Posted 29 April 2014. PMN Crop News.
A New Twist on Buffer Strips in the Southern Great Plains
Source: American Society of Agronomy Press Release. www.agronomy.org
Madison, Wisconsin (April 3, 2014)--It can be tough being a crop in the Southern Great Plains. While irrigation has transformed the area into productive agricultural land, crops growing there still face obstacles. Low rainfall and humidity and high solar energy in the region leads to evaporation. Strong winds cause erosion and carry moisture away. As the Ogallala Aquifer, the source of much irrigation water, dries up, farmers and agronomists have to find ways to conserve water and protect their crops – and Sangamesh Angadi may have a solution.
Shelterbelts and buffer strips have often been used to block wind and reduce erosion. Angadi, an assistant professor at New Mexico State University, is adding a twist – he’s making them circular.
“The effectiveness of buffer strips is at a maximum when the wind direction is perpendicular to the strip,” he explains. “But wind direction can vary quite frequently. Circular buffer strips can reduce the wind effect from any direction.”
Blocking the wind’s effects can be extremely useful, especially when used with center pivot and partial pivot irrigation. With center pivot systems, farmers have the ability to irrigate an entire circle of crops. As water sources decline, however, many farmers have moved toward partial pivot irrigation, where only a portion of the circle is irrigated. The farmers plant traditional crops on the irrigated portion while leaving the rest of the circle fallow or planting crops that require less water.
Partial pivot systems can save irrigation water, but they can also create conditions that encourage evaporation. Because only part of the circle is irrigated in these systems, the other part will remain dry. Wind from those dry areas, then, can blow over the irrigated portions and take water from the crops. And the same thing can happen even when the full circle is irrigated if neighboring fields are drier.
“Each pivot or part of a pivot acts as an island of water vulnerable to evaporation,” says Angadi.
Multiple circular buffer strips arranged in concentric circles within the field could help protect those islands. The buffers, made up of grasses, would stop drying winds from reaching the soil surface and reduce the need for additional irrigation.
The use of circular buffer strips in partial pivot fields would take advantage of the part of the field that is left unirrigated. That under-utilized area could be redistributed into the concentric circles of the buffer strips. That way, Angadi says, the farmers would see minimal loss of crop area. In fact, with the many positive impacts expected from the circular buffer strips, total production of the main crop may even increase.
While Angadi is focusing on the water use benefits of the circular buffer strips, he anticipates several other benefits from what has been seen with linear buffer strips. In addition to reducing evaporation, blocking wind can help protect seedlings and improve the microclimate surrounding the crops. The buffers will provide a physical barrier to reduce soil erosion and runoff. And perennial grasses in the buffers can supply offseason forage, sequester carbon, and even provide habitat for wildlife and birds.
With all the potential of circular buffer strips, Angadi is now looking to further test his ideas and work with farmers to implement them. The ideal grass for the buffer strips still needs some investigation, and the choice will likely depend partly on the farmer.
“An ideal grass for the system should be taller growing, have offseason growth potential, be native or better adapted to the area, and have minimal input requirements,” explains Angadi. “The grass will also depend on the needs of the farmer. If the farmers wants to graze animals, forage quality should be considered.”
In addition to working with growers to find the best grasses for the circular buffer strips, Angadi will also consult with them to determine the best way to design and implement the strips. Many farmers in his area of the Southern Great Plains are already growing crops in circles making the adoption of circular buffer strips easier. But the best widths for both the buffer strips and the crops will need to be tested, and adjustments may have to be made to accommodate farm equipment, such as sprayers and combines.
Angadi recognizes the need for further study and planning, but he is excited about the potential of circular buffer strips. It seems as though farmers in his area are too. One farmer with whom has shared his ideas told him, “If you show significant benefits with circular buffer strips in the region, then I will figure out how to make the equipment work with them.”