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Submitted to: Fluid Fertilizer Foundation Symposium Proceedings
Publication Type: Proceedings Publication Acceptance Date: 2/24/2004 Publication Date: 2/24/2004 Citation: KOVAR, J.L. STARTER COMPOSITION AND HYBRID SELECTION AFFECT EARLY GROWTH AND YIELD OF CORN. FLUID FERTILIZER FOUNDATION SYMPOSIUM PROCEEDINGS. 2004. V. 21. P. 131-141. Interpretive Summary: Early in the growing season, cool soil temperatures often limit the ability of corn roots to absorb sufficient nutrients and water. An application of a small amount of fertilizer at the time of planting may overcome this problem, leading to better plant growth and higher grain yields at the end of the season. To be effective, however, starter fertilizer must increase the amount of plant-available nutrients in the soil, and the plant root system must be able to take advantage of this increase. With a field experiment, we found that at least some of the phosphorus (P) in starter fertilizer dribbled on the soil surface two inches to the side of the corn row at the time of planting moved into the profile where it could be absorbed by corn roots. In a separate experiment focused on differences among corn hybrids in response to starter fertilizer, we found that early-season plant and root growth were similar for two corn hybrids and their genetically-modified counterparts that were resistant to corn borers. The corn borer-resistant hybrids, however, tended to produce higher grain yields, probably as a result of corn borer damage to the non-resistant hybrids. The results of this research will benefit both commercial growers and the fertilizer industry by providing nutrient management alternatives that maximize crop utilization and minimize potential nutrient losses. Technical Abstract: Recent research has shown that application of starter fertilizer may alleviate nutrient stress associated with poor corn root growth early in the season, and set the stage for a yield response. The objectives of this field study were: i) to determine the relative distribution of phosphorus (P) applied as a liquid starter fertilizer in a surface band during the early part of the corn growing season, and ii) to determine whether a response to starter fertilizer is hybrid dependent. Field plots were established on a Clarion silt loam (P bioavailability study) and a Canisteo silty clay loam (hybrid study) in central Iowa. In the first study, exchange-resin membranes were used to characterize P movement. Treatments consisted of a control and 0-30-0, 15-30-10, or 60-30-10 starter fertilizer dribbled (30 gal./A) on the soil surface two inches to the side of the corn row at the time of planting. Higher concentrations of bioavailable P were measured near the soil surface for all three of the starter treatments 23 days after application. By 42 days after application, the highest concentration of P was found one to two inches below the surface for both the 15-30-10 and 60-30-10 starter treatments. At 63 days after application, the highest concentration of bioavailable P was measured at a depth of more than three inches below the surface for the 15-30-10 starter treatment. In contrast, no measurable differences in bioavailable P concentrations were found in plots in which 0-30-0 or 60-30-10 was dribbled on the soil surface. The reason for the differences among the treatments is unclear; however, the results suggest that at least some of the P applied to the soil surface will move into the profile. In the second study, early-season shoot dry matter production and root growth were similar for two non-transgenic corn hybrids (36R10 and 33P66) and their transgenic isolines (36R11 and 33P67). The transgenic corn hybrids, however, tended to produce higher grain yields than the non-transgenic hybrids. This difference was probably the result of corn borer damage to the non-transgenic hybrids. |
