ISU Extension News

Extension Communications
Extension 4-H Youth Building
Ames, Iowa 50011-3630
(515) 294-9915

12/18/03

Contacts:
Mahdi Al-Kaisi, Agronomy, (515) 294-1923, malkaisi@iastate.edu
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033, jmcguire@iastate.edu

Consider Crop Rotation for 2004 Crop Season

AMES, IA --An Iowa State University (ISU) Extension agronomist suggests that farmers planning for the 2004 growing season need to consider the most effective crop rotation.

Mahdi Al-Kaisi, an ISU Extension soil specialist, said that a robust, multiple-crop rotation is one management tool that many farmers have largely overlooked in their search for a profitable and sustainable production system.

"A multiple-crop rotation system has many proven benefits over continuous cropping -- agronomic, economic and environmental," he said. "Farmers who use a multiple crop rotation can expect to improve yield and profitability over time; control weed, insect, and disease cycles; provide alternative sources of nitrogen; reduce soil erosion; increase soil organic matter; improve soil tilth, and reduce ag chemical contamination of surface water."

How does it all come together? Al-Kaisi said it starts with the improved soil structure that is a result of crop rotation. "Because the root systems of the plants in a rotation all differ, annual crop rotations create a variety of macro pores that influence soil environment. More macropores mean that soil infiltration is improved, nutrient pools are enhanced, and soil aeration is better developed, which, in turn, facilitates better environment for new root growth of successive crops."

Of course, the benefits of crop rotation have been objectively proven over time. Al-Kaisi cites a long-term study of crop rotation (conducted since 1876) done by the University of Illinois. "The evidence clearly shows that crop rotation is a winning management strategy," he said. In the study, continuous corn with no fertilizer decreased soil organic matter content by 45 percent in 55 years as compared to adjacent native grass. Such a removal of carbon from the soil leads to a decline in soil fertility and aggregate stability. And although the study seems dated, the principle demonstrated remains applicable today of long-term effect of cropping system on soil quality.

It is not an easy process to convert a farming operation into a multiple crop rotation, because with any new management system, there are going to be new concerns. Preventing herbicide carryover is critical. Introducing new crops also means acquiring new growing skills and using different equipment, perhaps even increased labor costs. Also, strategies need to be created for marketing multiple crops.

"But in the end, many Iowa farmers might find themselves surprised by the results of a cost\benefit analysis of crop rotation in their operation, Al-Kaisi said. "Building a sustainable and balanced system isn't easy. The key is to take the time to establish a set of clear objectives and understand the consequences -- pro and con -- of choosing a new management strategy."

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Funding support provided by USDA Natural Resource Conservation Service through Cooperative Agreement No. 74-6114-10-03.

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