Natural fertilisers – the key to reducing on farm carbon footprint?

With constant scrutiny from government, food brands, social media activists – not to mention an entire payments system based around the environment – it is hardly surprising many farmers are feeling the strain when it comes to reducing their emissions.

Of course, this is completely necessary and all industries must strive for continual improvement when it comes to sustainability and the future of the planet.

But farmers suffer the difficult task of balancing producing enough food to feed a growing population with the use of crop inputs, some of which are extremely energy intensive to make. It’s a basic formula – use less of the latter and you get less of the former – and that’s where the conflict arises.

But is that always the case? It is well known that ammonium-based fertilisers require a huge energy input to manufacture, but is this true of others? Is there a way to significantly reduce a farm’s carbon footprint with a relatively modest change in a nutrient programme? You may be surprised to learn that a small tweak could result in a large cut in emissions. That is good for the environment, the consumer, and for farming.

Synthetic vs natural fertilisers

With most synthetic fertilisers, it is the manufacturing process that is responsible for the bulk of their carbon footprint. The fact is, making synthetic fertilisers requires a huge energy input, most of which is currently derived from fossil fuels.

This also makes them particularly vulnerable energy price increases, especially during times of serious global turmoil, as many are currently finding out to their cost.

Couple this with the fact that many synthetic fertilisers are highly susceptible to leaching, and you find that much of the energy used to create these inputs is wasted. It is a significant problem for the industry, and one there is mounting pressure to solve.

But contrast this with a natural fertiliser and you start to see a possible solution emerge.

By natural fertilisers, we don’t just mean manures and slurries produced by livestock, but mineral nutrients as well. By minimising the manufacturing processes involved in creating fertilisers, carbon emissions are naturally cut, and that is good news for all, including the farmer’s bottom line.

Polysulphate – a case in point

ICL’s Polysulphate is a case in point. Polysulphate is mined from 1,200m below the North York Moors in Boulby – the only mine the world to produce it.

It is extracted in its raw form as a rock called Polyhalite, and to turn that into Polysulphate, it is simply a case of crushing and screening it. This process also takes place at the mine, after which it is ready to be sold either as a straight, or mixed into blends.

Polysulphate consists of sulphur (48%), potassium (14%), magnesium (6%) and calcium (14%), all of which play vital roles in promoting plant health including facilitating the uptake of nitrogen, aiding photosynthesis, rooting development, yield and tip development.

It also benefits from a prolonged release mechanism, releasing its nutrients over a 50-60 day period, meaning it continues to provide nutrients to a crop long after it has been applied, in line with the plant’s requirements.

Sixty per cent of its nutrients are given up in the first 12 days after application, however, helping to facilitate plant emergence.

Global warming potential

So, what does all this mean in the real world?

Global warming potential (GWP) is a measure of a product’s potential to contribute towards global warming. Put simply, the higher a product rates on the GWP scale, the worse its impact on the environment.

Due to the lack of chemical or industrial processing, Polysulphate has an extremely low GWP compared to other fertilisers, measuring just 0.0377 kg C0₂e per kg of product. What this means is that every kilogram of Polysulphate created and delivered to a storage facility releases the equivalent of 0.0377kg of carbon dioxide, the standard greenhouse gas used to quantify environmental impacts.

By comparison, ammonium sulphate has a GWP of just below 0.6 kg C0₂e per kg of product – 16 times higher than Polysulphate. Ammonium sulphate nitrate weighs in at more than 0.8 and ammonium nitrate scales the dizzy heights of almost 1.2 kg C0₂e per kg of product.

Seen in this light, Polysulphate has a much reduced carbon footprint than all synthetic fertilisers.

It doesn’t end there!

But it is not just in the manufacturing process, or lack of it, that the savings are made.

Polysulphate is produced in the UK. It doesn’t have to be imported in bulk from countries thousands of miles away, so the emissions associated with storage and logistics are significantly less than those fertilisers that do.

Also, the prolonged release mechanism means the farmers can harvest all the benefits of the fertiliser from a single application, potentially reducing diesel use. As Polysulphate releases it nutrients over an extended time, it will continue feeding the crop throughout its growing cycle, while at the same time, reducing leaching.

Single source of nitrogen

Many of you might now be saying ‘Polysulphate doesn’t contain nitrogen, meaning we still have to apply nitrogen, which has a high carbon footprint’, and we understand. That is certainly the case.

But Polysulphate enables farmers to apply a single source of nitrogen rather than doubling up with applications of ammonium nitrate, ammonium sulphate, as well as additional potash applications and others. Although it by no means completely eradicates the carbon emissions generated by crop inputs, bringing Polysulphate into a nutrient programme enables it to be streamlined and made more efficient, both in terms of the overall impact of the nutrients themselves, and by minimising the application process.

It also facilitates plants to take up nitrogen more readily, meaning the N you do apply is used more efficient, potentially leading to an overall reduction in nitrogen usage.

Although not a complete solution to reducing the environmental impact of crop inputs, every little bit will surely help. With its extremely low carbon footprint compared to manufactured, synthetic fertiliser, all evidence suggests adopting Polysulphate into your nutrient programme will have a significant, positive impact on the overall sustainability of your farm business.

To find out more about Polysulphate, including advice on how and when to apply it, email plantnutrition@icl-group.com