FORT WAYNE, Ind. — When it comes to soil nutrient
management, farmers must focus on not just the chemical side of soils, but the
physical and biological sides, as well.
Allowing proper aeration and water flow is critical for soil
health, said Joe Nester, agronomist and owner of Nester Ag Management. Gypsum, a
byproduct of the process used to clean the air in coal-powered power plants, can
help improve air and water movement through the soil.
Gypsum also affects the relationship between calcium and
magnesium in soils.
“You want to pay attention to the calcium level in your
soil,” Nester said. “There is a profound difference between calcium and
magnesium and the way they react to clay.
“Calcium looks very large compared to magnesium. Calcium can
flocculate, which means it puts particles together like a puzzle — the other
disperses clay. We have to manage the small-, large-particle
Gypsum helps move magnesium further down in the soil so that
it doesn’t disperse soil particles as badly, he said. Gypsum also causes an
average 55 percent reduction in phosphorus levels.
Adding this compound only works on clay soils, however. On
sandy soils gypsum is ineffective and farmers should look at sufficient levels
of available nutrients to determine what to add.
Nester discussed the results of a study done by the National
Soil Erosion Lab in 2002. It took place on a field with high magnesium levels
and non-tilled soils. Four separate plots were made, and fishbowls were placed
to collect runoff water from a rain simulator.
The plots that had gypsum applied to the surface had much
clearer runoff, while the other plots produced murky water. The dirty water was
holding important nutrients, Nester said, while the fields with gypsum retained
nutrients in the soil.
“Water infiltration is key,” the agronomist said.
Interested farmers with clay soils should speak with their
agronomist about gypsum. Nester said that typically one ton is applied per acre.
Gypsum is affordable because it is a byproduct from power
companies that need to get rid of the material.
“As land values, crop values, input costs and water quality
impact all increase, it becomes more important,” Nester said. “Soil, water and
air will have more impact on your yields than the nutrient levels you have.
“They work together, but the soil tests don’t show soil,
water and air. The grower that can manage soil structure and health with their
nutrients is going to make the most money. It’s all about minimizing stress and
the duration of that stress.”
There are several ways to succeed in farming today, he said.
Some farmers practice tilling, while others find no-till practices better. Both
methods have advantages and disadvantages that affect soil aeration and water
Tilling warms the soil, eliminates residue challenges,
distributes nutrients and leads to smoother soils. Although it temporarily
injects air, it decreases air flow in the long run, Nester said.
The disadvantages of tillage are that it disrupts soil
aggregates, making it hard for water to move up and down. It also decrease
carbon dioxide levels, disrupts earthworm and causes other damages.
Farmers must weigh the pros and cons to decide what
practices are best for their soils, Nester said.