Results from Wheat Demonstration Plots

Background

Crops of wheat were grown on small unreplicated plots in the Arable Area of the National Agricultural Centre, Stoneleigh. The same treatments were used on the same plots for each of the 4 years; 1987-1990. Soil was sampled in the autumn before the first harvest year and in each autumn of the comparison.

The soil is a light sandy loam with an available soil K level of 93 mg/l (index 1) at the start of the work. This K status is typical of over one third of soils in the UK.

Whilst the plots were not replicated the general conclusions from this work are clear and confirm results from fully replicated scientific experiments elsewhere.

It was not the purpose of this work to determine the optimum rate of potash to use on this site but merely to demonstrate the effect of different levels of potash fertiliser on grain yield and quality and soil fertility.

Treatments

Three potash treatments were applied to the same plots in 1987, 1988, 1989 and 1990:

K0

nil

K1

70 kg K2O/ha

K2

140 kg K2O/ha

All other inputs were identical for all three plots

Visual differences

No detectable visual differences in growth habit or leaf symptoms were seen in the first two years. The summer of the third year (1989) was notable for extreme drought and high temperatures and the visual differences between the K0 plot and the plots receiving potash were quite dramatic from June onwards with premature ripening. The 1990 season was also dry with quite high temperatures and the K0 plot was evident at an early stage with patchy stunted plants which failed to develop and showed marked yellowing of leaf margins and tip with early death of older leaves. By June, the K0 plot would have been described as a crop failure with premature senescence and this was reflected in yield. Little visual difference existed between the K1 and K2 plots both carrying what looked like a "reasonable" crop.