3 November 1995

Copper can be depressed by manganese

APPLYING manganese in sulphate and inorganic forms can depress copper levels in plant tissues. As a result crop growth, seed set and disease resistance can all suffer, claims Stoller.

The antagonism was demonstrated in SAC trials on a site known to be deficient in manganese, the company says. A manganese sulphate supplement was compared with Stollers Key Feeds chelated manganese.

Most vigorous

Both treatments cured the deficiency, but the sulphate product pushed tissue copper below the 4ppm critical level. Trial notes show the plots treated with Key Feeds were most vigorous.

"This is a clear indication that balanced nutrition can help plants withstand the stresses of the growing season. Unfortunately, many farmers are led to believe that high manganese concentrations in plant tissue is the main objective," comments Stoller managing director Jim Verner.