The current low prices of grain crops are adding to planting decision challenges in 2016.
"Reduced prices for corn, wheat, and soybeans, the three crops most commonly grown in South Dakota, will make it more important than ever for producers to use best management techniques to reduce risk and production costs," said Ruth Beck, SDSU Extension Agronomy Field Specialist.
Increasing diversity in the crop rotation is one tactic Beck encouraged growers to consider.
"Diversity can provide numerous benefits - and an easy way to incorporate diversity is by using rotations of both warm and cool season grass and broadleaf crop types."
Why diversity matters?
Over the last few decades, Beck said many South Dakota producers have reduced rotational diversity due to market and policy forces. "At the same time, the availability of technologically advanced inputs, such as glyphosate resistance crops, has mitigated the increased pest pressure that resulted from this approach," she explained. "Today, low commodity prices coupled with the development of pest biotypes resistant to many of the frequently used products makes staying the low-diversity course less attractive."
Especially troublesome are crop production practices that include only two species with the same life cycle such as both warm-season crops or both cool-season crops, explained Ruth Beck.
"One year away from a crop is often not enough of a break to reduce pest issues," she said.
Beck pointed to research conducted in South Dakota and Colorado by Dr. Randy Anderson, USDA Weed Ecologist, which has shown that if producers can rotate out of a crop or crop type (i.e. warm season vs. cool season) for periods of two or more growing seasons, pests that are inherent to those crops are significantly reduced as compared to fields where there is only one year between similar crops.
"For instance summer weeds that tend to germinate in late June and July are often more of a problem in crops like corn and soybeans. Growing small grains would extend the interval between corn crops and soybean crops," she said.
This could be seen as an integrated pest management tactic. Small grains would be much more competitive with summer weeds because by the time warm-season weed types germinate the small grain crop would be tall and leafy with an extended root system.
"This would enable it to outcompete the summer weeds for nutrients, water and light, often without the need for an herbicide treatment," she said.
Those summer weeds that do survive could be controlled as well with a wide variety of herbicide choices after the small grains harvest. Dr. Anderson concluded that utilizing diverse crop rotations, can substantially and naturally decrease problem weeds.
Similar benefits can be expected from rotations when considering other pests. "In fact some researchers attribute the synergism seen from crop rotation to be, in part, attributed to reduced levels of root diseases or other pests specific to a host crop," Emmanuel Byamukama, Assistant Professor & SDSU Extension Plant Pathologist said.
For instance fields growing corn on corn could have high levels of root and foliar pathogens specific to corn. A three or four year rotation out of corn would reduce those pathogens and other corn specific pests in that field to much lower levels.
Including a small grain in a rotation with corn and soybeans can also provide producers with a window to grow a cover crop.
"Cover crops have been shown to benefit agricultural soils by increasing soil biology, improving nutrient cycling, organic matter and water efficiency," Beck said. "Cover crops can also provide livestock producers with additional forage."
Another benefit of small grains is their high carbon content.
Beck explained that including another high carbon crop (in addition to corn) to a crop rotation will make the ratio of high carbon crops to low carbon crops 2/3's to 3/4's. "This can also improve water efficiency, soil structure and quality, and increase water holding capacity," Beck said.
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