Diagnosis of Sulphur Nutrition

Abstract

With decreasing atmospheric inputs (Daemmgen et al., 1997) and changes in fertiliser practices towards low or no sulphur (S) containing sources for nitrogen (N) and phosphorous (P) (Ceccotti et al., 1997), S has become a major limiting factor for plant production in industrialised as well as remote rural areas. But although today there are only a few places left where the average S input from atmospheric and fertiliser sources satisfies the demand of crops, not all sites with a negative S balance show S deficiency symptoms, and crop response to S fertilisation is not universal. This is because S is a geogenic abundant element (Clark, 1979) compared for instance to nitrogen, the origin of which in agro-ecosystems is predominantly anthropogenic. Vast amounts of S are bound in minerals (e.g. gypsum and pyrite) and delivered by ground water to the surface. For example some springs, like the Rhume spring in the German Harz mountain area in Northern-Germany (51.592°N; 10.304°E; WWW, 1997) delivers each year 7092 T of S bound to gypsum (Herrmann, 1969) which is twice the amount of S sold in the whole country as potassium-sulphate fertilisers and theoretically enough to fertilise 10% of all oilseed rape cropped in Germany with S. But also sites without access to mineral bound S sources may have sufficient S dissolved in soil water and shallow groundwater bodies available to plant roots (Eriksen et al., 1997, Bloem et al., 1997, Duynisveld et al., 1993). This is because soil water and shallow groundwater have much higher sulphate concentrations than water of precipitation which is due to natural S sources in the ground or due to the charging by atmospheric sources ( Eriksen et al., 1997).