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Fluid Journal : Fluid Journal 2005-2007
Early Spring 2005 Fluid Journal 2 to be very high in surface P and very low in subsurface P. This scenario works well for shallowrooted crops such as potato, but may be problematic for sugarbeets because of their dominant tap root system. It is probable that sugarbeet seedlings have adequate P at germination in soils with very high P levels, but there is concern that P availability is insufficient as the sugarbeet taproot explores relatively less of the surface soil and more of the subsurface soil during the first seven to nine weeks of growth. Banded P may enhance subsurface P uptake if placed relatively deep in the path of the sugarbeet taproot. This is especially the case as the availability and diffusion rates increase when P is applied in a band application. The purpose of this project is to determine if deep-banded P enhances sugarbeet P nutrition and if so, how this impacts fi nal yield and sugar content. 2002 results Study involved broadcasting and banding 0, 20 and 220 lbs/A of P2O5 as phosphoric acid (PA) or APP. Banding placement depths were 0, 3, and 6 inches below the seed. Response showed significant increases in yield for the APP applications at both rates and at all three placement depths. Total sugar also increased for all three APP depths, but only the 6-inch depth was significant. Surprisingly, none of the PA treatments showed increases in total or sugar yield, leaving the reason for the APP increases in doubt. Was the reason for the APP increase due to N or P or both? Did the PA suppress yield due to acid-induced P solubility reduction known to occur several weeks after application in high pH soils? In order to answer these questions and avoid further confusion, the study protocol for 2003 was changed to the format described below. The inclusion of the urea ammonium nitrate (UAN) treatments in 2003 served to separate the N contribution of the starter. 2003 results Methodology for the two locations in the 2003 study was similar to the 2002 study with the exceptions of replacing PA with UAN and omitting the high starter rate. Results from the Twin Falls location showed no significant difference in total yield, sugar percentage, nitrate concentration, or total sugar production (Table 1). It is likely that a combination of relatively low yields, unusually warm spring soil, late planting date, and early harvest date resulted in increased P solubility/ reduced P need. Results from the field near Blackfoot also showed no significant difference in sugar percentage and nitrate concentrations (Table 2). However, total yield and net sugar production (Figure 1) proved to have significant differences. The APP applied 6 inches below the soil surface was the only treatment significantly greater than the check. In contrast to the results from the Twin Falls site and previous year results, the surface-applied APP (0 inches) resulted in a significant decline in sugar production. No other treatments resulted in increases or decreases in yield. Although the results from the three locations for the 2003 and 2002 studies were different, it is interesting to note
Fluid Journal 2002-2004
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