The valorization of livestock and agri-food waste has become a key element So that Spanish agriculture can continue producing reliably amidst the current crisis of raw materials, fertilizers, and energy. What was once seen as a nuisance—slurry, manure, chicken manure, sludge, or byproducts of the agri-food industry—is now considered a strategic raw material for generating circular fertilizers, biogas, biodegradable materials, and solutions to improve soil health.
In recent years, very powerful projects, regulations, and technologies have emerged. which demonstrate that, if managed well, agricultural and livestock waste not only ceases to be an environmental risk, but also helps to close the nutrient cycle, reduce dependence on imported synthetic fertilizers, produce renewable energy and move towards a real circular economy model in rural areas.
Valorization of livestock waste within the circular economy
When we talk about the valorization of livestock waste, we are referring to transforming by-products such as manure, slurry, chicken manure and organic waste. in useful resources: organic or circular fertilizers, soil amendments, bioenergy, compounds of industrial value, or agricultural biocides. The goal is not just to "get rid of" the waste, but to reintegrate it into the production system safely and profitably.
The circular economy applied to the agricultural and livestock sector aims to ensure that nutrients never leave the systemThe nitrogen, phosphorus, and potassium found in livestock manure and agricultural byproducts are recovered and returned to the agricultural soil as fertilizers or organic amendments. This reduces the need to import mineral fertilizers, lowers costs, and protects the environment.
This approach is fully aligned with European prioritiesespecially with the European Union's so-called "Soil Mission", which focuses on restoring soil health by 2030. The valorization of agricultural, livestock and forestry waste is one of the most effective levers to improve organic matter, promote microbial activity and increase the soil's capacity to store carbon.
Furthermore, the supply crisis and the rising cost of nitrogen fertilizersThese challenges, exacerbated by geopolitical situations such as the blockade of the Strait of Hormuz, have highlighted the vulnerability of the current agricultural model, which is highly dependent on external inputs and fossil fuels. Recovering nutrients from livestock waste is no longer just an environmentally sound option: it is a strategic necessity.
The AGROVALOR project and the comprehensive revaluation of agricultural and livestock waste
One of the most complete examples of this paradigm shift is the AGROVALOR project, an initiative that seeks to give a second life to agri-food and livestock waste and by-products through advanced technologies and innovative applications in different productive sectors.
Under the coordination of Itagra.ct and with the participation of the Miranda de Ebro Technology Centre (CTME), Cesefor and CETECEAGROVALOR focuses on transforming agricultural, livestock, industrial and forestry waste into high value-added resources, with uses ranging from human and animal food to agriculture, biotechnology or the manufacture of sustainable materials.
Among the project's technical objectives, several very specific areas stand out.: developing food supplements from by-products, obtaining active compounds of industrial interest, producing additives capable of giving new properties to bioplastics, designing agricultural biocides of organic origin and optimizing biotechnological processes to improve the cultivation and processing of microorganisms.
CTME, in particular, is committed to creating biodegradable materials that incorporate agricultural by-products into their formulation.as well as by researching new applications that facilitate the reuse of waste in industry. In this way, the center reinforces its commitment to sustainability, technological innovation and support for the agri-food industry of Castilla y Leongenerating positive impacts on both the regional economy and the environment.
The project is co-financed by the Institute for Business Competitiveness of Castilla y León (ICECyL) and the European Regional Development Fund (ERDF), within the framework of the ERDF Operational Programme 2021-2027. It falls within the specific objective of developing and improving research and innovation capabilities and the priority of digital and smart transition, contributing to a more competitive, innovative and connected Europe.
The AGROVALOR Conference: Science, Business and Administration Regarding Waste
Alongside technological development, AGROVALOR has also promoted a space for knowledge exchange. with the celebration of the 1st AGROVALOR Conference: “Valorization of agricultural, livestock and forestry waste for soil health and the circular economy”, whose book of abstracts includes 57 pages of technical contributions and real cases.
This conference, held in Seville on May 20 and 21, 2025The event brought together 49 participants from eleven private companies, three public entities, five universities, and six research centers. This created a highly active forum where academia, the business sector, and government could discuss and seek joint solutions to advance towards a more circular and competitive agriculture.
The program was structured into five thematic blocks that covered the entire valorization cycle.The first one revolved around the transformation of biomass through pyrolysis, presenting innovative experiences in the generation of biochar, renewable energy and new products from agricultural and forestry waste.
The second block focused on circular agriculture and the integration of waste into farming systemsThe conference addressed both business approaches and solutions developed within academia. Special emphasis was placed on how organic waste can be reintegrated into the agricultural system without compromising environmental quality and, at the same time, improving soil fertility.
The third session dealt with resilient agriculture and climate changeThe first session showcased adaptive farming practices, carbon sequestration strategies, and ways to reduce the climate footprint through organic amendments such as compost, biochar, and digestate. The fourth session directly analyzed the link between soil health and productivity, presenting five studies that demonstrated the positive impact of these amendments on soil physical and chemical properties, microbial activity, and crop yields.
Finally, the fifth block addressed environmental applications beyond fertilizationThe day included the filtration and adsorption of contaminants, remediation of degraded soils, and water treatment using recycled and transformed organic materials. The day also featured technical visits to key facilities in the region, such as the EMASESA El Copero Environmental Complex, test plots with engineered soils, the Montemarta Cónica CIT (Technological Innovation Center), and the IRNAS-CSIC “La Hampa” Experimental Farm, where the discussed solutions could be observed in the field.
Nutrient recovery: circular fertilizers from livestock waste
One of the hottest debates related to the valorization of livestock waste has to do with nutrient recovery, especially nitrogen, to reduce dependence on synthetic fertilizers. In the current context of supply crises, this issue has taken on enormous importance.
The Spanish Veterinary Association (OCV) has insisted that Spain could recover between 200.000 and 400.000 tons of nitrogen annually. If livestock by-products, mainly slurry, sludge, and other animal waste, were properly utilized, these figures represent a significant leap forward in the productive autonomy of one of the EU's leading livestock-producing countries.
To achieve this, the OCV proposes to promote nitrogen recovery technologies, such as the well-known RENURE solutions, which transform slurry and other livestock effluents into high-performance circular fertilizers. Simultaneously, this waste can be used to produce biogas, generating renewable energy and reducing emissions associated with fossil fuels.
The Federation of European Veterinarians has already warned that reducing dependence on synthetic fertilizers linked to fossil fuels is a priority.focusing on the biological nitrogen present in manure and animal by-products. This vision aligns with a circular bioeconomy model in which waste is reintegrated into the production cycle as a valuable resource, and extensive livestock farming plays a fundamental role as a source of organic fertilizer for crops.
In addition to improving fertilizer autonomy, nutrient recovery helps restore degraded soilsToday, nearly 60% of the soils in the European Union show signs of degradation, compromising both agricultural productivity and carbon sequestration capacity. The planned application of manure, compost, digestate, or biochar is one of the most effective strategies to reverse this situation.
Regulatory framework and operation R1001: conditions for safe valuation
For the agricultural valorization of organic waste to be a real tool and not a source of problemsIt is essential to comply with a set of legal and technical requirements. In Spain, the R1001 operation for the valorization of agricultural and garden land establishes the framework for this practice to be carried out with guarantees.
Operation R1001 is based on incorporating organic waste into the soil for a clear agronomic purposeTo provide nutrients to crops and increase soil organic matter, while properly managing waste. This requires compliance with Law 7/2022 on waste and contaminated soils for a circular economy, as well as Royal Decree 1051/2022 on sustainable nutrition of agricultural soils.
This Royal Decree establishes technical criteria for the application of waste and by-products in the fieldIt addresses dosage limits, quality requirements, traceability, application frequencies, analytical controls, and compatibility with fertilization plans. It also emphasizes the obligation to prevent impacts on surface and groundwater, especially in areas vulnerable to nitrate pollution.
The autonomous communities complement this state legislation through specific action programs In nitrate-vulnerable areas, such as Order MAV/398/2022 in Castile and León, which regulates the management of nitrogen from agricultural and livestock sources in these areas. Other relevant frameworks include the Draft of Regional Biomethanization Plan in Castilla-La Mancha or the Catalan Digest Strategy and its 2024-2030 action plan.
This entire regulatory framework makes it necessary to plan the valuation very carefully.Authorities require technical reports and management plans that justify the suitability of the waste, its quality, the applicable doses, and its compatibility with the soil and crop characteristics. Companies specializing in environmental management prepare these studies, combining laboratory analyses, agronomic studies, nutrient balances, and GIS mapping.
Types of livestock waste with the greatest potential for valorization
Livestock farms generate large volumes of organic wasteThese products have a high potential for pollution if mismanaged, but also significant agronomic and energy value if properly treated. The main farm wastes are organic and biodegradable.
Among the most common waste products are solid manure, slurry, and chicken manure.Manure mixes animal excrement with bedding materials such as straw, sawdust, or plant debris, forming an organic fertilizer rich in volatile fatty acids, proteins, polysaccharides, and lipids. Slurry combines liquid and solid livestock waste with leftover feed and wash water.
The chicken manure comes from poultry farms. It is composed mainly of bird droppings and bedding material. Due to the birds' low digestive efficiency, it can contain up to 81% of the nitrogen, 88% of the phosphorus, and 95% of the potassium ingested, making it a highly concentrated source of nutrients, but also a material that must be handled with care.
Quantitatively, it is usually estimated that the daily amount of manure and slurry generated It represents approximately 7% of the animals' live weight. This gives an idea of the enormous volume that pig farms, cattle farms, or other intensive farming operations can generate, and the importance of having robust management systems.
If these wastes are not treated properly, the environmental impacts are numerous.These include emissions of harmful gases and foul odors into the atmosphere, salinity problems or the accumulation of heavy metals in soils, high organic loads in surface waters, nitrate leaching into aquifers, eutrophication of water bodies, and the presence of pathogens. Therefore, prevention and good management practices are the first line of defense.
Environmental and health risks of poor management
Untreated or improperly applied slurry, manure, and poultry litter quickly become a problem. for the environment and for the farm itself. In the air, they can release gases such as ammonia and hydrogen sulfide, which not only generate bad odors, but also pose risks to the health of workers and animals.
In the soil, excessive or indiscriminate application of these residues can alter the pH.It can excessively increase salinity, promote the accumulation of heavy metals, and have detrimental effects on certain crops. Furthermore, it can increase the presence of pathogens and cause imbalances in the soil's microbial community.
In the water, the most serious problem is the leaching of nitrates and nitrites into aquifers and surface watercourses, contributing to eutrophication processes and posing a risk to both drinking water quality and aquatic ecosystems. The presence of fecal matter and pathogenic microorganisms adds a health component that should not be underestimated.
Therefore, the best strategy is to act from a preventative standpoint.: reduce waste generation as much as possible, improve the design of facilities to minimize washing water, optimize livestock feeding and apply appropriate treatments to effluents, so that they can be used for productive purposes without generating unacceptable impacts.
In this context, extensive livestock farming has an interesting role as a system more integrated with the territory.where some fertilization can be done directly on pastures and crops. However, even in these cases, technical advice and monitoring are necessary to avoid nutrient overload in certain areas.
Treatment technologies: physical, biological and energy recovery
To transform livestock waste into usable resources, a combination of physical and biological treatments is used., which allow the stabilization of organic matter, reduce its polluting potential and adapt its characteristics to the desired end use.
Physical treatments include operations such as sieving or screening to remove coarse elementsThe process involves mixing to homogenize the waste and mechanically separating it into solid and liquid fractions using presses or sieves of different types. The solid fraction is usually used for stabilization and composting processes, while the liquid fraction is decantated to remove sludge.
The sludge obtained by sedimentation can be incorporated back into the solid fraction for co-fermentationOptimizing the overall management of the waste. There are also physical technologies such as dehydration or incineration, although these usually involve higher investments and, in many cases, less value added to the final product, so they are used in specific situations.
Regarding biological treatments, aerobic digestion is the basis of composting.In the presence of oxygen, communities of bacteria and fungi degrade organic matter, generating carbon dioxide and transforming the initial mixture into a stabilized compost, which is safer, has fewer pathogens and odors, and possesses very interesting agronomic properties as a soil amendment.
On the other hand, anaerobic digestion takes place in the absence of oxygen, usually in biodigestersIn this process, specialized microbial consortia break down organic matter to produce biogas—composed mainly of methane and carbon dioxide—and a digestate that retains much of its fertilizer value. The process is often enhanced by adding specific bacteria, enzymes, or yeasts.
The biogas generated can be used for the production of electrical and thermal energyThis contributes to reducing the farm's carbon footprint and improving its energy balance. Furthermore, if it is purified to a certain quality... biomethaneIt can be injected into the grid or used as a renewable fuel in mobility or industrial processes.
Anaerobic digestion is particularly well positioned as a tool for reducing greenhouse gas emissions.This prevents the uncontrolled release of methane from the natural decomposition of waste and channels it towards a useful energy source. At the same time, it allows most of the nutrients to be preserved in the digestate, which can then be used for agricultural purposes.
Agricultural valuation: technical reports, management plans and digestate
To safely apply organic waste and by-products in the field, the authorities require detailed technical reports. that plan the entire management of agricultural valorization: from the characterization of the residue to the doses per hectare and its integration into fertilization plans.
These reports usually include the identification of the waste and the receiving plots, the collection of samples and their analysis in accredited laboratories, agronomic studies of soils and crops, macronutrient balances such as nitrogen, phosphorus and potassium, and the development of thematic maps using geographic information systems to delimit application areas.
In addition, a technical report is prepared that describes the application operations and justifies their compliance with the regulationsThis includes assistance with the necessary administrative procedures to obtain permits or report activities. Specialized environmental companies offer these services to producers of agri-food waste, as well as to owners of agricultural holdings or managers of non-hazardous waste.
The case of digestate from biogas and biomethane plants deserves specific mention.This byproduct of anaerobic digestion can have significant agronomic value, but its use is highly regulated. Many autonomous communities require the development of digestate management plans that specify its characteristics, storage and application systems, target crops, and maximum doses per hectare.
In regions such as Catalonia or Castilla-La Mancha, specific strategies have already been designed. To promote the safe use of digestate and facilitate its integration into regional biomethanization plans, always under the umbrella of state regulations on waste and sustainable soil nutrition. This rigorous planning is key to making digestate a solution and not a new problem.
In parallel, the implementation of collective biogas plantsThese facilities combine waste from several farms and, in many cases, co-digestion with other organic waste from agro-industrial sources. This integrated management model, organized by geographic area, allows for cost sharing, facility optimization, and the generation of environmental, economic, and social benefits for the region.
Ultimately, it's about combining good technologies, regulatory compliance, and planning.Livestock waste is going from being a headache to becoming a tool for producing circular fertilizers, generating renewable energy, improving soil health and strengthening the resilience of the agri-food system to supply crises and the demands of climate change.