United Utilities is partnering with Cheshire farmers to grow biomass crops in its groundwater safeguard zones as a way of reducing nitrates leaching into groundwater.
The water firm is currently running a trial on 10 hectares of catchment land, but grants will be offered to any eligible farmer who is interested in growing a hybrid variety of Miscanthus, called Terravesta AthenaTM.
United Utilities is funding 70 per cent of the start-up costs, including purchase and planting, and will be monitoring the impact of the crop on nitrate leaching with porous pots. Nitrogen can leach into groundwater when it rains and adversely affect the raw water quality in the underground aquifers.
United Utilities catchment advisor, Veronika Moore, explained: “Miscanthus doesn’t require fertiliser during its lifetime (just a small amount to help aid establishment), because it retains a large proportion of the nutrients in the rhizomes rather than in the biomass. Therefore nitrogen and nutrient requirements are very low.”
The market for biomass crops – crops which are grown specifically to be harvested and burnt in power stations, combined heat and power (CHP) units or heating systems – is increasing. This is in response to a number of power and heat projects being developed across the UK which use biomass, including Miscanthus.
Miscanthus species are woody, perennial, rhizomatous grasses, originating from Asia, which have the potential to give very high yields (14 oven dry tonnes per hectare per year) under UK conditions.
Miscanthus can be used to produce heat, CHP or electric power on a range of scales from large power stations, requiring hundreds of thousands of tonnes of biomass annually, to small-scale systems (on-farm or single building) requiring just a few dozen tonnes during winter months.
Ben Booth, from Miscanthus specialist firm, Terravesta, who supplied and planted the crop, explains that it has many environmental benefits. “Miscanthus is perennial, producing a crop every year, which not only provides habitat for above and below ground species, it helps to boost soil health, and it increases soil organic carbon. In fact, a study from the Institute of Biological Environmental and Rural Sciences (IBERS) at Aberystwyth University concludes that Miscanthus can grow well in waterlogged and flood-prone areas. It also provides much needed soil stability, and crop yield is not affected by excess water.”
As well as energy, Miscanthus is also used as high value equine bedding and sustainable composite materials for markets such as the production of biodegradable plastics and fibres for car parts.
Veronika Moore added: “Miscanthus is planted in spring and, once planted, can remain in the ground for ten to fifteen years.
“First year growth is insufficient to be economically worth harvesting. New shoots emerge around March each year, growing rapidly in June/July, producing bamboo-like canes.
“The Miscanthus dies back in the autumn. The leaves fall off, providing nutrients for the soil and suppressing weed growth the following year, and the canes are harvested in early spring.
“This growth pattern is repeated every year for the lifetime of the crop, and the annual harvest gives an annual income to the farmer.”
Miscanthus spreads naturally by means of underground storage organs known as rhizomes. However, spread is slow and there is little risk of uncontrolled invasion of hedges or fields. These rhizomes can be split and the pieces re-planted to produce new plants. All propagation, maintenance and harvest operations can be done with conventional farm machinery.
United Utilities’ southern area catchment team is responsible for delivering a catchment management scheme that aims to prevent the contamination of raw water at source, reduce the pressure on treatment processes, and bring wider benefits to nature at the same time. The aim of catchment management is to protect and enhance the water environment through managing the surrounding land.
The Environment Agency has designated ten drinking water safeguard zones in and around Cheshire. These zones are drinking water catchments where water quality in rivers, boreholes or groundwater is deteriorating and is becoming harder to treat, due to human activities on the land. Safeguard zones can be used to target measures, advice and incentive schemes for landowners and managers to help improve water quality.