated that the supply of compost produced on-farm, can enhance soil biological and biochemical properties, without the drawbacks of municipal composts, representing a promising alternative to the latter and an important way to reuse wastes produced by cultivation and processing of vegetables.

Opportunities and barriers to on-farm composting and compost application: A case study from northwestern Europe

Maintaining and increasing soil quality and fertility in a sustainable way is an important challenge for modern agriculture. The burgeoning bioeconomy is likely to put further pressure on soil resources unless they are managed carefully. Compost has the potential to be an effective soil improver because of its multiple beneficial effects on soil quality. Additionally, it fits within the bioeconomy vision because it can valorize biomass from prior biomass processing or valorize biomass unsuitable for other processes. However, compost is rarely used in intensive agriculture, especially in regions with high manure surpluses. The aim of this research is to identify the barriers to on-farm composting and the application of compost in agriculture, using a mixed method approach for the case of Flanders. The significance of the 28 identified barriers is analyzed and they are categorized as market and financial, policy and institutional, scientific and technological and informational and behavioral barriers. More specifically, the shortage of woody biomass, strict regulation, considerable financial and time investment, and lack of experience and knowledge are hindering on-farm composting. The complex regulation, manure surplus, variable availability and transport of compost, and variable compost quality and composition are barriers to apply compost. In conclusion, five recommendations are suggested that could alleviate certain hindering factors and thus increase attractiveness of compost use in agriculture.

Agricultural waste-based composts exhibiting suppressivity to diseases caused by the phytopathogenic soil-borne fungi Rhizoctonia solani and Sclerotinia minor

On-farm composting is an efficient, environmentally safe and cost-effective process for recycle vegetable residues into productive cycles. Benefits of these composts could include their ability to mediate soil-borne plant pathogen suppression with a significant impact on eco-friendly crop management. In this work, on-farm composts were assayed for ability to control, both in vitro and in vivo, damping-off causing pathogens Rhizoctonia solani and Sclerotinia minor. Tomato and escarole-derived compost was the most suppressive and, furthermore, together with that derived from artichoke wastes, exhibited multi-suppressive activity. Compost communities, characterized at metabolic and global levels by Biolog system, microbial counting, CO2-release and FDA hydrolysis rate, play a major role in compost-based biological control. The complete biotic inactivation by autoclaving composts, has, in fact, reduced or eliminated their ability in pathogen suppression. Solid state 13C CPMAS-NMR spectroscopy revealed that spectral areas typical for phenolic C, as well as methoxyl C, may be associated to suppressivity mechanism(s). These evidences suggested that the ecological relationships between organic carbon molecular distribution and microbial structure may contribute to discriminate suppressive composts from null and conducive ones. Nutritional microniches in compost may then have profound effects on the community functions, including those linked to the suppressiveness.

Simple technologies for on-farm composting of cattle slurry solid fraction

Composting technologies and control systems have reached an advanced stage of development, but these are too complex and expensive for most agricultural practitioners for treating livestock slurries. The development of simple, but robust and cost-effective techniques for composting animal slurries is therefore required to realise the potential benefits of waste sanitation and soil improvement associated with composted livestock manures. Cattle slurry solid fraction (SF) was collected at the rates of 4m3h−1 and 1m3h−1 and composted in tall (1.7m) and short (1.2m) static piles, to evaluate the physicochemical characteristics and nutrient dynamics of SF during composting without addition of bulking agent materials, and without turning or water addition. Highest maximum temperatures (62–64°C) were measured in tall piles compared to short piles (52°C). However, maximum rates of organic matter (OM) destruction were observed at mesophilic temperature ranges in short piles, compared to tall piles, whereas thermophilic temperatures in tall piles maximised sanitation and enhanced moisture reduction. Final OM losses were within the range of 520–660gkg−1 dry solids and the net loss of OM significantly (P<0.001) increased nutrient concentrations during the composting period. An advanced degree of stabilization of the SF was indicated by low final pile temperatures and C/N ratio, low concentrations of NH4+ and increased concentrations of NO3- in SF composts. The results indicated that minimum intervention composting of SF in static piles over 168days can produce agronomically effective organic soil amendments containing significant amounts of OM (772–856gkg−1) and plant nutrients. The implications of a minimal intervention management approach to composting SF on compost pathogen reduction are discussed and possible measures to improve sanitation are suggested.

Low-input, on-farm composting of high C:N ratio residues

AbstractFarm residues with high C:N ratios are difficult to use because of their low economic value and excessive volume. Composting is ideal for upgrading such residues, but was not thought possible without co-composting or lowering of the C:N ratio. We developed a low-input method to compost perennial ryegrass straw on-farm by forming windrows and turning them either zero, two, four, or six times throughout the year with a commercial, straddle-type turner. No water beyond normal rainfall and no N other than that contained in the straw was added. The volume of straw was reduced by up to 88% with four or six turns over 20 to 24 weeks. The average internal temperature of straw windrows reached a maximum of 54°C with four turns. The ability to compost these residues will help in the development of sustainable farming systems by allowing recycling of straw waste.