|Held, Dr. Larry|
|Stevens, William - Bart|
|Bradley, Dr. Edward|
Submitted to: Journal of American Society of Farm Managers and Rural Appraisers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2007
Publication Date: 7/10/2007
Citation: Taulealea, S., Held, D.J., Stevens, W.B., Bradley, D. 2007. Precision fertilization of Wyoming sugar beets: A case study. Journal of American Society of Farm Managers and Rural Appraisers. 70:44-47.
Interpretive Summary: With the increasing availability of variable rate (VR) fertilizer application equipment, producers and agronomists need more information as to whether this technology is economical. Many producers use a split N application with 50 to 67% typically being applied pre-plant and the remainder as a side dress (post emergent) application. Although VR side dress application of anhydrous ammonia has been reported in corn production systems, there is no information available on the use of VR side dress N applications in sugar beet production. The objective of this two-year on-farm study was to conduct an agronomic and economic evaluation to determine whether VR will improve the productivity and profitability of sugar beet production compared to uniform rate (UR) fertilizer application under furrow-irrigation. Three sites were selected (#1 in 2001 and #2 and #3 in 2002) on an operating sugar beet farm in northwest Wyoming that varied in size from 35 to 60 acres in size. Treatments were applied to field-length strips and replicated three times. Sixty-seven percent of the nitrogen fertilizer requirement was broadcast uniformly prior to planting for all plots. After emergence, the remaining N was applied as a side-dress treatment using either VR or UR application methods. The full length of each field strip was harvested using commercial-scale equipment with trucks being weighed after receiving the harvested beets from each plot. Results from three site-years showed a consistent, but nonsignificant 0.5 ton acre-1 yield advantage for VR compared to UR fertilizer application. Comparing net returns, VR returned $23 and $65 acre-1 more than UR at site #1 and site #3, while UR returned $4.00 acre-1 more than VR at site #2. Because of these inconsistent and small net return differences, VR side-dress application of N fertilizer does not appear to offer a clear economic advantage to sugarbeet producers. However, benefits of VR application may be greater on larger fields with greater soil variability than those evaluated in this study.
Technical Abstract: Field Studies were conducted on a farm in northwest Wyoming to compare variable-rate fertilization (VRF) with uniform-rate fertilization (URF) of sugar beets. Results from this study failed to show an economic advantage from VRF compared to URF, implying producers should be very cautious to adopt VRF technology, unless field fertility needs are highly variable.