Phosphate is essential for crop growth and development as it plays a major role in the energy behind many plant metabolic processes, enzyme activity and in root development. This energy is required for the active uptake of other nutrients and although its demand is small compared to nitrogen, its availability is essential. The irreplaceable role of P in plant nutrition requires that sufficient P is available in soil to meet the needs of the growing crop in order to produce optimum, economic yields. Phosphorus can limit crop yields on 30-40% of the worlds arable coils

The phosphate in Cropkare is more than 50% soluble in 2% citric acid and almost half is soluble in neutral ammonium citrate. This provides a phased release phosphate supplying the nutrient immediately and more long term to the growing crop. Therefore making Cropkare ideal for raising and maintaining the soil phosphate status.

The most marked effect of phosphorus deficiency is poor growth, normally associated early on before the roots have fully developed in arable crops. Plants may also suffer from a rigid erect appearance with slender stems. Leaf expansion and leaf surface area as well as the number of leaves per plant are decreased. Purpling around the edges of leaves is often seen in deficient plants, especially when temperatures are low. Other than stunted plants, phosphorus deficiencies can be difficult to visually diagnose in field, therefore it may be necessary to conduct soil and/or plant tissue analysis.

Most UK soils have adequate supplies due to years of applications, however this should not lead to complacency. The large yields now expected from today’s agriculture remove large amounts of nutrients from the soil, unless replaced soil reserves will start to deplete, for example silage can remove up to 2kg of phosphate per tonne of 20% DM silage. Limiting levels of phosphate can affect yields of grass and clover leys.

Plants are only able to take up phosphate from soil solution, however very little phosphate in the soil is held in this form. Phosphate uptake from the soil is highest during the spring, however only a fraction of the stable P will be released into the soil solution. Movement of phosphate from the stable pool to the soil solution can be adversely affected by:

Low phosphate concentration in the soil
Poor soil structure/compaction
Insufficient soil aeration
Very low or high soil pH*
Low temperatures
Wet/dry periods

* The availability of phosphate in Cropkare is not affected by soil pH