Continuous Spring Crop Rotations

Dick Jones
with Research and Development Department, McGregor Company

Objective

This study evaluates the economics of a continuous spring crop rotation: soft white wheat/canola/hard red wheat/barley. This was the first of a four year study.

Location: Dayton WA
Soil: Athena silt loam
Annual precipitation: 16.5 inches
Normal rotations: Winter wheat/fallow, or winter wheat/spring barley/fallow

Treatments (all spring crops)

1. soft white wheat
2. hard red wheat
3. barley
4. canola

Comments

Our goal is to measure the economic returns for each component of a four-year continuous spring crop rotation. In order to eliminate the problems of year-to-year variations in yield, we have four treatments using the same rotation but at different starting points.

The 80 bushel winter wheat stubble was left standing over winter. Eight ounces of Roundup RT was applied in late February and volunteer allowed to dry down. The field was then burned on March 20 and fertilizer applications made with a Ripper Shooter on March 27. In the future we expect to be able to Ripper Shoot directly into the spring crop stubble. The field was cross cultivated and seeded on March 30. The canola plots required an additional harrowing prior to seeding.

Stored moisture levels were high (11.3 inches available in 6 ft). The residual nitrogen levels were relatively low (112 lb in 6 ft). Based on the amount of stored moisture, long-term weather forecasts predicting an extended cool, wet spring, opportunity to seed early, and the potential for strong commodity markets, we chose to fertilize based on optimistic yield goals.

Data

Plots were 30 by 400 ft, and there were four replications of the four-rotation comparison. Yield was measured by harvesting 22 by 400 ft from the center of each plot.

Yield, bu/ac

Treatment	Rep 1	Rep 2	Rep 3	Rep 4	Average
Soft white (Penawawa)	63	66	62	61	63
Hard red (926R)	61	57	51	49	54

Yield, lb/ac

Treatment	Rep 1	Rep 2	Rep 3	Rep 4	Average
Barley (Baroness)	5554	5309	4955	4574	5098
Canola (Helios)	2069	1980	1475	1772	1822
CV					5.3%

Conclusion

The table of costs and returns shows some very interesting comparisons. The yields of all crops can be considered good, but the gross revenues minus the seed, fertilizer, and chemical input costs (including application) vary from $86 to $216. Tillage and other operating costs are not considered in this analysis. This study will continue three more years so that the effect of previous crop and annual weather variations can be averaged over four years.