Water companies team up with farmers to capture excess nitrate from soil and water


Affinity Water and Cambridge Water have announced they will work with 18 farms using a cover crop scheme, across 800 hectares.

The aim of this project is to capture 37.4 tonnes of nitrate which could otherwise leach into the chalk aquifers that are used to supply drinking water.

Cover crops play an important role in improving farm productivity and enhancing the natural environment.

These crops, grown in the autumn/winter months between cash crops, are an excellent way to capture excess nitrate left in the soil.

Without a cover crop, this nitrate has the potential to leach into the aquifer or into nearby rivers, increasing the nitrate concentration which would then require water treatment.

Shaun Dowman, Agricultural Adviser at Affinity Water, commented on the partnership: “This scheme will deliver 800 hectares of cover crops this winter in our catchments which have a range of benefits including: protecting water quality, improving soil health and water infiltration, capturing carbon and benefiting farm wildlife such as farmland birds and pollinators.

“Next year we plan to hold another auction and to set further ambitious targets and broaden our offer beyond just cover crops.

“We will learn from this year and will endeavour to calculate as much of the wider ecosystem benefits of this scheme as possible.”

Aside from the benefits to water quality, growing a cover crop can also help build organic matter in soils, protect them from erosion and can attract farmland birds and other wildlife to increase biodiversity.

Affinity Water is working with The Farming and Wildlife Advisory Group East and Cambridge Water in North Hertfordshire and South Cambridgeshire to fund the growing of cover crops through the EnTrade auction process.

Jake Rigg, Director of Corporate Affairs and Communities at Affinity Water, commented: “This is a win, win, win situation – we are investing for the long-term continuation of quality water, farmers receive a payment for delivering a service that protects and enhances their natural assets, and the environment benefits as we capture residual nitrate which may have otherwise leached into the water.

“Cover crops are also fantastic for our planet – often called ‘pop-up rainforests’ for their ability to capture carbon from our atmosphere.

“This is a very strong result in only our second year of this mitigation programme.

“Enhancing natural capital in our catchments, using the EnTrade platform, is just one of the initiatives which Affinity Water is progressing to provide high quality water and, with the help of farmers in our region, take care of our communities’ environment now and for future generations.”

In 2019/20, the water companies worked with 11 farms in North Hertfordshire and South Cambridgeshire to fund the capture of 24 tonnes of nitrate from 488 hectares of land.

Building on the success of last year’s scheme the water companies plan to collect 50 percent more nitrate in the 2020/21 growing season, working with 63% more farms.

The auction’s success is despite COVID-19 (resulting in online remote contact only) and with the help of the Farming and Wildlife Advisory Group East (FWAGE) who promoted the auction with the local farmers.

Caroline Cooper, Director of Asset Strategy at Cambridge Water, added: “It’s a fantastic result, which will see us working with even more farms than last year.

“We’re pleased to be working in partnership with Affinity Water, Entrade and FWAGE to deliver this innovative scheme.

“By working together we can ensure that we work with more farmers to protect water quality and the environment, now and in the future.”

Nitrogen (which when applied to the land is converted to nitrate) is an essential component of fertiliser and is key to crop yield.

It is also an expensive item for farmers and not one they want to waste or lose to the environment.

The efficient use of Nitrogen has improved dramatically over the past 30 years but some practices such as leaving land bare over the winter months may increase the risk of nitrate leaching with consequences to water supplies and the environment.

Our catchment management teams work with landowners on a number of targeted projects where water quality can be improved at source, reducing the reliance on expensive and energy intensive water treatment.

Where possible, any investment from the water companies in the catchments should have multiple benefits for water quality, sustainable food production, the environment and our customers.

EnTrade reverse auctions are run via an online platform that facilitates environmental improvements.

The EnTrade reverse auctions are one of a number of investments in the long-term mitigation of nitrate and enhancement of natural capital in our catchments.

This year’s payment to farmers is on average £109 per hectare, with higher payments made to those crops that capture more nitrate, such as oil radish, and those that are planted earlier.

Jeremy Graham, scientist at EnTrade, added: “This is the second year we have worked with Affinity Water and Cambridge Water to drive reductions in nitrates from farmland, following a successful pilot in 2019 where 24 tonnes were prevented from leaching into local watercourses.

“EnTrade was designed to improve the collaboration between beneficiaries of environmental services, such as water companies, with those who can help to make a huge difference, such as farmers.

“We commend Affinity Water and Cambridge Water for taking this innovative approach to reduce nitrate levels in their catchment and for supporting their local farmers in the process.”

Both water companies provide regulatory compliance with the Drinking Water Inspectorate and the Environment Agency.

This supports the Water Industry National Environment programme.