Sulphur is an essential nutrient for all crops – the uptake of Sulphur in crops is about the same as that in Phosphate. Although the soil can supply some Sulphur – typically 7-12 units a year – the main source of Sulphur for crops has been atmospheric pollution. Recent improvements in pollution control and changes in the type of fuel that is used have greatly reduced this source of Sulphur. Yield responses to applied Sulphur are now widespread and large, and can be found almost everywhere in the UK outside the industrial Midlands.

In a series of 23 field trials on a grass cut for silage, Adas found an average increase of 9%, nearly half a ton of dry matter per acre. Individual trials showed yield benefits of up to 47%. Other organisations have found similar results on yield responses are now being reported in oilseed rape and cereals in the main arable areas.

Sulphur is taken up by the roots of the crop. Sprays therefore are only effective as Sulphur sources once the Sulphur has been washed off the leaves into the soil. The Sulphur in Amsul is applied directly to the soil and is immediately soluble and available to the crop. Amsul is simply the best fertiliser for applying Sulphur to crops.

Application Recommendations

In areas where sulphur deficiencies occur or are expected – and these now include a large part of the UK – Amsul is the best source of fertiliser Sulphur. At just 1 or 1.5 bags per acre, Amsul will provide adequate Sulphur for all crops, together with part of the nitrogen requirement. Amsul should be applied in Spring to arable crops, for example, as the early dressing on cereals or oilseed rape. On grassland, Amsul can be applied in Spring for first cut or mid-season for grazing.

Nitrogen

The nitrogen in Amsul is all in the ammonium form. Once applied to the soil this ammonium – N will be used by the crop or converted to nitrate – N which is also taken up. Under most circumstances, the effectiveness of Amsul as a nitrogen source is the same as that on ammonium nitrate.

Amsul can be more effective than ammonium nitrate when the soil is cool and wet as in early Spring. Under these conditions, nitrate-N can be lost by leaching or conversion to nitrogen gas. The same conditions prevent or slow down the conversion of ammonium-N in Amsul (which is not lost but can be taken up by crops) to nitrate-N. In these circumstances therefore, Amsul is a preferable nitrogen source.

This is shown by trials carried out on grassland by the Agricultural Research Council (the Grassland Research Institute annual report 1982 pages 26-28).

Losses of nitrogen where Amsul was used was between 1/5^th and 1/20^th of those found with ammonium nitrate. As a result, yields were more than 25% higher where Amsul was used.

Application Recommendations

Amsul has long been used as a nitrogen fertiliser, is suitable as a top dressing for grassland and all arable crops and can be substituted for ammonium nitrate on a unit of N. basis. Because Amsul contains 21%N, 1.5 bags of Amsul can replace 1 bag of ammonium nitrate. This simple rule covers the use of Amsul in almost all circumstances.

As with any fertiliser nutrient, care should be taken not to over supply sulphur. Excess Sulphur on oilseed rape has been shown to slightly increase glucosinolate levels – and on grassland where there is a risk of copper deficiency this can be exagerated by excess sulphur.

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