Dale Gies farms about 8 miles south of Moses Lake, Washington. For six years he has been using a two-year rotation of wheat and potatoes with good results. He attributes much of his success to the use of a white mustard green manure crop between the wheat and potatoes. He believes that the mustard makes this short rotation possible. From 1999 to 2001 WSU Extension worked with Gies to document the benefits of the mustard and to investigate the possibility of eliminating fumigant treatments on his best fields.
The specifics of the Gies system are outlined here: Gies System Profile
On-farm research results 1999-2001 are outlined here and explained further in the text below: Gies Research Results
Explanation of On-farm Research Results
Potato Yields/Fumigant Replacement Trials
- All the fields where the research took place had been in the two year rotation (see Gies System Profile above) for at least six years.
- There were no treatments without mustard. The data shows that there is no benefit from using metam sodium, in this rotation, and after a mustard green manure crop.
- Because the Russet Norkotah potato is a shorter season variety than most potatoes used for processing, and because it is being grown for fresh market where certain quality characteristics are not as important (specific gravity, surface markings by nematodes) the results should not be extended to rotations of longer season potatoes such as Russet Burbank, Umatilla, or Ranger.
- Yields were measured from hand dug, 10′ sections of the same row when possible. Where skips occurred in the sample row, adjacent rows were used.
Mustard Green Manure Crop Estimated Variable Costs
- The costs are calculated for a specific system (see Gies System Profile above) and may be different in other systems.
- These are cash costs, which do not include the cost of ownership of the machinery used in field operations. The costs for custom work will be higher.
Green Manure Trials
- 1999 and 2000 measurements were taken in commercial fields. 2001 measurements were taken from smaller plots.
- All 2001 entries had no hard or dormant seed.
Mustard Planting Date and Mustard Nitrogen Response Trials
- These are only only year’s data and should be used with caution.
Soil Quality Measurements
- Infiltration times were taken using 6″ rings and 1″ of ponded water, applied repeatedly. At least 8 replications were used in each measurement and then averaged.