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Fluid Journal : Fluid Journal 2005-2007
Early Spring 2005 Starter Applications of APP Show Positive Response in Sugarbeet Trials Drs. Bryan Hopkins and Jason Ellsworth Summary: This project evaluated the effectiveness of ammonium polyphosphate (APP) starter fertilizer applied as either broadcast or banded at three different soil depths at three Idaho locations over two years. Banding APP six inches below the soil's surface resulted in increased sugar production at two sites due to a combined increase in sugar percent and total yield. A combination of relatively low yields, warm spring soil, late planting date, and early harvest date are most likely the reason the third location showed no response to starter fertilizer. The broadcast application did not increase yield at any location. The surface and the three-inch band showed a positive response for sugar production at one location, although the magnitude was not as great as that observed with the six-inch band. However, the surface band showed a yield decrease at one location. Although some discrepancies exist between locations, banding at the sixinch depth resulted in the highest total sugar production for two of the three site years of data. Surface banding APP (10-34-0) did not show increased sugar percent or yield; at one site it significantly reduced sugar yield. Fluid Journal 1 Studies in the North-Central U.S. have shown yield increases with the use of 12 to 20 lbs/A of P2O5 as APP starter in sugarbeets. Researchers have found that yields increase when a starter band is placed 1) in direct seed contact, 2) two inches below the seed, and 3) two inches below and two inches to the side of the seed. However, they also have found that the magnitude of the response is delayed and reduced as the distance between the seed and the starter fertilizer band increases. Others conclude that direct seed contact is the best option owing to rapid, vigorous response and because much of the soil in which sugarbeets are grown in that region is high in clay and susceptible to poor seed conditions due to implement- soil interface compaction. Unlike many other crops, these studies have found little advantage for placing the starter band two inches to the side of the seed. Still other research also supports the view that optimal placement of starter fertilizer for sugarbeets seems to be directly below the seed. Sugarbeet growers in other regions have research-based starter fertilizer recommendations, but soil and management conditions in the Western U.S. are unique and those recommendations may not be applicable. There are no published scientific studies evaluating starter P fertilizer for sugarbeets in the western region and in particular, calcareous soils. Many western growers do not apply starter fertilizer with sugarbeets owing to previously observed problems with germination and emergence. However, these observations were primarily made at high rates of starter and with fertilizer having high potential for salt, ammonia, and biuret injury to seeds and seedlings in alkaline soils. Western soils tend to have relatively high pH, carbonates and salts, and low organic matter and clay content and, as a result, have increased likelihood of P deficiency, ammonia toxicity, salt injury, and surface crusting. Although researchers have shown declining impact as P bands increase in distance from the seed, Idaho soils tend
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