For centuries, technological progress has meant substituting artificial products for natural ones. Timber, clay, reed and wool have been replaced with steel, concrete and synthetic fibres. However, as concerns about global heating and sustainability are rising, we are seeing a return to natural materials.
Garden plants grow up
In the search for economically sustainable ways of contributing to net zero, farmers are experimenting with plants which can:
- consume less (or actually generate) energy;
- reduce the use of chemicals;
- remove carbon from the atmosphere;
- improve soil health, water retention and biodiversity.
They are exploring industrial uses of plants which we know better as garden ornamentals, like miscanthus, bamboo and pauwlonia. All are fast-growing and all absorb carbon faster than most agricultural crops and forestry. All can substitute for more environmentally damaging materials.
But, of course, nothing will happen unless the farmer can make a living from growing them.
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Uses of miscanthus
Miscanthus has been described as “a grass that thinks it’s a tree”, because of its great height (3-4 metres). At present the main use in this country is for burning as a biofuel. The Snetterton Renewable Power Station in Norfolk prefers it to cereal straw as a fuel because of its consistent quality, higher calorific value and predictable supply from year to year. They would certainly use more if there was more being grown.
But miscanthus has many other uses, including papermaking, and making construction materials like lightweight building blocks, heat and sound insulation and fireproof boards. It will not hold up a school roof, but it will block the sound of traffic or noisy neighbours. It can be used to create bioethanol, and will also remove heavy metals from contaminated land, returning it to useful agricultural health.
The plant
Miscanthus absorbs CO2 five times faster than fast-growing trees. It has a permanent root (the “rhizome”), from which it regenerates new growth repeatedly, like lawn grass, when the stems are cut down. This means that, although some of the carbon it absorbs during growth is released when the stems are burned as fuel, much remains locked below ground.
After allowing for harvesting, baling, transport and – yes – burning, a mature crop will still lock up 2.3 tonnes of carbon per hectare every year. It is also good for soil health, because the ground in which it grows is not ploughed: the leaf litter is allowed to lie and decay, which encourages the development of natural organisms in the soil.
Miscanthus takes two years to establish, and for the farmer to recover the initial costs. But from then onwards, it can be harvested annually for more than 20 years. It will grow on any kind of soil and requires no artificial fertiliser. Its only use of chemicals is to keep down weeds during the first two years while it establishes itself. For the farmer it is a trouble-free crop, resistant to wet, pests and diseases, and only requires attention for one month of the year, at time when there is little other arable farming activity. Terravesta estimate that, once established, it yields £750 a hectare profit a year.
Miscanthus in Norfolk
At Bintree in Norfolk, Algy Garrod grows ten hectares of Miscanthus alongside other crops. He comments:
Miscanthus is useful because it will grow on poor and waterlogged soil, which is difficult for other crops. Since it doesn’t need spraying or cultivating I can plant it in small and awkwardly shaped fields, and parts of fields which can’t be worked with my big crop sprayers. I also raise game birds for shooting. For this, it provides good cover without the erosion and soil damage which maize produces.
National developments
William Cracroft-Eley has been growing miscanthus in Lincolnshire for 17 years and is the chair of Terravesta, a firm which promotes and supports miscanthus development, and is a major supplier to the bioenergy power stations at Snetterton in Norfolk and Brigg in Lincolnshire. He says that there are now over 5,000 hectares of miscanthus growing in the UK, but cautions:
This is not the solution to all our problems. Achieving net zero will not be a single “big bang”. It will involve many relatively small innovations, but this is one really important one.
Miscanthus is a crop which complements conventional agriculture. It makes good use of land which would otherwise be unproductive, with yields which are less variable from year to year than other crops. It needs attention only at times when other farming activity is low. And for farmers, demand for the product exceeds supply, and it provides a steady long-term income.
For the farmer, it takes three years to begin to make a profit, but after that the income is predictable for another twenty years. If they can be persuaded to take the long view, this would be a real step towards a healthier environment and net zero.
