How you handle soil fertility this year may help determine how many bushels of corn and soybeans you produce, and how much profit is left at the end of the season. Most agronomists say good crops start with the basics, including getting soil fertility right.
Nothing is more basic than regular soil testing, and applying lime and fertilizer where needed. Yet one Indiana ag industry expert recently estimated that 25% or more of Indiana farmland still isn’t soil sampled.
Steve Long’s fields are in the 75% that are sampled regularly. He doesn’t want to be shooting in the dark, guessing at what is needed. “We hire a local consulting service to sample our fields on a regular rotation,” says Long, Franklin, Ind. “We have our own spreader, and we can spread two products by variable rate, so we try to apply what’s needed on each field.”
Start with lime
Some might argue that liming to get pH right is as basic to soil fertility as soil sampling. Other nutrients are more effective when pH levels are in correct ranges. A chart printed in the Purdue University Corn and Soybean Field Guide clarifies how different nutrients are either more or less available to plants at different pH levels. Find “Availability of Elements to Plants at Different pH Levels for Mineral Soils” on Page 180 of the 2020 Purdue guide.
Long spreads lime with a pull-behind spreader consisting of a New Leader bed on a Waitt Industries chassis.
“It does a great job of spreading lime, and it’s set up so that we can vary the rate across the field,” he says. “We prepare a prescription based on what soil tests say, and then spread each field accordingly.”
Long has access to two relatively close sources of lime. The lime from one quarry is lower in magnesium than the other. “Since we are generally worried about having too much magnesium on our soils, we opt for the source lower in magnesium,” he says. “It’s a finely ground lime, which spreads evenly with our spreader.”
Several years ago, Long applied lots of gypsum. Since utility companies were required to reduce emissions into the atmosphere, gypsum is no longer as readily available in his area.
“It worked well for us, and we could spread it evenly with our spreader,” Long says. “We were also getting sulfur from it.”
Now that far less sulfur comes into the atmosphere from utility smokestacks, Long also pays attention to sulfur in his crop fertility program. Corn and soybeans once got all they needed for free from the air, but not anymore.
“We did custom spreading of gypsum and lime for a while,” Long says. “We’ve added acres over time and don’t do much custom spreading today.
“The other factor is that after several years of spreading, both for ourselves and other people, many fields are up to par on pH. In most cases, now it’s a matter of spreading smaller amounts at a time when soil tests show that it’s needed.”
That’s where the ability to vary the rate for lime really pays off, Long contends, adding, “When it’s time to spread lime on a field, some areas may only need a ton per acre, a few may need a couple tons, and some spots may not need any lime.”