The European Nitrates Directive was created to protect water from agricultural pollution, but today new nutrient recovery technologies are changing how livestock manure is managed.
Guest post by Fabiana Surace, CMO and Environmental Scientist at Cynomys
In recent years, livestock manure management has become one of the most widely debated topics in European agricultural policy. At the center of the discussion is the Nitrates Directive, a regulation introduced in the 1990s to protect water quality, but which today must confront new technologies and the growing interest in the circular economy.
Modern agriculture uses large amounts of nitrogen to sustain crop productivity. However, when nutrient inputs exceed plant requirements, part of the nitrogen can be converted into nitrates and leached into surface and groundwater.
This occurs because in soil ammoniacal nitrogen tends to bind to clay particles and organic matter, while nitrates remain dissolved in soil water and are therefore much more mobile. For this reason, they can easily be transported toward aquifers through leaching.
This phenomenon can contribute to the eutrophication of aquatic ecosystems and to the contamination of groundwater used for drinking water supply. Eutrophication, in simple terms, is the process by which an aquatic ecosystem is altered due to excessive nutrient enrichment, mainly nitrogen and phosphorus. This nutrient overload causes abnormal proliferation of algae and aquatic plants which, when they decompose, reduce dissolved oxygen (anoxia), leading to the death of aquatic fauna and degrading water quality.
To address this problem, in 1991 the European Union introduced Directive 91/676/EEC, known as the Nitrates Directive, with the aim of reducing water pollution caused by nitrates from agricultural sources and preventing further contamination.
The Nitrates Directive and water protection
The directive was created following the recognition that agriculture is one of the main diffuse sources of nitrates in water, mainly due to the use of nitrogen fertilizers and the management of livestock manure.
For this reason, Member States are required to monitor the quality of surface and groundwater and to identify Nitrate Vulnerable Zones (NVZs): areas of land that drain into waters already polluted or potentially at risk of nitrate pollution.
Within NVZs, specific Action Programs must be implemented, establishing a set of rules on nitrogen management in agriculture and on the agronomic use of livestock manure.
The 170 kg nitrogen per hectare limit
One of the most well-known measures of the Nitrates Directive concerns the management of livestock manure.
In Nitrate Vulnerable Zones, the regulation establishes that livestock effluents cannot supply more than 170 kg of nitrogen per hectare per year.
This limit does not apply to all nitrogen applied to fields, but only to nitrogen originating from livestock manure such as slurry and solid manure.
In other words, the directive does not limit the overall use of nitrogen in fields, but only the nitrogen coming from livestock effluents. Over time this has generated debate: in some situations farmers may be forced to reduce the use of available manure and instead rely on mineral fertilizers.
The objective is to reduce the risk that excess nitrogen will be converted into nitrates and leached into groundwater and water bodies.
Over the past thirty years, the implementation of the directive has helped limit nutrient losses and improve water protection across Europe.
The challenge for intensive livestock farms
The problem arises when an imbalance develops between the number of animals raised and the agricultural land available for manure spreading.
For many livestock farms, the limit of 170 kg of nitrogen per hectare can represent a management challenge.
When the number of animals is high relative to the available agricultural land, the amount of nitrogen contained in the manure produced by the farm may exceed the quantity that can be spread on fields within the limits established by the regulation.
In these cases, farmers must adopt alternative strategies, such as:
- delivering manure to treatment or biogas plants
- transferring it to other farms with more available land
- treating it with technologies that allow nutrients to be recovered and separated
In recent years, precisely thanks to the development of new manure treatment technologies, a new perspective has emerged for nitrogen management in agriculture.
From manure management to the circular economy
Technologies such as solid–liquid separation, anaerobic digestion, ammonia stripping, or membrane systems now allow the recovery of nitrogen contained in livestock manure and its transformation into fertilizers with a higher share of mineral nitrogen, making them easier to manage from an agronomic perspective and similar, in behavior, to “synthetic” fertilizers.
For example, ammonia stripping systems allow nitrogen to be recovered in the form of ammonium salts usable as fertilizers, while membrane or evaporation systems allow nitrogen to be concentrated into liquid fractions that are easier to manage agronomically.
These solutions make it possible to valorize manure, transforming what has traditionally been considered an environmental management problem into a potential agricultural resource.
It is in this context that the concept of RENURE emerges.
RENURE: fertilizers from livestock manure
RENURE is the acronym for Recovered Nitrogen from Manure and refers to fertilizers obtained from the treatment of livestock manure with characteristics similar to mineral fertilizers.
The idea behind the European proposal is that some products derived from treated manure could be used as fertilizers without being considered equivalent to traditional livestock effluents.
If authorized by Member States, the use of RENURE fertilizers could allow farmers to exceed the 170 kg of nitrogen per hectare limit, provided that specific conditions and environmental safeguards are respected.
The objective is twofold:
- to valorize nutrients already present in agricultural systems
- to reduce Europe’s dependence on synthetic fertilizers
Agritech innovation and nutrient management
Nitrogen management is set to become increasingly central also for the agritech sector. Environmental sensors, soil monitoring systems, agronomic models, and digital technologies can help optimize nutrient use and reduce losses to the environment.
In this context, manure management and nutrient recovery represent one of the most promising areas for technological innovation in agriculture.
A challenge between environment, agriculture, and innovation
Nitrogen management represents one of the most complex challenges for European agriculture.
On one hand, it is necessary to protect water quality and aquatic ecosystems; on the other, it is essential to ensure the economic sustainability of farms and to valorize the resources already present within production systems.
The discussion around RENURE sits precisely at the intersection of environmental protection, technological innovation, and the circular economy.
In the coming years, it will be important to understand whether and how these solutions will succeed in reconciling the objectives of the Nitrates Directive with the needs of an increasingly efficient and sustainable agriculture.
Continuous environmental monitoring of greenhouse gases and harmful gases — not only for animals but also for farmers — can represent one of the useful activities to keep emissions in livestock buildings under control and maintain a good balance in manure storage or treatment tanks, ensuring that the final product applied to fields has high value and low environmental impact.
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