Methods and Data Collection
- Experiments were initiated at three locations across the state including Roseau, Morris, and Waseca.
- The plot size of each cropping system is 10’ x 30’ and is replicated four times. The same plot size and replication is consistent across all three sites.
- Winter camelina and field pennycress are double-cropped with soybeans and are compared to winter rye/soybean, radish/soybean, and fallow/soybean rotations.
- All of the rotations will be planted using a no-till system. The control plot consists of soybeans planted using a conventional cropping system in which normal tillage operations and winter fallow are used.
Agronomy
Winter rye and radish will be drill-seeded at recommended rates in late August following harvested spring wheat or corn silage. Pennycress and winter camelina will be drill-seeded in mid-September. Relay-cropped soybeans will be planted in the spring when pennycress and camelina begin to bolt (produce a flowering stem (or stems) before the crop is harvested, in an attempt to produce seeds). Soybean crops following winter rye, radish, and fallow will be planted on the same date or as soon as conditions allow. Tillage radish winter kills while rye will be treated with glyphosate before planting.
Plants will be evaluated for:
- Stand establishment
- Ground cover
- Autumn and spring biomass
- Winter survival
- Seed yield and oil content of pennycress, winter camelina and soybean
Additionally, crop growth will be monitored with crop sensors to determine crop water use and estimated peak biomass. At estimated peak biomass, plants will be clipped and dried to determine nitrogen and phosphorus concentrations.
Soil Water
Researchers will measure soil water content every four hours using sensors placed in the soil at one and three feet deep. Soil samples will be collected three times throughout the growing season, fall, spring and late summer, to verify sensor data.
To determine nutrient loss to surface and groundwater, suction cup lysimeters and soil sampling techniques will be used. Soil samples will be collected at the times mentioned above. Sampling intensity from the lysimeters will vary depending on time of year with a higher sampling intensity occurring during the spring and early summer when nutrient leaching potential is greatest.
Runoff
Researchers will measure runoff water volume and sediment load using Gerlach troughs immediately after or during individual events including rainfall and snowmelt. Measurements will be taken at the Morris site only because of the close proximity to the laboratory. Samples will be measured for nitrogen and phosphorus to determine surface nutrient loss from the field.
Economics
Gross and net returns for the winter oilseed double-cropping systems will be calculated using cropping system budgets. Anticipated commodity prices and fixed and variable costs will be used in the calculations.
A stochastic budget will be employed to account for the variability in commodity prices and uncertainty in yields for each cropping system. This type of budget is more appealing to growers because it accounts for market variability.
