Potash Effect on Straw Strength

August 2023

With cereal harvests finished, or drawing to a close for another year, consideration should be given to the input decisions made during the year before it is too far in the memory and blurs into all the rest!

2023 has been another challenging year, for different reasons (again!). One noticeable difference this year was the number of crops that lodged due to the heavy rains and strong winds in early summer. Whilst PGR programs may be scrutinised and agronomists challenged, it is worth considering all the factors that can affect straw strength and crop’s standing ability, including disease and crop nutrition. In relation to nutrition, potash enhances the development of strong cell walls and therefore stiffer straw. Lodging is affected by obvious factors such as variety, nitrogen rate and weather, but low potash levels also increase the risk of lodged crops with the associated loss of yield and quality. The effect can be as dramatic as a lack of growth regulator in some circumstances, as illustrated in the photograph below.

Potash is clearly not the only factor affecting straw strength and lodging risk, and as already mentioned the weather was particularly suited to lodging this year; but considering this follows a period of high potash prices and a succession of years of reduced potash applications, not to mention increased offtakes following last year’s high yields, it could be worth giving this input an extra thought this autumn.