Renure only limits the use of fertilizer in our country

The discussion and reporting about manure mainly focuses on what the farmer can dispose of and at what cost. By focusing so one-sidedly on the short term, you lose sight of the bigger picture. Namely what form of agriculture you want and how you ensure that the world population has enough to eat with as little adverse impact on the environment as possible.

Renure (recovered nitrogen from animal manure) is now often presented as the 'holy grail' because it would lead to significantly less fertilizer use. That claim only applies if you mention that you will then use less fertilizer in the Netherlands. Worldwide, it does not lead to less use of fertilizer. Concentrates are grown with the help of fertilizer, and we import a lot of it.

The climate problem and the need to use significantly less CO2 does not stop at the Dutch border. It is therefore better to discuss why we supply nutrients and where they come from. Only then can we look at the total picture and also take climate and groundwater quality into account in the considerations we make. And by applying fertilizer in the right way and in the right amount, reduce its use.

To get straight to the point: combined use of organic manure and mineral fertilizers produces better harvests with less leaching in more intensive crops. This use therefore makes an important contribution to the goals of the Water Framework Directive. It is now highly uncertain for large parts of the Netherlands whether these objectives can be achieved by 2027. Which brings up the next problem. And the potential is even greater than the manure piles for which short-term solutions are now being sought.

For those who don't deal with this on a daily basis, here's another reminder. Just like people, plants need nutrients (=food) to grow. They extract these from the soil.

source: Fertilizers Europe

The soil stock of nutrients varies greatly per soil type, how it was fertilized in the past and how much has been extracted from it. For example, peat naturally has a high nitrogen supply capacity, while this is very limited on sandy soils. By supplying organic fertilizer, new nutrients (nitrogen, phosphate, potassium, magnesium, etc.) are supplied. This can be in the form of animal manure or vegetable material. This also potentially enriches the organic matter content of the soil.

Washout
However, an important part of these nutrients in organic fertilizer must first mineralize (= digest) before they can be absorbed by the crops. This mineralization process is highly dependent on weather conditions and soil temperature.

The crops that the farmer wants to grow have their own nutrient requirements that also vary over time. And that usually does not match the mineralization process.

source: Fertilizers Europe

Simply put, if you supply so much organic fertilizer that you can meet the peak nutrient demand, the mineralization process that continues outside this peak demand will lead to a supply of nutrients that cannot be absorbed by the cultivated crop. And that potentially leads to leaching into the groundwater. Something we must limit as much as possible. This is why so-called green manures or catch crops are mandatory sown under or after the harvest of the cultivated crop in order to capture as much of the released nutrients as possible for the next growing season.

Mineral fertilizers are much more immediately available and can therefore be used at the start of the season when the mineralization process has not yet started properly due to low temperatures, or during peak demand, to provide the plants with the right amount and composition of nutrients.

Renure
From these agricultural aspects, it is also important to look at the role of the upcoming Renure products. The European Commission has indicated that it recognizes animal manure that has been processed using a limited number of techniques as mineral fertilizers. This means that these fertilizers can be used in addition to the soon applicable maximum of 170 kg nitrogen per hectare from animal manure. A maximum of 100 kilos of N from Renure products per hecatere has been set. The motivation for intensive livestock farming is cost reduction compared to the alternative of removing/exporting manure. For arable farming, in addition to the cost price of Renure, the agricultural value will mainly determine the sales potential. In contrast to grassland, for example, spreading mineral concentrate (large volume of water with 1-3% nitrogen) can be problematic once the crop has emerged.

Climate
An important consideration for Minister Adema to focus on Renure is the potential savings on fertilizer use in the Netherlands. The production of fertilizer is associated with a lot of CO2 emissions. We are working hard to reduce this, and as a result emissions have been halved over the past thirty years and will continue to fall drastically in the near future with the use of green energy and CO2 capture and storage.

The image below provides insight into how the ratio of animal manure and fertilizer use on mown grassland shifts with the new regulations. The starting point here is the situation in which the Netherlands still had a derogation that applied until recently, which allowed the application of up to 250 kg N/ha from animal manure, supplemented to the crop standard with artificial fertilizer. It was then made clear what happens if the derogation expires, the generic fertilizer discount that comes into effect as a result of the designation of so-called Nutrient Contaminated areas and the admission of Renure products up to 100 kgN/ha in addition to the 170 kg N/ha from animal manure .

source: Fertilizers Netherlands

You clearly see a significant decrease in the amount of fertilizer in this calculation example, so it's a piece of cake, you might say. But 2 questions are missing from this picture...

1. Where does the nitrogen from animal manure come from?
2. Does less manure export lead to more fertilizer use abroad? (and how much extra energy and greenhouse gas emissions are involved in processing manure)

The answer to the first question is that roughly 2/3 of nitrogen now comes from imports of concentrates grown abroad with artificial fertilizer and 1/3 from fertilizer use in the Netherlands. With maximum use of Renure, this shifts to 87% from concentrates and 13% from fertilizer use in the Netherlands.

In answer to the second question, less export of animal manure to neighboring countries means that they will use proportionately more artificial fertilizer to provide their fertilization. The process of processing fertilizers into Renure so that they can be applied in the Netherlands costs energy but may save transport kilometers compared to exporting abroad.

As the Netherlands, we are becoming more dependent on the import of concentrates and fertilizer use outside Europe for our nutrient input and we will not achieve a global reduction in fertilizer and greenhouse gas emissions.

With these comments, am I against the use of Renure fertilizers? No, in a number of situations Renure can provide the agricultural sector with the financial relief it desperately needs now. However, applying unprocessed animal manure is more efficient but requires an inevitable extensification of livestock farming.

The argument that Renure leads to significantly less fertilizer use is only correct if you add 'in the Netherlands'. In my view, the amount of CO2 saved worldwide is zero, as the animal manure was also usefully used in agriculture and saved on artificial fertilizer use abroad.

How can you save on fertilizer use?

• More efficient fertilization according to the 4 correctnesses (right fertilizer, in the right place, in the right quantity and at the right time);
• Lower livestock farming intensity
• Transition to a more plant-based human diet;
• Use of more leguminous plants.

As far as I am concerned, this is the future-proof path to more sustainable agriculture.

Reinier Gerrits

Reinier Gerrits (1972) is director of Meststoffen Nederland. In this role he represents manufacturers, importers and distributors of fertilizers.

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