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Fluid Journal : Fluid Journal 2002-2004
1 Fluid Journal Late Spring 2003 Using Starters to Reduce Broadcast Applications of P in Sugar Beets by Drs. Albert L. Sims and Larry J. Smith Studies show P starters produced yields equal to or exceeding those produced by larger rates of P applied through broadcasting. Summary: Results of the 2002 growing season are similar to what has been observed in previous years (2000 and 2001). Application of a small amount of a fluid phosphorus (P) fertilizer banded in the furrow with the seed produced yields similar to or exceeded those yields obtained with a much larger rate of granu- lar P broadcast. Phosphorus fertilizer is a significant investment in the production of sugar beets. If mismanaged, it can cause environmental problems. The philosophy of P fertilization varies with individuals and organiza- tions. One philosophy recom- mends building soil test levels into the upper medium and high ranges followed by annual appli- cations of P fertilizer to replace P removed by the crop and maintain soil P tests. The University of Minnesota recommends 1) annual soil testing to determine soil test P levels and 2) applying recom- mended P fertilizer rates to optimize production levels. While the university does not recom- mend building soil test levels, strict adherence to university recommendations will lead to a gradual buildup of soil test P. However, this gradual buildup will be accounted for with annual soil testing, and P fertilizer recom- mendations will be adjusted accordingly. Some growers have reported that three to five gallons of 10-34- 0 banded in the furrow with the seed at planting yielded satisfac- tory results without any additional granular broadcast P. Three to five gallons of 10-34-0 supplies 12 to 20 lbs/A of P205. This is consider- ably less P than recommended broadcast rates of granular that might range from 60 to 80 lbs/A of P205 in a low P-testing soil. Banding reduced rates of fluid P fertilizer compared to granular broadcast rates will probably not build soil test P levels and thus could be more environmentally safe. The question is whether it will sustain optimum sugar beet production to allow growers the production levels they need to stay in business. Thus, the reason for conducting experiments to see how sugar beet production is affected when comparing banding reduced rates of fluid P in the furrow with the seed to broadcast- ing granular P at higher rates. Final Yield Generally, sugar beet root yield and sucrose concentration were lower in the 2002 growing season compared to the previous years (2000 and 2001) of this experiment. Part of this was due to 1) planting on May 15, com- pared to early May or late April in previous years, 2) delayed emer- gence due to cold, dry conditions, and 3) several heavy rainfalls during critical times of the grow- ing season. Nevertheless, com- parisons of treatments are valid. Root yield. Sugar root yield in the check plot (no P fertilizer) was about 13.5 tons/A and increased to nearly 20 tons/A with 60 lbs/A of P205 broadcast as granular Figure 1. Sugar beet root yield re- sponse to broadcast dry P fertil- izer (11-52-0) with and without banded liquid P (10-34-0). 22 20 18 16 14 120 Broadcast P rate (lbs P O /A) 25 Banded P No Banded P Root Yield (tonsA) 15304560
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