9 June 1995

Fertiliser boosted by organic extra

ORGANIC-BASED fertilisers could help arable growers achieve higher yields from a more environmentally friendly fertiliser.

That is the claim for the HumberPalmers range from Sheppy Fertilisers. So far its main use has been for grassland (see livestock) and high value niche crops. But trials are planned for cereals and potatoes this autumn.

The organic-based, granular compound fertiliser contains conventional mineral nutrients – ammonium sulphate, potassium chloride and single super phosphate – plus a "secret" organic constituent.

That vegetable-based element ensures phased release of the nutrients, explains Sheppy chairman David Stevens.

Pot trials with Italian ryegrass in Belgium show an increase in yields of at least 35% over conventional fertiliser treatments. The uptake of nutrients is also improved – 85% of nitrogen compared with 55% usually, phosphate uptake 23% higher and potassium 30% higher – making for a more environmentally friendly product, the company claims.

Some arable farmers already use HumberPalmers. But to tailor nutrient availability to arable crop demands more precisely, five new organic bases are being evaluated to see if they offer more suitable release characteristics, says Mr Stevens.

If extra N is needed for specific purposes, such as to boost protein content in cereals, ammonium nitrate treatments could still be used, he adds.

Excessive N avoided

Despite the greater uptake of N, excessive nitrogen contents are avoided in vegetable crops by the higher yields. This is being investigated in lettuce and spinach where a 26% yield boost has been seen. "If the N levels are as low as we think, we will be talking to the supermarkets. But we need results first," says marketing director Alan Moon.

Although the nutrient analysis of most HumberPalmers fertilisers is lower than most inorganic fertilisers, and the cost higher, at £148-£162/t, the cost benefit relationship still works, says David Stevens. "Their sulphur content alone can justify the cost in some cases."

Charles Abel