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Fluid Journal : Fluid Journal 2008-2009
12 Fluid Journal WINTER 2008 Continuing studies on corn response to starters on high phosphorus (P) soils on the Delmarva Peninsula indicate that some starter P is important for highest yields even when soil test P levels are high. Eliminating P in starters because of high P index values puts growers at a disadvantage through lower yields, particularly in high residue systems, and likely has negative implications for nitrogen (N) --use efficiency (NUE). RON MULFORD Still Important: Starters On High P Soils Maryland studies show P improves corn yields even when soil P levels are high. Complete starter formulations, including higher amounts of starter N, plus the inclusion of potassium (K), sulfur (S), and zinc (Zn), have proven to be advantageous compared to N-alone starters. Placement Banding vs. broadcast. Placement of fluid starter in a band behind one of the two planter V-shaped press wheels was as effective as placement beside the row with an opener, indicating flexibility in choosing how planters can be equipped for effective application of fluid starters. Maryland studies have consistently shown that broadcast applications of a starter formulation prior to planting have been inferior to banding beside the seed row (2 x 2 placement) or banding on top of the soil beside the row. Broadcast rates of 48-20-5-1S produced some 52 bu/A less dryland corn than the same formulation banded 2 x 2 or behind one of the V-shaped press wheels (Figure 1). At a lower rate of starter N that difference ranged from 8 to 17 bu/A. Evaluations of a banded 25-20- 5-28S-0.6Zn starter on a Mattapex silt loam indicate the equality of 2 x 2 and starter dribbled in a press wheel groove (Table 1). With S rates this high in a starter and placement this close to the seed on a coarse- textured soil, our data suggest that ammonium sulfate may be a better choice (156 bu/A) than ATS plus KTS (146 bu/A) because of some
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