USDA Natural Resources Conservation Service July 2015 Issue 15 - Herbicide Persistence and Rotation to Cover Crops – Barry Fisher, NRCS State Soil Health Specialist/Agronomist Victor Shelton, NRCS State Agronomist/Grazing Specialist Tony Bailey, NRCS State Conservation Agronomist This Crib Note is intented to supplement Indiana Agronomy Crib Note Issue 5, but should be useful for any summer or fall cover crop seeding. Heavy rains and major flooding have been common throughout Indiana this planting season. The full impact to agriculture is not yet clear, but we know farmers will need to manage and recover from the aftermath of rain and flooding now and in the future. When prolonged rain and flooding results in some fields that will go unplanted, or crop failure, farmers should still strive to accomplish something positive from the situation by planting cover crops. Farmers planting cover crops to regenerate soil health in these fields need to consider the potential for residual herbicides to affect the germination and growth of selected cover crops. Many fields intended for corn or soybean have already had one or more residual herbicides applied. Numerous factors affect the persistence (breakdown or half-life) of herbicides in the soil. These factors include but are not limited to: soil pH, soil organic matter, temperature, precipitation, exposure to sunlight, soil texture and biological activity. Additionally, understanding the differences in mode-of-action of each herbicide group is a great predictor of how tolorent a cover crop may be to each class of chemistry. Refer to the following link to a table compiled by Penn State Weed Scientists that helps predict which herbicides may reduce the success of cover crop establishment: There is also a table for the injury potential of some common herbicides (carryover risk) in the Midwest Cover Crop Field Guide: Also visit the Purdue Extension Weed Science page for additional information on herbicide mode-of-action at: Contact your local NRCS office for assistance in selecting cover crop plant species and seeding rates. Issues of this publication as well as additional NRCS Agronomy Resources are stored at:
USDA Natural Resources Conservation Service July 2015 – Issue 15 - Herbicide Persistence and Rotation to Cover Crops Barry Fisher, NRCS State Soil Health Specialist/Agronomist Victor Shelton, NRCS State Agronomist/Grazing Specialist Tony Bailey, NRCS State Conservation Agronomist This Crib Note is intented to supplement Indiana Agronomy Crib Note Issue 5, but should be useful for any summer or fall cover crop seeding. Heavy rains and major flooding have been common throughout Indiana this planting season. The full impact to agriculture is not yet clear, but we know farmers will need to manage and recover from the aftermath of rain and flooding now and in the future. When prolonged rain and flooding results in some fields that will go unplanted, or crop failure, farmers should still strive to accomplish something positive from the situation by planting cover crops. Farmers planting cover crops to regenerate soil health in these fields need to consider the potential for residual herbicides to affect the germination and growth of selected cover crops. Many fields intended for corn or soybean have already had one or more residual herbicides applied. Numerous factors affect the persistence (breakdown or half-life) of herbicides in the soil. These factors include but are not limited to: soil pH, soil organic matter, temperature, precipitation, exposure to sunlight, soil texture and biological activity. Additionally, understanding the differences in mode-of-action of each herbicide group is a great predictor of how tolorent a cover crop may be to each class of chemistry. Refer to the following link to a table compiled by Penn State Weed Scientists that helps predict which herbicides may reduce the success of cover crop establishment: There is also a table for the injury potential of some common herbicides (carryover risk) in the Midwest Cover Crop Field Guide: Also visit the Purdue Extension Weed Science page for additional information on herbicide mode-of-action at: Contact your local NRCS office for assistance in selecting cover crop plant species and seeding rates. Issues of this publication as well as additional NRCS Agronomy Resources are stored at:
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