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Fluid Journal : Fall 2012
and Mn were chelated with EDTA. Iron was chelated with HEDTA, and B was derived from boric acid. Application. Starter fluid fertilizer and foliar fertilizers were applied in various combinations in a factorial arrangement. Starter fluid fertilizers were applied near the seed using a dribble band placement. The procedure for fluid fertilizer application simulated procedures commonly used by producers. Foliar fertilizer was diluted into water and applied with a hand-held CO2-powered sprayer. NPK was foliar applied using a 10-10-10 fertilizer formulation. Timing. Foliar fertilizer application was made before the plant begins the rapid increase in nutrient and dry weight accumulation. For corn, foliar application was around the 6- to 8-leaf grown stage and for soybeans around the 5 to 7 trifoliate. What happened Soil test. Average soil test levels are presented in Table 1. Plant analysis. Soybean leaf analysis showed a significant increase in B concentration with the addition of micronutrients in the starter fertilizer. Concentrations of Cu, Fe, and Zn were similar to the control. Manganese concentration was decreased with the addition of Mn in the starter fertilizer (Figure 1). A decrease in Mn concentration in soybeans with the use of a chelated (EDTA) source has been observed in previous studies. Plant nutrient analysis in corn showed an increase in Cu and Zn concentration with the addition of micronutrients into the starter, however other nutrients showed no clear difference (Figure 2). Yield. Average soybean yield across sites was slightly higher when micronutrients were added to the starter fertilizer (Figure 3). This suggests that a lower Mn tissue concentration may not be necessarily indicative of yield response in this case. Early growth. Early growth in corn was significantly increased with starter fertilizers compared to the control (Figure 4). The addition of micronutrients in the starter fertilizer did not contribute to additional growth, thus it is likely that the effect in early growth is contributed by N and P. Foliar application of N (derived from methylene urea and triazone) in corn showed average yield increases at all locations in addition to preplant N application (Figure 5). This suggests a possible additional benefit of foliar applications. Additional studies should evaluate different rates and application timing. Figure 3. Effect of starter fertilizers with and without micronutrient application on soybean yield increase compared to the control. Figure 4. Increase in corn early growth biomass (V6) as affected by starter fertilizer treatments compared to the control. Asterisk (*) indicates statistically significant difference from zero at P≤ 0.05. Figure 5. Foliar nitrogen fertilizer application to corn at 4 locations during 2010 and 2011. Probable values for mean comparisons are included for each site. Pre-plant N rates were: Loc 1: 180 lbs; Loc 2: 200 lbs; loc 3: 150 lbs; loc 4: 200 lbs N/acre. Dr. Ruiz Diaz is an Assistant Professor and Soil Fertility Specialist and Dr. Mueller is a Research Assistant in the Department of Agronomy at Kansas State University.
Late Spring 2012