Increase ‘Available’ Phosphate Levels  download full pdf

Soil phosphate levels in the standard UK test may show a low level at index 0 or 1 in which case you may be recommended to apply phosphate fertiliser. Many people continue to apply phosphate but their soil levels remain low, so what is going on?

UK soils generally have good levels of phosphate in the ‘total’ bank, but availability may be a problem. The answer is NOT to apply more of something you already have plenty of, rather to make what you have more ‘available’. To do this we have to find out what is causing the ‘lock-up’. It could be one or more of the following:

  • Acid soil    (phosphate is most available st pH 6.4
  • Alkali soil  (phosphate is most available at pH 6.4)
  • Excess iron (or manganese) – usually a sign of low pH
  • Compacted – water-logged or very cold soil.
  • Lack of biology – low humus.

The key to improving ‘available’ levels of phosphate is to balance the soil as best you can; try to lift the calcium if this is too low, then feed the soil, get the essential phosphate-fixing organisms working for you. It is those tiny organisms that will pull the phosphate from the soil reserves and feed it to your crop.

In some instances, it might be necessary to apply these beneficial micro-organisms; we are now including them in the Better Grass Xtra product in the form of Mycorrhizal Fungi.

When you apply phosphate fertiliser it goes into the ‘available’ tank and is then moved to the labile pool and on to the reseerve tank. When crops gropw in the soil, they pull phosphate from the ‘available’ tank which is then replenished from the labile or reserve; sometimes you can have a blockage in the transfer mechanism – as described at the beginning of this note.

 phosphate reserves smaller

NB: Abridged version only, for full information please download pdf above