Phosphate and potash use on UK crops has been falling for more than ten years. Since the mid-1990s, more phosphate and potash has been removed in the main arable crops every year than has been applied in fertilisers. Recent price increases are likely to make things worse and, if present trends continue, there will be a return to the serious phosphate and potash deficiencies in crops that were common in the past.

A recent summary by NRM of soil samples they had analysed showed 23% of arable and 30% of grassland samples had a P Index lower than target and 37% of arable and 43% of grassland samples had a K Index lower than target.

Good supplies of phosphate and potash are essential for the efficient use of nitrogen by crops and grass. Any deficiency can mean money wasted on nitrogen and greater risk of leaching of the nitrate that is not taken up.

Soil P and K Indices should be monitored by sampling every 3-5 years. Target soil Indices that will ensure full yield of crops or grass are 2 for P and 2- for K. If an Index falls below the target, yield will be at risk. Often, full yield can not be achieved at a low Index even where recommended amounts of phosphate or potash are applied. So, it is false economy to allow Indices to fall to 0 or 1 and then apply extra fertiliser to raise them – and it may take many years to increase an Index by 1 and in the meantime, profit will be lost.

Cropkare is a competitive and consistent source of phosphate, potash and other nutrients.

P Deficiency in Wheat  K Deficiency in Wheat
          P deficiency in wheat                       K deficiency in wheat