Watch your P's & K's for cereals

Cost saving pressures

There is tremendous pressure on cereal farmers to reduce costs. Around a third of total cereal variable costs goes on fertiliser and many farmers are reacting by reducing P and K usage. For the UK as a whole, less potash has been applied to cereal crops than has been removed in each of the last 8-9 years. Such trends are clearly depleting soil reserves and run the risk of reduced yields and grain quality. In these cases crop value losses will far outweigh the cost savings. 40% of the winter cereal crops nationally are estimated to have received no P or K at all in 2002/03, despite only 25% of soils being at a fertility level that requires no potash. These trends represent a ticking time bomb for cereal farmers now on inadequate soil reserves.

Don't be fooled by appearances

It is tempting to believe that crops are performing well if there are no signs of deficiency. Yield losses often occur with no visual symptoms - potash deficiency is described as 'hidden hunger' for this reason. It is also difficult to judge visually if crops have achieved their full potential within the limits of the climate and conditions of the particular year, or whether lack of inputs has limited yield. Nutrient symptoms may appear but be difficult to diagnose because of many possible causes, or appear too late to remedy and avoid crop loss. Crop appearance cannot therefore be relied upon to identify P and K shortage - soil analysis must be used to determine the need for fertiliser and the opportunities for cost saving.