Cover crops in rotation with cash and perennial crops have become an increasingly popular subject in North American agriculture, particularly as growers seek methods to reduce fertilizer inputs and combat soil erosion. Recent agronomic research supports the increased use of covers for both these reasons, and that should be a cue for equipment dealers to be on the forefront of educating their customers in the use of “year ’round green” schemes as well as providing them with the tools to do the job.
While roughly 20% of U.S. cropland is under no-till management, which provides a significant reduction in soil erosion and fertilizer losses due to physical soil movement, a 2017 study by the Department of Earth Sciences in the School of Sciences at Indiana University shows no-till by itself does not prevent nitrate leaching from farm fields as moisture moves down through the root zone of no-till crops. In fact, the study showed no-till fields were likely to increase nitrogen leaching over conventionally-farmed fields because of improved soil moisture infiltration.
Lixin Wang, an assistant professor and corresponding author of the study, says the findings show no-till needs to be complemented with other techniques, such as cover cropping and intercropping, or rotation with perennial crops, to improve nitrate retention and water quality benefits.
“We found the adoption of no-till results in increased nitrate loss through leaching due to macropores such as those created by dead roots and earthworm burrows in soils under long-range no-till management,” he explains.
Covers to the Rescue
In a 2015 study, researchers at the University of Illinois used a 50/50 mixture of oats and hairy vetch to test for potential reductions in nitrogen and phosphorus loss through tile drainage systems with the use of cover crops.
Results showed a 65% increase in cover crop growth was shown to significantly decrease nitrate leaching. The oat/hairy vetch cover crop had 12.7 times less nitrate leaching over the growing period compared with plots of bare soil in the experiment. Researchers explained the experiment represented the “worst-case” scenario by combining fall fertilizer applications with soil directly above a drainage tile, but a “best-case” scenario with a profile initially free of macropores.
In 2016, Iowa scientists conducted similar studies using a rye cover crop to determine its effect on corn production, nutrient leaching, drainage, soil moisture and temperature and spring nitrate tests. They found, while rye roots reduced available soil moisture by an average of 1 inch throughout the season, the roots have a greater potential to immobilize nitrates during decomposition than surface rye shoots.
Also, the Iowa study showed rye decreases nitrate losses by reducing nitrate-nitrogen concentration in drainage, rather than reducing drainage volume.
On average, the rye cover crop reduced nitrate losses by 26%, drainage by 4% and crop yields by 2%. Researchers explain the apparent yield drag could have been caused by lower crop population densities and other factors.
A Dealer Takeaway
The soil-health movement and economically-driven producer decisions to reduce inputs continue to heat up interest in the use of cover crops, even in semi-arid portions of the Great Plains. At the same time, farm program conservation funds are becoming more aligned to the adoption of cover crop establishment through adjustments to crop insurance regulations and relaxed program guidelines.
As growers continue to find ways to whittle inputs, cover crops wills become more valuable on larger numbers of farms. Because of this, equipment dealers have the opportunity to provide agronomic assistance or align themselves with crop consultants and organizations already providing technical help to growers interested in improving their soils and bottom lines.
Savvy sales managers will keep an eye on new planting technology aimed at cover crop establishment such as the latest in roller crimpers, sprayers and planter row-unit improvements. Similarly, as some growers move out of cost-share programs they used to establish cover crops between cash crops, some likely will see the economic benefits of adding or increasing livestock numbers to their operations to help improve nutrient cycling — and end of year profits.
Farm equipment dealers are standing in an enviable position at this unique time in U.S. farm history to provide services and sales to support this growing movement — a movement some have said represents, “The first time in recorded history we have to rebuild soils traditional farming practices have degraded over the years.”