Severn Trent Water’s 2,000-hectare biogas farm in Nottinghamshire has recently run trials undersowing maize with grass, with results showing a 50-tonne per hectare yield as well as improvements to soil health, nutrient management and water quality.
Farm manager, John Jackson, who has experimented with under-sowing throughout his 35-year career, explained that these results should counteract the scrutiny facing maize for its environmental impact.
“Under-sowing a fast-rooting Westerwold ryegrass mix has helped us create a stronger soil structure on our maize fields, minimising soil damage at harvest and improving nutrient management for the next crop – especially on lighter soils,” he said.
“We’ve seen reduced erosion in the trial plots, which also helps prevent run-off and nitrate leaching, therefore protecting local watercourses – with no penalty for maize yields.”
He added that the team committed to harvesting in September when the ground is more robust, so sowing should take place in April. “Whether you’re growing maize for grain, forage or biogas, as long as the soil temperature is reaching 8-10oC for four to five consecutive days and seedbed conditions are good, you can get drilling,” he explained.
“We drilled our maize in mid-April, with the ryegrass under-sown seven weeks later, in mid-July, when maize was at the 4-5 leaf stage and well-established.”
To minimise competition, he also recommends that grass is drilled into the maize crop, rather than being broadcast. “Ground contact is key – so the under-sowing was done at the same drilling width as the maize. If you go any wider, it results in drift – you need to ensure maize remains the main crop.”
Mr Jackson concluded that growers should aim to under-sow their next maize crop, as well as explore the funding options on offer to support the investment.
“For farmers in a priority Severn Trent catchment area, match-funding is available through STEPS (Severn Trent Environmental Protection Scheme). There are numerous options from under-sowing to cover crops and you’ll have access to a local agricultural adviser for support,” he said.
“Find the contact details for the adviser in your area on the Severn Trent website, along with details on options to support your business goals.”