Decision support for sulphur applications to cereals

Abstract

Yield response to the application of sulphur fertilisers has become more widespread in cereals. Without sulphur fertiliser, yield losses in winter wheat can be up to 30% in the most responsive situations (approximately £240/ha at current prices) but average 6% (approximately £48/ha). This represents a total potential loss of £83 million across England in winter wheat alone (with similar levels of yield loss in other cereals). On the other hand, a typical application of 20 kg S/ha costs about £10/ha, which would be a waste if crop yield does not respond to sulphur fertiliser. A number of factors interact to influence the soil sulphur supply and a crop's ability to explore the available sulphur pool in the soil. These factors need to be considered together to guide the decision on sulphur applications.

Two hundred and four field trials on sulphur responses in cereals were collated as part of the project. A subset of 88 trials with winter wheat was chosen for further statistical analysis, based on a number of selection criteria. Within this subset of trials, 26% showed a significant and positive response to sulphur application. The data were analysed to determine the key factors affecting yield response to sulphur.

Site factors including soil type and over-winter rainfall were found to be important, whereas the influence of sulphur deposition was relatively small. This is likely to be due to a combination of decreased overall sulphur deposition coupled with the relatively small range of deposition rates now experienced in rural areas of the UK. A new matrix scoring system was developed based on the relative contribution of over-winter rainfall, soil type and sulphur deposition to guide cereal growers on sulphur applications to cereals.