Evaluations of Alternative Economic Endpoints of Cover Crops in Northern Montana Replacing Fallow in a Crop-Fallow Rotation.

Results from a long term (six year) cover crop (CC) wheat rotation trial will be presented where cover crops were terminated differently to generate alternative economic endpoints. The large scale plots were established with a commercial ConservaPak pneumatic seeder. The rotation was based on a crop-fallow rotation with the CCs replacing the fallow period. Fifteen different polycultures (cool, cool/warm and warm season), continuous crop barley plus the control fallow were established in the fallow year. Each main plot was designed as a split plot with the sub-plot being different termination types (Herbicide, Grazing or Haying). Polycultures established at three times, each appropriate for their respective cool or warm season composition with the cool/warm being intermediate. Termination (cattle grazing, swathing and baling, and herbicide treatments) took place at the same time, when the cool season cereal began to head (mid-July). The CC was terminated at this time to protect deep subsoil moisture for the wheat crop the following year. Forage information, along with soil physical and chemical characteristics across time will be presented. Winter or spring wheat was planted in rotation as a response variable to the previous year’s CC treatment and for comparison to a fallow-wheat two year rotation. Cool and cool/warm season polycultures used more plant available water and produced the most above ground biomass, however, depending upon year, produced the lowest subsequent wheat yields. Two and four year economic gross return in current markets tended to favor generating income in the fallow year over a traditional crop fallow rotation. Implementation of targeted cover crop use may be warranted for diversified operations utilizing cover crops and livestock as an alternative economic strategy to crop fallow. Strategic rains, current wheat, hay and grazing prices and the lack of severe drought impact current long term trends and results.