Why we need to cut fertiliser use

Why we need to cut fertiliser use

Yes, fertiliser is really important, its a big part of the 'green revolution' that enables us to feed the world. Fertiliser runoff pollutes our waterways and excess fertiliser can pollute and deplete our soils. And, for farmers, if they use too much, its wasted. An expense they didn't need to make.

Summary: Yes, fertiliser is really important, it's a big part of the 'green revolution' that enables us to feed the world. But, you can have too much of a good thing. Fertiliser runoff pollutes our waterways, and excess fertiliser can pollute and deplete our soils. And, for farmers, if they use too much, it's wasted. An expense they didn't need to make.

Why this is important: Fertiliser is an expensive input for many farmers, sometimes so expensive they just cannot afford it at all. Given this, it is somewhat surprising that many farmers continue to over apply fertiliser, well past the scientific economic level. 'Ecological intensification practices' can reduce the application levels even further. This improves the economics for farmers, and helps the environment - even before we think about alternatives to synthetic fertilisers.

The big theme: Agriculture sits at the intersection of a number of UN Sustainable Development Goals (UN SDGs). Reforming agriculture is going to require massive social and economic change, and a lot of disruption - to production methods, to supply chains and to employment. It’s not clear (yet) that the political will to change fast enough really exists, which could mean faster and more dramatic change needs to come in the future.

Many farmers still over apply fertilisers. The reasons for this are complex. For many farmers it's a risk minimisation technique. If the recommended application is good, then more must be better. For others is caution. Farming is financially precarious, a bad harvest can be devastating.

But, whatever the reason, it's clear that as a planet we are using too much synthetic fertiliser, and that this overuse is leading to material damage to our environment. One obvious answer is get farmers who apply too much to reduce the rate at which they apply fertiliser. And for those who currently apply too little, to use other techniques, such as ecological intensification, instead. And of course, there are other technologies such as biologicals (but that's a topic for another blog).



The Detail


Summary of a report published in The Conversation

  • To sustain agriculture it is necessary to minimise the use of inputs like fertilisers, and support crop growth in other ways. One approach is through increasing ecological functioning within farms. This means enhancing relationships between different on-farm organisms, including crops, livestock, microbes, and wild plants and animals. Using these relationships to support crop yields is called β€œecological intensification”.

  • The study shows that ecological practices usually increased yields when added to a farming system. However, the benefits of crop diversification, fertility crops and adding organic matter were typically high when synthetic nitrogen fertiliser use was low. Often there was no benefit when nitrogen fertiliser use was high. This showed us that you can use either an ecological practice or a nitrogen fertiliser to increase yields. But if you use both together, the effect is the same as using either one.

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