Why Greenshank are not recommending land abandonment for nutrient neutrality

November 23, 2022

Back in 2019, when the requirement for Nutrient Neutrality had begun to affect the Solent region, Local Planning Authorities and the development industry on the South Coast were scratching their heads on how to conform to a whole new set of regulations. Developers who had made huge investments and were nearly through the planning process had to do a mad scramble to abide by the new rules by finding ways to offset the nitrogen pollution that can result from new development.

Some savvy landowners in the Solent realised that a quick way to ease the problem (and make some money in the process) was to offer up their land to developers. In exchange for stopping farming, they could make many times what their land was worth in a few short months. All they had to do was agree to stop farming on their land, and in the process stop the input of nitrogen fertilisers that, along with other nitrogen sources, are the driver behind Nutrient Neutrality in the Solent .  

So started a flurry of landowners offering nutrient mitigation solutions via land abandonment.  

What happened in the Solent was the only available response at the time. Roll forwards and we are in a very different place, with many more solutions available to help the development sector achieve nutrient-neutral development.

With these new solutions available, we at Greenshank are happy to say that we don’t recommend land abandonment schemes. We don’t believe they are the answer because they fail three very basic tests:

  1. Is it good for communities and the economy?
  2. Is it a sensible investment?
  3. Are there alternatives?  

We believe land abandonment fails all three of these tests.

Is it good for the local community?  

On average, it takes around 40 ha of land to provide nitrogen mitigation for around 330 houses. At present, it is estimated that 100,000 houses are stalled because of Nutrient Neutrality. Assuming you could viably provide nutrient mitigation for all these houses (more on viability below), this would mean taking over 12,000 ha of land out of agricultural production!  

Taking farmland out of production means fewer jobs, less locally produced food and higher food prices. At a time when global supply chains are stretched and local communities everywhere are feeling the pinch, it is more important than ever that we look to preserve local jobs and local economies.  

Is it a sensible investment?  

Of the 27 catchments in England and 5 catchments in Wales that are affected by Nutrient Neutrality, three need mitigation for nitrogen only. The others all need either nitrogen and phosphorus mitigation, or only phosphorus.

If we look at data used to calculate the nutrient loads that come from different types of farming in areas of the Norfolk Broads catchment, nitrogen can output between 18 and 405 times the amount of phosphorus per hectare. A hectare of agricultural land can provide phosphorus mitigation for about 1 house on average (and often less). Compare this with about 8 houses per hectare of land for nitrogen mitigation and we can see that the costs for mitigating phosphorus through land abandonment don’t stack up, not to mention the problems taking so much land out of agricultural production would cause for local communities.      

In the three nitrogen-only catchments, land abandonment schemes can still seem like a sensible investment, but they fall over pretty quickly when we start to look at alternative mitigation measures.

We can now recommend wetlands and land management techniques that can provide nutrient mitigation for nitrogen and phosphorus, with a fraction of the required land take. Because phosphorus mitigation can’t be viably achieved using land abandonment, phosphorus mitigation is also much more in demand. This is driving a premium on the cost of phosphorus mitigation that sees the cost per house sometimes being touted at 4x that for nitrogen mitigation! But what really leaves land abandonment techniques underwater (pun intended) is that a correctly delivered wetland or land management solution can deliver 5-10x the return on investment of an abandonment scheme while preserving 80-90% of the land. And all these considerations don’t account for the opportunity cost of not farming land.  

Are there alternatives?

By now it should be quite clear that the answer to this question is ‘yes’. As mentioned above, we can now recommend wetlands and land management techniques for nutrient mitigation. This was not the case back in 2019 when Nutrient Neutrality first hit the Solent.

Guidance is forthcoming on how to successfully deploy wetlands and land management techniques for nutrient mitigation. The land management guidance has been co-authored by Dr Gabriel Connor-Streich of Greenshank Environmental, so we know what can be done and how to do it. Picking the right solutions in the right places can help to provide the nitrogen and phosphorus mitigation that is needed to get the development sector moving again in areas affected by Nutrient Neutrality. We can do this without sacrificing huge tracts of agricultural land, and local communities, while embedding another pillar of sustainability in new development.  

If you are a landowner or developer looking at options for mitigation, we have delivered projects on mitigation for Natural England, councils, local government and private companies. Drop us a message here to find out more.


Kim Connor Streich

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