Water quality improvements are welcome, but there’s more to do

Results from ongoing raw water quality monitoring of local rivers illustrated the improvements that had been made in managing risks from pesticides in particular, while modelling by Anglian Water quantified some of the reductions in nutrient loading and sedimentation that farmers in certain catchment areas had achieved by taking up activities covered by its Farm Innovation Grant.

However, speakers warned that heavy rainfall events still posed serious challenges to water quality, particularly for soil run-off and nitrate pollution risks.

“Nitrate can’t be removed from water, so if concentrations in raw water are too high (above 50mg/litre), this limits the amount that can be abstracted from rivers,” Essex & Suffolk Water’s Stephen Derbyshire said.

Results from monitoring of the River Stour in 2024 showed two nitrate spikes recorded up to late November, one in May and the other in October, both following periods of heavy rain. Turbidity, which is caused by soil particles clouding water, could be similarly problematic, he noted.

“Great progress has been made managing pesticide risks, but water quality can still be an issue in wetter months, particularly after heavy rainfall.”

Farmacy agronomist, Jim Woodward, added: “When we started this event 15 years ago, the focus was very much on managing the risks around agrochemicals and water. Over that time, farmers have made some real improvements, but there are still areas to work on, which is why this event has shifted its focus more towards nitrate and soils.”

Building water resilience

Improving aggregate stability, infiltration, and the water holding capacity of farm soils were highlighted as key ways of addressing many of the challenges faced, and could be “win-wins” for farmers, the environment and water quality.

“Our aim is to get soils into a condition where they can percolate water down through the profile and store it in the aquifer, rather than water running off the surface into watercourses,” Hutchinsons head of soils, Ian Robertson said. “Growers should be striving towards more water retentive soils.”

There were many different ways to do this (see panel on the right), but building organic matter and humus content was key, he continued. Indeed, US research suggested that a 1% increase in soil organic matter could increase water holding capacity by around 62,000 gallons (279,000 litres) per hectare, equivalent to 27mm of rainfall. That could potentially provide an extra 4.65 days of grain fill, worth almost 0.8t/ha in extra yield potential, where water availability was a limiting factor, he said.

It was crucial to tailor any actions to individual soil types and situations though, therefore Mr Robertson urged farmers to start by getting a comprehensive soil analysis done, such as the Hutchinsons Gold soil test.

“Water holding capacity is primarily determined by soil texture, i.e. the sand, silt, clay fractions. But how those elements are arranged to form the soil structure is key, and that depends on many different chemical and biological interactions, cultivation policy, and cropping. It’s vital to properly assess soils to understand how they will perform and identify the most appropriate ways to manage it.”

The Gold soil test is still available free to farmers in certain priority catchment areas in Essex and Suffolk (River Stour, Layer Brook and Roman River), courtesy of Essex & Suffolk Water.

Other funding options

The Sustainable Farming Incentive (SFI) includes a number of different actions focused around building the health and resilience of soils, and Mr Woodward urged any farmers not yet in the scheme to sign up.

“It’s not the finished product yet, but the SFI is the future for how farmers will receive funding.”

Many water companies also offer specific grant funding opportunities to address raw water quality risks, such as Essex & Suffolk Water’s Field to Tap scheme, and Anglian Water’s Farm Innovation Grant. Both schemes are currently closed to new applications, but are due to reopen in the spring.

Five steps to build soil resilience

• Test soils to understand soil physics, chemistry and biology and identify any issues or limiting factors, and the most appropriate management options
• Address any imbalances in pH or soil chemistry (e.g. high magnesium content making soils tight can be rectified with gypsum)
• Increase soil organic matter and humus (broken down organic matter) content by maintaining living plant cover and rooting whenever possible (integrate catch, cover and companion crops) and limiting cultivations. Organic matter also ‘feeds’ soil biology, key to improving aggregate stability and nutrient cycling
• Boost crop rooting to allow plants to access water stored deeper in the profile – phosphorus is key to root development
• Remove barriers to rooting, such as compaction or tight layers – avoid repeated cultivations to the same depth year after year. Target cultivations to specific issues where necessary.

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