29 December 1995

ADAS samples show higher soil N levels

NITROGEN residues in soils are much higher than normal. But it is too soon to say what adjustments to spring fertiliser dressings may be needed, claims ADAS.

Samples from 28 sites across the country show N levels well up on the past two years (see table). The dry summer, lower uptake by some crops and warm, wet soils favouring mineralisation are all responsible.

Many soils are still very dry, so leaching levels have been low. But forward crops will contain more N than usual, which is now "relatively safe" from leaching. A wet winter could still increase the risk of leaching. But if residues remain high a good slug of N will be available for crops come the spring. Where they are "significantly higher than normal", rate cuts may be justified in some circumstances, says ADAS.

Further soil checks in January and February and rainfall data will be used to offer guidance for 1996. &#42

Average nitrogen supply (soil and crops) according to ADAS (kg/ha)

After After

cereal oilseed rape

(all soil types) (all soil types)

Autumn 9580121

Autumn 945883

Autumn 936689