Not that long ago a field of maize was a rare sight in the British countryside. In 1973 there were a mere 8,000 hectares of the tall-stemmed crop growing in the UK. Today there is 25 times that amount. Around 200,000 hectares of maize fields make parts of our island resemble the farmlands of Iowa or Illinois.

This increase in maize planting has been driven by two agricultural innovations. The first is the adoption of maize as a common farm animal feed, as cattle and other livestock have been moved off grasslands and into barns. The second is the rise of anaerobic digestion (AD) plants, in which bacterial microbes are added to crops and slurries to create green gas, such as the nine we operate here at Future Biogas.

Naturally, we are big believers in the benefits of British maize. With its consistently high yields, both per hectare as a crop and per cubic metre of biogas, it has become the core feedstock of our AD plants. We also use rye, potatoes and sugar beet, but find maize to be the most efficient and profitable fuel crop.

However, the UK maize boom is not without its critics. They claim that, as an indigenous American, subtropical plant, maize is simply not suitable for the British climate and topography. The vigorous, starchy plant, they say, requires too much fertiliser to grow in this country, making it environmentally detrimental.

Another common criticism is that maize’s late growing season results in fields being left bare for too long, resulting in soil erosion. As maize is usually harvested late in the year, when British soils are often wet, detractors maintain that water runs off the surface of compacted and damaged fields, polluting waterways with pesticides and nutrients and, ultimately, causing floods.

At Future Biogas we take these criticisms extremely seriously. As green energy creators, sustainability is at the heart of everything we do. It would make no sense for us to rely on an environmentally destructive practice. Thanks to a decade at the forefront of the UK AD industry and investment in the best agricultural expertise around, we know that maize can be grown here in an eco-friendly and responsible fashion. It’s just a question of doing it properly.

Here are our counter arguments to the criticisms levelled against British-grown maize:

Climate

The reality of global warming is that maize is becoming more and more suitable as a UK crop each year.

We’re experiencing longer, hotter summers, to which maize reacts favourably. This is largely because it’s one of a handful of global crops that benefits from a special, turbocharged pathway for photosynthesis.

Photosynthesis is a process that uses water, carbon dioxide (CO2) and solar energy to synthesize sugars. Whereas most plants perform what is known as C3 photosynthesis, certain plants that have adapted to hot environments – like maize – perform a modified form known as C4. In a warmer climate it’s more efficient, meaning that the potential for future yields in our changing world is huge.

Fertiliser

The truth is that maize requires less fertiliser than common UK arable crops like wheat, sugar beet and oilseed rape, because it has a much shorter growing season.

Moreover, when maize is grown as a feedstock for an AD plant, a large percentage – or indeed all – of its chemical fertilisers can be replaced with eco-friendly green or natural fertilisers made from the plant waste leftover from the AD process, known as ‘digestate’.

Digestate contains high levels of available nitrogen. Combined with useful amounts of phosphate and potash, together with quantities of other nutrients and trace elements, it makes a fantastic fertiliser – and offers a great partner to artificial fertiliser. Using it improves the sustainability of farming by reducing emissions of greenhouse gases associated with fertiliser manufacture and by reconnecting nutrient cycles.

However, it should be noted that the application of digestate is not without its own risks. Digestate releases nutrients slowly, meaning they’re available to crops for a longer period. This can result in them being leached from the soil via rain or irrigation, causing groundwater contamination. At Future Biogas we mitigate against this risk by planting cover crops – like phacelia, vetch, ryegrass, grazing rye, barley and mustard, or a mix thereof – at the end of the harvest. Such off-season crops boost soil’s health, structure and its water retention capabilities.

Bare Fields

Maize has a very short growing period. Typically, it’s on the land for five or six months, which means the land can lie fallow for a long time. This can result in both soil erosion and degradation. Here is where cover crops are, again, of huge benefit.

To retain soil moisture and nutrients, our farmers plant green cover crops over winter. They help prevent soil erosion, because their root biomass holds onto the soil. They also capture residual nitrogen and prevent other pollutants reaching watercourses.

Soil Erosion and Flooding

If conditions aren’t right, the widely-spaced stems and shallow roots of maize leave the soil exposed to the elements and can allow water to run off the land. This, in turn, can lead to soil erosion and the depletion of good arable lands.

The reality is, this is only a prevalent problem in the west of the British Isles, where it’s hillier and rainier. Unfortunately, this is the area where maize was first grown in the UK, as animal fodder for local livestock farms. Soil erosion issues subsequently arose, because maize was being planted on steep slopes in a wet landscape.

At Future Biogas we have been very careful to locate our plants in the east of the country. We mainly work with farmers in East Anglia, where it’s very flat and much drier than the west, so rain run-off isn’t the same problem. What’s more, the soils are lighter and sandier – and so more suitable for maize.

Pesticides

Maize requires less than a quarter of the pesticides used on many other UK-grown crops. In this regard, it is, in fact, a very low input crop.

Efficiency

At Future Biogas we use a blend of the latest science and traditional techniques to make sure we’re as efficient as possible in our agricultural practice. This not only maximises the return on each harvest, but means we use as little land for maize growing as possible.

We use our extensive farming expertise and in-depth database to analyse each harvest in detail. The resulting data informs our planning for the next harvest. It helps us decide which particular varieties of maize should be grown in which areas, as well as the amount of digestate we should spread on specific fields.

We have become particularly adept at optimising the amount of dry matter in our maize crop, which is the cellulose-rich parts of the plant, like the stalks, that are key to high methane yields.

The Future

The truth is the risks of growing maize in the UK are more than manageable, with the right expertise. It’s about the intelligent management of the land: planting the right crop in the right place at the right time. If maize is planted in rotation in a suitably dry, flat and sandy-soiled location – with the use of natural suitable inputs (including digestate), winter cover crops and strategic thinking to maximise its yield – it can be farmed sustainably in the UK.

Its increased presence on British farmlands is just a small part of a much bigger picture. As our climate warms, the truth is that we can no longer rely 100% on traditional British crops. In a changing world, we must adapt to survive.

Melissa McClements

#ThatDot