OUR Soil Mineral Nitrogen (SMN) project in Devon’s Otter catchment has helped farmers save thousands of pounds while supporting river health.
The scheme falls under the Upstream Thinking 3 (UST3) programme, funded by South West Water (SWW), which works with farming communities across Devon and Cornwall to reduce the impact of farming practices on water quality.
Farm advisor for UST3 Yog Watkins said: “Our 2022 SMN project assisted several farmers in the Otter catchment in conducting analysis to support their on-farm efficiency, while also making good business sense.
“Following a review of their likely nitrogen application plans for the growing season and how much these had been adjusted due to cost, we shared the results of their SMN test to enable further application adjustments up or down.
“One of the larger farms has already tested all of its arable fields this year and adapted the application strategy to limit any environmental impact and save cash.”
More than 425 hectares of conventional and organic land has been tested, all within SWW public water supply safeguard zones, which are the most vulnerable to nitrogen losses and have the greatest bearing upon public water supply.
A total of 79 fields have been analysed of varying intensity: 50% arable, 33% grass and the remainder forage cropping (mostly maize), with data showing significant reductions in nitrogen applications, with the majority coming from the arable fields.
Total applications across all the fields fell from over 57,114kg Nitrogen (N) to 49,521kg N, with 2,632kg N of this due to the high price of N and 4,961kg N due to adjustments based upon the SMN results.
With Ammonium Nitrate fertiliser costing £841/tn (£2.44/kg N) in July 2022, the savings equated to over £18,500 with an average saving per field of £234.
Arable savings were considerably more at £340/field, £148/field for forage and £113 for grassland, with one field’s savings over £1,350.
A 7,593kg N reduction in application is the equivalent of 22tn of AN fertiliser.
The amounts saved are before sampling costs of £121.40 per field (which can be reduced further if carried out to a shallower depth).
Better financial gain for grassland may be possible if testing one field in a block of the same soil, topography and management as a bellwether to adapt N applications across the whole block.
Yog added: “These are unprecedented times in farming and costs are volatile, so it is good practice to monitor efficiency across farming systems.
“Through the project, we have learned targeting testing to the higher N application fields first will provide the biggest potential savings.
“Fine tuning nitrogen applications can save farmers significant money, while also avoiding fertiliser losses to the environment – it’s a classic win-win, as the farmers save and SWW save in water treatment costs which should result in lower water bills.”
Visit https://wrt.org.uk/project/upstream-thinking-3/ to find out about future opportunities to improve on-farm efficiencies and water quality.
You can read the article on the South West farmer website too: southwestfarmer.co.uk/news