Winter cover crops provide important ecological functions that include
nutrient cycling and soil cover. Although cover crop benefits to
agroecosystems are well documented, cover crop use in agronomic farming
systems remains low. Winter cover crops are usually planted in the fall
after cash crop harvest and killed the following spring before planting the
next cash crop. Recent research has identified time and money as major
impediments to farmer adoption of winter cover crops. Developing innovative
cover crop management systems could increase the use of winter cover crops.
A scientist with the USDA Agricultural Research Service National Soil
Tilth Lab and colleagues at Iowa State University investigated the potential
for winter cereal cover crops to perpetuate themselves through self-seeding,
thereby eliminating the cost of planting a cover crop each fall and time
constraints between cash crop harvest and the onset of winter. Results from
the study were published in the March-April 2008 issue of Agronomy Journal.

In the research investigation, winter rye, triticale, and wheat were
planted and managed chemically and mechanically in varying configurations to
facilitate self-seeding. After soybean harvest in the fall of 2004 and 2005,
establishment and green ground cover of self-seeded winter cover crops was
measured because of their important relationships with nutrient uptake
capacity and soil erosion protection. The study revealed that plant
establishment through self-seeding was generally accomplished within one
week after soybean harvest. Green ground cover and self-seeding was
consistently higher with wheat.

?The significance of this research, in addition to lowering the cost
and risk of establishing cover crops, is to extend the ecological functions
that cover crops perform beyond the normal cover crop termination dates
between mid-April and early May,? says Dr. Jeremy Singer of the National
Soil Tilth Lab. ?Furthermore, producers using organic crop production
techniques could adopt these systems because of the potential for enhanced
weed suppression without soil disturbance.?

According to Singer, increasing the presence of cover crops on the
landscape can increase nutrient capture and lower soil erosion, both of
which can improve water quality.

Research is ongoing at the National Soil Tilth Lab to identify
self-seeded cover crop systems that minimize competition with cash crops and
maximize the effectiveness of self-propagation. The impacts of cover crops
on soil quality in systems with biomass removal are also being investigated
because cover crops can help offset the carbon and nutrient losses that
occur when biomass is harvested in row crop production systems.

The full article is available for no charge for 30 days following the
date of this summary. View the abstract at agron.scijournals.org

Agronomy Journal is a peer-reviewed, international journal of agronomy
published six times a year by the American Society of Agronomy.

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