Plan a micronutrient strategy
for Maize, Soya bean crops
By Jim Ruen
A
nything less than a well-managed
production system is not going to accrue
full benefits.
Are your crops getting the micronutrients
they need when they need them? It may
be on overdue task to pay more attention
to micronutrient availability – if you plan to
manage the high-yield details.
"Increased yield levels are resulting in higher
nutrient removal rate in the grain. In particular,
where there is no regular history of manure
application, we need to pay more attention to
the soil's capacity to meet nutrient removal
needs," says Tony Vyn, co-author of a recent
study and professor of agronomy, Purdue
University, Indiana, USA.
Just as high-yielding hybrids take up
more nitrogen, they also take up more
micronutrients such as zinc, iron, manganese
and copper. Vyn suggests that micronutrients
could be a yield-limiting factor under highpotential environments. Although many soils
have supported crops without any signs of
nutrient deficiencies in over a century, bigger
plants and more grain harvested mean more
micronutrients exported, eventually leading
to depletion and deficiency. Sometimes
contaminants in lime or macro-nutrient
fertilizers applications, or even mineral
weathering, can help restore some soil
micronutrient concentrations. Knowing the
soil test levels for essential micronutrients is a
place to start the diagnosis.
Soil-root interface
Even micronutrient sufficient soils may not
be enough. Co-author Ignacio Ciampitti,
assistant professor of agronomy, Kansas
State University, USA, points out that nutrient
availability is more complex than simple soil
nutrient concentrations. "Nutrient availability
is also related to the plant's ability to take up
each nutrient at the soil-root interface," he
says. "Root system health and soil structure
are key factors in micronutrient availability. As
root surface area expands, it is quite possible
that lower soil micronutrient concentrations
are needed to adequately support uptake
requirements. More investigations are needed
in order to confirm this pattern."
Achieving an ideal soil-root interface depends
on having soil conditions that make soil-bound
micronutrients soluble to plants. "Multiple
factors come into play, including how good
the entire production management system is,
34 FARMERS GAZETTE
November 2015