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Fluid Journal : Fluid Journal 2002-2004
2 Fluid Journal Spring 2002 20-0-0+0 Zn 20-20-0+0 Zn 20-20-0+1 Zn 20-20-0+1 Zn band band band broadcast 50 40 30 20 10 0 -10 -20 Starter Cost Additional Net Return @ $15/cwt beans Additional Net Return @ $20/cwt beans Starter Cost and Net Return to Fertilizer ($/A) Figure 2. Starter fertilizer cost (quote from dealer) and net return to fertilizer treatments at two bean prices. Net return is calculated by subtracting starter cost shown from increased crop value over no- starter control. 120 100 80 60 40 20 0 Barley Yield - bu/A Urea UP AS ACI No Mn 5 lbs Mn/A Figure 3. Barley response to Mn banded with starter fertilizers. UP = urea phosphate; AS = ammonirm sulfate; ACl = ammomium chloride. 140 120 100 80 60 40 200 Corn Yield - bu/A SNT DAP AST No Mn 9 33 58 Percentage of Mn in Water Soluble Form Figure 4. Corn response to Mn applied with star ters of varying pH. Manganese was applied at 10 lbs/A. SNT=Mn banded with sodium nitrate + triple super phosphate. AST= Mn banded with ammonirm sulfate + triple super phosphate. 4. Beans planted into wet soil 5. Dry beans that are very sensitive to Zn deficiency. When combinations of factors favoring response occur simultaneously, they increase the likelihood of dramatic response, even in high-testing soils. Though the observed yield increases in Figure 2 may seem modest, they were economically important. The starter response was consistent across varieties and was not limited to early plantings in cool soils. Response of late plantings to starter was similar to early plantings. Seed quality from late plantings that were subjected to frost before harvest was significantly improved by adding Zn in the starter. With acidic starter One opportunity for enhancing micronutrient availability in starters is through placement with acid or acid forming N and P fertilizers. Because micronutrient availability is so strongly affected by soil pH, a small pH change in the presence of an elevated micronutrient concentration can considerably enhance availability. One study showed improved Mn uptake and increased yields on alkaline soils in Oregon when Mn was banded with ammonium sulfate or ammonium chloride but not when Mn was banded with urea (Figure 3). Manganese uptake increased with ammonium sulfate or ammonium chloride without Mn application, but the greatest Mn uptake and yields occurred with the combination. Broadcasting the same combinations produced smaller yield increases and no increase in Mn uptake. Ammonium sulfate and ammonium chloride decreased soil pH and increased soil solution Mn concentration in the band. Studies in acid soils of North Carolina (Figure 4) reported similar results with band combinations of Mn in three starters of varying pH: 1. Diammonium phosphate (DAP) 2. Sodium nitrate + triple super phosphate (SNT) 3. Ammonium sulfate + triple super phosphate (AST)
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