Effects of herbicide and nitrogen fertilizer application on grain yield and quality of wheat and barley

Field trials in commercial cereal crops were carried out over three growing seasons between 1988 and 1991 on farmland near Basingstoke, Hampshire to monitor the effects of reduced agrochemical use on crop quality. The lack of highly competitive weeds on the study sites gave little benefit in yield from the use of herbicide. In some cases no weed control or half rate applications gave significantly better yields than the full recommended rate. Herbicide applied at the full recommended rate significantly increased grain N in two of the experiments, despite no notable yield benefit from weed control. Grain N was the only aspect of grain quality to show a consistent decline with even moderate reductions in N application rate.