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. (1)

These trial results have come as Defra recently introduces a new set of ‘farming rules for water’ to help protect water quality. The use of CRFs could help meet one of the key aims, the minimisation of nitrate leaching.

Dr Richard Collins, ICL technical sales manager said: "The innovative CRF technology is simple but effective, the fertiliser granules are coated with a semi-permeable layer that acts like a gateway.

“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.”

Careful planning of fertiliser applications is also a requirement of the new farming rules.

Dr Collins said: “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 the use of a CRF that offers a gradual drip-feed of nitrogen can eliminate the need for follow up treatments.

He said: "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."

The new farming rules for water include:

1. Planning use of manures and fertilisers

2. Storing organic manures

3. Applying manures or fertilisers

4. Where not to apply organic manures

5. Where not to apply fertiliser

6. Reasonable precautions to prevent soil erosion

7. Protecting against soil erosion by livestock

8. Position of livestock feeders


(1) Based on a price of £100/t for potatoes and a 7.5t/ha increase when using