The valorization of livestock and agri-food waste has become a key element for Spanish agriculture to 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, powerful projects, regulations, and technologies have emerged that demonstrate that, if managed properly, 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 byproducts such as manure, slurry, poultry litter, and organic remains into useful resources: organic or circular fertilizers, soil amendments, bioenergy, compounds of industrial value, or agricultural biocides. The goal is not simply to get rid of the waste, but to reintegrate it safely and profitably into the production system.
The circular economy applied to the agricultural sector aims to ensure that nutrients never leave the system : nitrogen, phosphorus, and potassium found in livestock manure and agri-food 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 priorities , especially 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 for improving organic matter, promoting microbial activity, and increasing the soil's capacity to store carbon.
Furthermore, the supply crisis and the rising cost of nitrogen fertilizers , 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 Technological Center of Miranda de Ebro (CTME), Cesefor and CETECE , AGROVALOR 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 technical objectives of the project, several very specific fronts 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 byproducts into their formulation , as well as 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 Castile and León , generating 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 event, held in Seville on May 20 and 21, 2025 , brought together 49 participants from eleven private companies, three public entities, five universities, and six research centers. It 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 covering the entire valorization cycle . The first focused on biomass transformation through pyrolysis, presenting innovative experiences in the generation of biochar, renewable energy, and new products from agricultural and forestry waste.
The second section focused on circular agriculture and the integration of waste into farming systems , addressing both business approaches and solutions developed within academia. Particular 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 focused on resilient agriculture and climate change , showcasing adaptive farming practices, carbon sequestration strategies, and ways to reduce the climate footprint using 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 session addressed environmental applications beyond fertilization : filtration and adsorption of pollutants, remediation of degraded soils, and water treatment using recycled and transformed organic materials. The day concluded with technical visits to key facilities in the region, such as the EMASESA El Copero Environmental Complex, test plots with engineered soils, the Montemarta Cónica Technology Park, and the IRNAS-CSIC “La Hampa” Experimental Farm, where the solutions discussed could be observed in the field.
Nutrient recovery: circular fertilizers from livestock waste
One of the most heated debates surrounding the valorization of livestock waste concerns nutrient recovery , especially nitrogen, to reduce dependence on synthetic fertilizers. In the current context of supply crises, this issue has become extremely important.
The Spanish Veterinary Medical Association (OCV) has emphasized that Spain could recover between 200.000 and 400.000 tons of nitrogen annually if livestock byproducts, primarily 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 promoting 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 Veterinarians of Europe has already warned that it is a priority to reduce dependence on synthetic fertilizers linked to fossil fuels , advocating instead for 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 soils . Today, 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 for reversing 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 problems , it is essential to comply with a set of legal and technical requirements. In Spain, the R1001 operation for valorization in agricultural soils and gardens establishes the framework for this practice to be carried out with guarantees.
Operation R1001 is based on incorporating organic waste into the soil with a clear agronomic purpose : to provide nutrients to crops and increase soil organic matter, while properly managing the waste. To achieve this, 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, must be respected.
This Royal Decree establishes technical criteria for the application of waste and by-products in agriculture : dosage limits, quality requirements, traceability, application frequencies, analytical controls, and compatibility with fertilization plans. It also stipulates the obligation to prevent impacts on surface and groundwater, especially in areas vulnerable to nitrate pollution.
The autonomous communities complement this national legislation with 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 Regional Biomethanization Plan in Castile-La Mancha and the Catalan Digest Strategy and its 2024-2030 action plan.
This entire regulatory framework necessitates meticulous planning for waste valorization . Authorities require technical reports and management plans that justify the suitability of the waste, its quality, applicable dosages, and its compatibility with 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 waste , which has a high polluting potential 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 poultry 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.
Chicken manure comes from poultry farms and is composed mainly of bird droppings and bedding material. Due to the birds' slow 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 carefully.
In quantitative terms, it is generally estimated that the daily amount of manure and slurry generated is around 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 produce, and the importance of having robust management systems.
If these wastes are not properly treated, the environmental impacts are numerous : emissions of harmful gases and foul odors into the atmosphere, salinity problems or accumulation of heavy metals in the soil, 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 the farm itself. In the air, they can release gases such as ammonia and hydrogen sulfide, which not only generate unpleasant odors but also pose health risks to workers and animals.
In soil, the excessive or indiscriminate application of these residues can alter the pH , 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 waterways, the most serious problem is the leaching of nitrates and nitrites into aquifers and surface waters, which contributes to eutrophication and poses 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 : reducing waste generation as much as possible, improving the design of facilities to minimize wash water, optimizing livestock feed, and applying appropriate treatments to effluents so that they can be used for productive purposes without generating unacceptable impacts.
In this context, extensive livestock farming plays an interesting role as a system more integrated with the land , 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 elements , beating to homogenize the waste, and mechanical separation 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 undergoes sedimentation to remove sludge.
The sludge obtained through sedimentation can be reintroduced into the solid fraction for co-fermentation , optimizing overall waste management. Physical technologies such as dewatering or incineration also exist, although these typically involve higher investments and, in many cases, result in less added value to the final product, and are therefore used only in specific situations.
Regarding biological treatments, aerobic digestion is the basis of composting . In the presence of oxygen, communities of bacteria and fungi break down organic matter, generating carbon dioxide and transforming the initial mixture into a stabilized compost that is safer, with fewer pathogens and odors, and with very interesting agronomic properties as a soil amendment.
On the other hand, anaerobic digestion takes place in the absence of oxygen, usually in biodigesters . In 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 to produce electricity and heat , helping to reduce the farm's carbon footprint and improve its energy balance. Furthermore, if purified to biomethane quality , it can be injected into the grid or used as a renewable fuel for transportation or industrial processes.
Anaerobic digestion is particularly well-positioned as a tool for reducing greenhouse gas emissions , as it prevents the uncontrolled release of methane from the natural decomposition of waste and channels it toward useful energy production. At the same time, it allows for the preservation of most nutrients 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, administrations require detailed technical reports that plan the entire management of agricultural valorization: from the characterization of the waste to the doses per hectare and its integration into fertilization plans.
These reports usually include the identification of the residue and the receiving plots , the taking of samples and their analysis in accredited laboratories, agronomic studies of soils and crops, macronutrient balances such as nitrogen, phosphorus and potassium, and the preparation of thematic mapping using geographic information systems to delimit application areas.
In addition, a technical report is prepared describing the application procedures and justifying their compliance with regulations , along with assistance in the necessary administrative procedures to obtain permits or report activities. Specialized environmental companies offer these types of services to both producers of agri-food waste and 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 like Catalonia and 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 national regulations on waste and sustainable soil nutrition. This rigorous planning is key to making digestate a solution, not a new problem.
In parallel, the implementation of collective biogas plants is being promoted . These plants combine waste from several farms and, in many cases, co-digestion is carried out 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.
In short, when good technologies, regulatory compliance and planning are combined , livestock waste goes 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.