Effects of timing of sulphur application on yield, S-uptake and quality of barley

Abstract

The effect of N application (four levels) and time of S application (from sowing to the middle of heading) on yield and quality of spring barley (Hordeum vulgare L.) was investigated in pot experiments. Also, a no S treatment was included. At the two lowest N levels grain yield was unaffected by S application, but with increasing N level there was an increasing yield response to S application. Deficiency symptoms were observed from the beginning of tillering onwards at the highest levels of N application. Sulphur applied when the flag leaf was first visible eliminated the symptoms and prevented yield reductions. Mineralised soil organic S fulfilled the S requirements of plants grown at the lowest N rate and sustained plants at the higher N levels until the late S application. The effectiveness of a late S application may be lower under field conditions because of poor mobility of S in the soil under dry conditions. Late S application caused the percentage of fertiliser-derived S in grain to decrease at all N levels. Without S application the concentrations of the S-containing amino acids cysteine and methionine decreased on both dry weight and protein basis, especially at the highest N levels. Late S application even at the middle of heading prevented this reduction of S-containing amino acids. This indicates that adequate protein quality may be achieved by delayed S application despite yield reductions.