Know Your Soils

Knowledge of your soils will make you a better farmer.

Published on: Mar 21, 2011

Farmers may be the biggest challenge on their own farms, not for what they know, but for what they don't know about their soils, the man who hosts the AgPhD show on RFD-TV told a group of producers at the Mid-South Farm & Gin Show.

The difference between the majority of farmers and soybean yield champion Kip Cullers is their commitment to finding out how to raise better crops, says Brian Hefty, a South Dakota farmer who co-hosts the popular AgPhD program with his brother.

"Kip tells me that he gets up at 4:30 a.m. every day to read and learn about how to grow better crops," Hefty says. Cullers spends the off-season speaking at farm shows and talking with farmers trying to figure out how to raise a better crop. "Our own brain and work ethic is what makes us successful," Hefty says.

AgPhD: Brian Hefty, right, dispenses ag advice on the popular RFD-TV program.
AgPhD: Brian Hefty, right, dispenses ag advice on the popular RFD-TV program.

The starting point to better crops lies in the soil and knowing the holding capacity of that soil.

Soil testing is fine; knowing how to read a soil test is better.

The Cation Exchange Capacity tells you the holding capacity of your soil. It's one of the most important things about your soil, Hefty says. The soil contains three components that contribute to its holding capacity: Type of clay, amount of clay and organic matter.

A soil will hold approximately 10 times its CEC. "If you're raising 150 bushel corn, you need approximately 150 bushels of nitrogen. Whatever the soil's CEC, multiple that number by 10 to find its holding capacity.

And while you're doing that, consider the object lesson of putting the negative sides of a magnet together. They repel each other, of course. The same thing happens when you apply nitrates to the soil. Both nitrates and soil are negatively charged. So, you have to have a form of nitrogen that is positively charged in order to avoid leaching in the soil. "Ammonium nitrogen is a positive charge and holds the nutrients," Hefty says.

Do not over apply N in any form, including manure. If you're thinking about applying manure, have it tested. Split applications of N work well, a little in the fall, more at planting and the remainder at sidedressing, Hefty says.

In today's high-priced fertilizer costs, a nitrogen stabilizer is a good investment in order to keep nitrogen in its ammonium form. "Nitrogen stabilizers are more likely to pay for themselves when nitrogen prices are high," Hefty says.

In order to make nitrogen use more efficient, check sulfur levels in your soil. "You need a pound of sulfur for every 12 to 15 pounds of nitrogen," Hefty says. "200 hundred bushel corn needs 50 to 60 pounds of sulfur." Because air quality is cleaner than it used to be, there's less sulfur in the air, so less lands on crops.

Micronutrients are also super important for nitrogen efficiency. Potassium, zinc and boron are important. Use plant tissue analysis to increase yield.

"Learn how to read a soil test," Hefty says. "To be a better farmer and be a good steward of the soil and avoid regulations, get the most information you can about what your soils need."