Application of phosphate in spring is essential for good grass growth and improved yields. Phosphate accelerates grass growth due to its association with energy transfer within the plant and root development.
Specific application of phosphate in early spring has been shown to increase grass yields, even in soils with adequate reserves. However, soil testing should still be used to establish the quantities required, especially as it has been shown that 34% of soils are phosphate deficient.
It is important to remember that in even though soils may have adequate phosphate reserves, this may not be readily available for the crop. This means that in the cold and wet conditions associated with early spring, much of the soil’s phosphate reserves are not available for uptake by the crop.
In addition, phosphate can become ‘fixed’ in the soil. This happens as soluble phosphate has a negative charge, and so forms strong bonds with positively charged cations such as iron and aluminium in acidic soils, and calcium and magnesium in alkaline soils.
In certain cases, the fixation rate can be high, with up to 75% being fixed within four to six weeks.
Considering all of this, it is important to remember that in April and May the uptake of phosphate can increase 0.6 kg per day, and at this uptake rate soil reserves are not adequate. Therefore, applying phosphate during early spring will help to ensure good growth and improved yields.
The type of phosphate applied should also be considered, Gafsa, for example, is a reactive rock phosphate which results in a sustained steady release of phosphate which is less soluble and is less liable to being fixed in the soil. This makes it an ideal phosphate to apply during spring to promote good grass growth.
For more details please contact your local Account Manager or contact our Forage Team here.
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