THE WA No-Tillage Farmers Association is attempting to unravel the mystery of cation exchange capacity (CEC) in WA soils at its Meckering trial site.
CEC is a relatively new concept of soil fertility to Australian farmers. WANTFA has two CEC trials where soil calcium to magnesium ratios of 1:1 to 15:1 are being investigated to find the optimum ratio for cropping WA soils.
Now in its third year, the two CEC trials using Calingiri wheat sown at 80kg/ha on May 9, have successfully and evenly emerged, suggesting this year could yield useful results.
CEC is a measure of the interaction of clay in the soil and the electricity linked with nutrition.
Clay particles, or soil colloids, which can't be broken down any further or seen with the naked eye, have a negative charge.
Therefore fertilisers must have a positive charge to be held to the soil colloid.
However, the anions ‹ nitrogen, phosphorous and suphur ‹ are negatively charged and do not hold to the clay colloid.
Elements with a positive charge are called cations, which include calcium, magnesium, sodium and hydrogen.
According to soil fertility experts, optimum soil fertility can be obtained by balancing these elements whose availability in the soil is determined by their interaction with one another.
The WANTFA trials are attempting to discover the correct ratio to balance soil nutrients ‹ the optimum cation exchange capacity.
In the trials WANTFA is testing US farmer and farm consultant Neil Kinsey's theory that the optimum calcium to magnesium ratio is 6:1.
WANTFA expects more results to be available at its September 18 Meckering field day.