Recent trials have proven that using a controlled release fertiliser (CRF), in place of a standard nitrogen programme, can significantly increase marketable potato yields by over 7t/ha, lifting gross margins by as much as £580t/ha.
These trial results have come at a key time, as Defra recently introduced a new set of ‘farming rules for water’ to help protect water quality. And the use of CRFs could help meet one of the key aims, of minimising nitrate leaching.
“The innovative CRF technology is simple but effective, the fertiliser granules are coated with a semi-permeable layer that acts like a gateway,” explains Dr Richard Collins, ICL technical sales manager.
“As the soil temperature increases, cracks open in line with the plant’s nutritional needs. But if the temperature drops, these close and reduce the nutrient flow to the crop, so that wastage is avoided, and leaching is greatly reduced.”
He goes on to explain that careful planning of fertiliser applications is also a requirement of the new farming rules.
“Using the right fertiliser blend for the field is key to productivity, and as stated in the rules, regular soil testing can help farmers to understand the specific crop requirements.
“While individual fields will have different needs, some potato crops will require a small amount of straight nitrogen just after emergence, in addition to the base applications, to give the crop a boost.
“After this, a CRF such as Agrocote, that offers a gradual ‘drip-feed’ of nitrogen is preferable throughout the growing season and can eliminate the need for follow up applications.
“Getting this balance right will ensure that nitrogen leaching is kept to a minimum. Too much fertiliser applied to a young crop will not only be lost from the soil, but it will also encourage inefficient and excessive leaf growth instead of tuber development,” explains Richard.
 Based on a price of £100/t for potatoes and a 7.5t/ha increase when using