Experiments were carried out in 1985 and 1986 on a sandy clay–loam to investigate the effects of above average rainfall in May and early June on the growth of the spring barley cv. Klaxon in three systems of cultivation. The cultivation treatments, ploughing (P), shallow-tine cultivation (S) and direct drilling (D), had been repeated on the same plots and cropped with spring barley each year since 1971.
A total of 112 mm water was applied to the waterlogged subplots in 1985 and 168 mm in 1986.
Compared with plots receiving the normal seasonal rainfall, extra water had no effect on shoot or grain yield in 1985 (mean grain yield 6·38 t/ha) and there were no significant differences between cultivation systems. In 1986, in contrast, water, in excess of normal rainfall, depressed both shoot growth and grain yield (mean grain yields 4·49 and 4·07 t/ha for the normal rainfall and the additional water treatments, respectively), the effect being greater on P than on either S or D.
In both years, saturation was achieved in the topsoil for a prolonged period during May and early June in the waterlogged subplots. In 1985 this was associated with a period of low oxygen flux and low redox potential, but this did nothave a significant effect on root or shoot growth. In 1986 there was no comparable period of reduced aeration, nor any significant differences in oxygen flux or redox potentials between water and cultivation treatments. In 1986, reduced growth and yield were directly associated with a mean reduction in N recovery by shoots of 36 kg N/ha, the effect being greatest on the ploughed plots where water was added. The results do not support the hypothesis that waterlogging per seaffects the growth of barley more on ploughed than on direct-drilled land.