Abstract
SUMMARY The median concentration of phosphorus and potassium in a total of 867 samples of wheat and barley straw at harvest in England in 1986–88 was 0·07% P and 1·00% K in the dry matter. Variation was significant between years and between crop species. The concentration of potassium in wheat and barley straw increased with increasing rate of applied nitrogen at 60% of the sites where this was tested. The results have been incorporated into practical recommendation systems for farmers.