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Fluid Journal : Fall 2013
15 The Fluid Journal Fall 2013 Figure 5. Soybean yield response to starter fertilizer application with or without micronutrients. Figure 6. Corn and soybean yield response to foliar fertilizer application with or without micronutrients. Summing up Corn early growth (V6) was significantly increased with starter fertilizers (Figure 1). However, the addition of micronutrients with the starter (Zn, Mn, Fe, Cu, B) did not contribute to additional plant growth at this stage. Increase in corn plant early growth with starter fertilizers is attributed primarily to N and P fertilizer. Secondary and micronutrients would not be expected to increase early growth. Micronutrient uptake at V6 growth stage followed a similar tendency as plant growth (Figure 2). This suggests that increase in plant growth contributed to nutrient uptake in greater extent compared to tissue nutrient concentration. However, some micronutrients such as Zn and Cu tissue concentration were increased with the addition of fertilizer micronutrients in the starter. Soybean height at maturity was maximized by an NPKM starter fertilizer treatment without foliar fertilization, with an increase in height of 3 inches over the control. Yield. Corn grain yield was increased across locations with starter fertilizer treatments. However, no additional grain yield increase occurred with micronutrients in the starter (Figure 3) although one location in 2012 did show an additional increase by using an NPK starter with the addition of micronutrients (Figure 4). The soil at this location was sandy (80% sand) and very low in OM content (0.9%). It is likely that these soil conditions contribute to grain yield response to micronutrient application. Micronutrients may be beneficial under specific soil conditions. Soybean yield was increased with starter fertilizers. However, yield increase with micronutrients was not statistically significant despite an average increase in yield across locations (Figure 5). No yield increases were measured in corn or soybeans even when a yield response was measured with starter fertilization (Figure 6). The results of this study suggest producers have a higher probability of response to fluid fertilization at planting compared to foliar application during the growing season. Dr. Mueller is Assistant Professor in the Department of Agronomy, South Dakota State University, and Dr. Ruiz Diaz is Associate Professor and Soil Fertility Specialist in the Department of Agronomy at Kansas State University.
Late Spring 2013