Despite making up only a small percentage of the soil — no more than 10%, according to the University of New Hampshire Cooperative Extension — organic matter plays a critical role in the soil’s health and the crops raised on it.
In a No-Till Farmer webinar, Doug Miller, agronomist and vice president of Erie, Ill.-based Midwest Bio-Tech, explained just why soil organic matter is so important, the factors that influence its formation and how no-tillers can help their levels climb higher.
One of the primary benefits of soil organic matter is its ability to hold onto nutrients.
Miller explains that 1% of organic matter contains about 1,000 pounds of nitrogen (N) per acre. However, only 2% of that N is converted by soil microbes to a plant-available form, which means only 20 pounds of N is available to the crop. So for a no-tiller with 3% organic matter, they can count on about 60 pounds of plant-available N, Miller says.
“People that have higher organic-matter soils can have almost enough N available to produce the next crop,” he says.
Miller notes that 95% of N in the soil is held by the organic matter, while 90% of sulfur and 40% of phosphorus come from it.
SMALL ROLE, BIG IMPACT. It may be the smallest component that makes up organic matter, but Doug Miller says microbes still play a crucial role. The vice president of Midwest Bio-Tech says they work to decay fresh residue, recycle nutrients to the next…