Mt Pleasant News

Wash Journal   Fairfield Ledger
Neighbors Growing Together | Aug 21, 2018

Black dirt is disappearing, expert says

Nov 24, 2017

By Brooks Taylor, Mt. Pleasant News


Remember those drives through the Iowa countywide several decades ago? Black dirt dominated what just a few months ago were fields of corn and soybeans.

Turn the calendar to today and fields of plowed black dirt are disappearing.

“If you go back 40 years ago, you are going to see a black surface on row-crop fields this time of the year,” recalled Virgil Schmitt, an agronomist and Iowa State University regional crop specialist. “Then farmers went to the chisel plow and various types of tillage.

“In the 1970s, farmers began leaving some crop residue on the surface,” he continued. “Today, not only is crop residue left on the surface, but a growing number of farmers are planting cover crops after harvest.”

The purpose of crop residue left on the fields, Schmitt said, is to stop land erosion and also hold nutrients in the soil. He said flat ground fares better than sloped ground after a heavy rain. “If you look at a flat piece of black ground, there won’t be as much erosion after a heavy rain as there will be on sloped ground.

A significant push for farmers to step up their erosion-prevention practices was included in the 1985 farm bill. Farmers had to take steps to curb erosion if they hoped to continue receiving federal subsidies and aid.

Cover crops, such as rye and turnips, are “growing very extensively,” Schmitt stated. He said the number of farmers planting cover crops still is small in the overall picture but has been aided by some cost-sharing funds through the federal and state government.

Rye, currently, is the most popular cover crop, Schmitt said. “Most farmers are planting rye because it is a ‘bulletproof’ crop and is the cheapest.” Rye costs approximately $35 an acre.

Schmitt said cover crops accomplish two purposes. “They provide a cover for soil, which minimizes erosions. They also hold phosphorous in place and soak up extra nitrogen.”

Although fields may seem dormant in the winter, Schmitt said bacteria in the soil is breaking down and releasing nitrogen, which if not held in place, runs off to nearby rivers and streams. “Cover crops are the only thing that stops phosphorous and nitrogen runoff,” the crop specialist remarked. “Farmers are afraid that if they don’t stop the runoff, the federal government is going to mandate practices to stop it. Farmers don’t want some guy in a three-piece suit, sitting behind a desk in Washington, D.C., telling them how to run their farm.”

The only thing stopping more farmers from planting cover crops is that they see it as a cost without an immediate benefit.

While there may not be an immediate benefit from cover crops, Schmitt said data shows that in 20 years, the fields will greatly benefit from cover crops.

In addition to adopting erosion-reducing practices, Schmitt said that farmers are making fewer secondary passes over the fields during fall and spring fieldwork. “Nature as well as routine traffic is providing nutrients, so not as much tillage is needed.”

Looking back 40 years, Schmitt said “today’s ground is much better taken care of due to better pest management, genetics, equipment and technology.”

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