Effect of sulphur fertilization on grain yield and yield components of winter wheat

The effect of sulphur application on winter wheat yield and yield components on two different soils in northern Estonia and southern Estonia during 2004–2009 was investigated. Sulphur was applied with NS-fertilizer Axan or Axan Super at the rate of S 10 or 13.6 kg ha−1 accompanied with nitrogen background of N 100 kg ha−1, which effect was compared to effect of ammonium nitrate at the same rate of N. The rates of fertilizers were divided into two portions and applied at the growth stages 21–22 and 25–30. The effect of sulphur fertilization on the formation of wheat yield varied on a quite large scale depending on soil and weather conditions of trial locations. The yield components were closely related: when one component was changed, the other components sometimes compensated for grain yield. Sulphur deficiency symptoms appeared on the break-stony soil at Saku in a somewhat stronger form than on the pseudopodzolic soil at Auksi. The results of field trials conducted at Saku during the four years can be summarized as follows: the application of sulphur increased the number of ears per unit area by an average of 14.0% and the number of grains per ear by an average of 18.6%. At the same time, sulphur decreased the 1000-grain weight. As a final result, sulphur application on break-stony soil increased the wheat yield by 1.16 t ha−1 on average, i.e. by 23.0%. Sulphur application in trials conducted on pseudopodzolic soil at Auksi during years with different weather conditions in growing season proved highly effective in three of five trials. As an average of all trials in Auksi, the sulphur application increased the number of ears per unit area and the number of grains per ear by 23.9% and 7.7%, respectively. The grain yield increased under the influence of sulphur on the average of all trials conducted on pseudopodzolic soil by 1.25 t ha−1, i.e. by 22.4%.