Drought conditions in the northwest region has resulted in low amounts of crop residue being produced. To further complicate this matter, straw has been baled to be used for cattle feed this winter. The low levels and removal of straw will expose our soils to higher chance of erosion in the coming year. This is especially true for fields that are worked this fall and are to be summerfallowed next year. In order to lessen the chance of soil erosion farmers should be planning now how to conserve as much cover as possible.
If a field is to be summerfallowed the most cost effective option is to replace a tillage operation through the use of herbicide application. The most cost effective option is the use of fall or spring 2,4-D application to control the broadleaf winter annuals. Winter annuals include flixweed, stinkweed, and shepherd's purse to name a few. These weeds germinate in late fall, overwinter as rosettes and begin growth early the following year using valuable moisture and soil nutrients. Recommended rates of 2,4-D and MCPA are .34 to .45 liters per acre. Both amine and ester formulations work well for most winter annuals. For a complete list of weeds controlled at the different rates consult the 1995 Crop Protection Guide available at your local Rural Service Center. The use of fall applied 2,4-D can replace up to two tillage operations, i.e. late fall and/or early spring. The removal of this one tillage can save from two to four hundred pounds of straw residue per acre. This amount goes a long way to reducing the potential; amount of soil that could be lost from wind and water erosion over the next two years.
The use a non-selective herbicide like Roundup could be used to replace another tillage operation and conserve even more straw residue. Each tillage pass with a heavy duty cultivator and harrows buries 40% of the residue. The use of herbicides to replace the first two tillage operations will conserve more residue than using herbicides to replace tillage operations later in the season.