Building soils for better crops
Cronin Farms, Gettysburg, S.D., is making some big gains in soil organic matter. It’s risen from 2% soil organic matter to 4% organic matter in recent years — which is worth about $1,100 per acre by some estimates.
“We saw a small, slow increase in organic matter after we converted to 100% no-till 20 years ago,” says Dan Forgey, Cronin Farms agronomy manager. But the gain was limited to the top few inches of soil where crop residue was concentrated.
• South Dakota farm sees a jump in organic matter over the past six years.
• The increase came by adding cover crops to the farm’s rotation.
• The practice increased nutrients and soil moisture.
The latest increase — about 2 percentage points — has come over the past six years since Cronin Farms began including cover crops in the rotation after spring and winter wheat.
“We used to think you wanted to keep stubble clean after harvest to conserve moisture,” Forgey says. “But we have learned the soil likes living roots more.” He says the soil contains microbes and other organisms that thrive on live roots. “They need to be fed just like us.”
Adding cover crops after winter and spring wheat keeps a living crop on the land throughout the growing season. Cover crops haven’t hurt Cronin Farms yields, even in dry years, because the crops have increased soil organic matter.
“Organic matter acts like a sponge,” Forgey says. “It will hold up to 90% of its weight in water.”In dry years, the added capacity makes a difference in yields. “When you have reduced yields in a dry year, maybe you have to start looking at soil health,” Forgey says.
Cronin Farms has about 8,500 acres of farmland and usually plants about 700 acres of cover crops each year. Legumes add nitrogen to the soil, and grasses add organic carbon and recycle phosphorus to legume crops. Oilseed radish is planted to loosen the soil and recycle N.
“We’re still learning about cover crops,” Forgey says. “But it’s clear. They are really accelerating the increase in our soil organic matter.”
TAKING STOCK: Dan Forgey probes a field planted to a cover-crop cocktail. He’s seeing an improvement in soil quality.
This article published in the April, 2011 edition of DAKOTA FARMER.
All rights reserved. Copyright Farm Progress Cos. 2011.