Sludge in balance
Sludge in balance
MAKE sure your nutrient balances dont get out of kilter if you are planning to use sewage sludge. That is the warning from the Potash Development Associations John Hollies now the ban on dumping at sea is in force.
Correctly applied sludge can be a valuable source of nitrogen, phosphate and trace elements as well as organic matter. But it contains little or no potash, Mr Hollies reminds growers.
The biosolid nutrients will boost growth, but can soon exhaust potash reserves, especially on light soils, he explains.
"Nitrogen and potash are essential partners." If potash is limited, the crop will not respond fully to nitrogen. This cuts yield and risks nitrate leaching, he says.
A new free PDA leaflet Potash & Biosolids gives typical nutrient contents of biosolids, outlines the sludge regulations and offers guidance on potash needs and timings for all main crops and grass.