Ploughing down v spreading fertiliser

08 June 1998

Ploughing down v spreading fertiliser

Question

DO we lose anything by ploughing down P and K fertiliser, rather than
spreading on to a prepared seedbed?

Response

John Williams, soil scientist, ADAS Boxworth, Cambs

Answer

THE short answer is no. But then you have to consider the soil indices for both
phosphorus and potassium and the depth of ploughing.

Most growers will have a soil analysis carried out every five years, or possibly three years in some cases. Most soils are soil index 2 or above for these. At index three we are talking about maintenance dressings only from time to time and I dont think it will make any difference at all how P and K are introduced. At index one, more regular applications are needed but, again, there should be little difference in application methods.

However, it is important to keep the nutrient level of the topsoil high, so
growers should not be ploughing too deeply in an index one situation. It is very
rare to get a response to P & K application because the aim is to supply a
maintenance dressing.

If it is a new field, if growers are not sure of the indices, then they do need
to get a soil analysis.