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Submitted to: Fluid Fertilizer Foundation Symposium Proceedings
Publication Type: Proceedings Publication Acceptance Date: 2/19/2002 Publication Date: 2/19/2002 Citation: KOVAR, J.L. FACTORS AFFECTING N AND P NEEDS IN STARTERS: FORMULATIONS AND PLACEMENT FOR REDUCED-TILLAGE CORN. FLUID FERTILIZER FOUNDATION SYMPOSIUM PROCEEDINGS. 2002. V. 19. P. 12-20. 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. With a field experiment, we found that nitrogen and phosphorus fertilizers applied in or near the seed furrow had no negative effect on seed germination and early growth of the crop, but did not boost corn grain yields. A lack of adequate rainfall during the middle of the growing season probably limited the effect. The results suggest that this production practice may be an inexpensive and environmental-friendly way to promote maximum soil productivity, which will certainly benefit those involved in production agriculture. Technical Abstract: Recent research has shown that application of starter fertilizer may alleviate nutrient stress associated with poor root growth early in the season, which often results in a yield response. To investigate, field plots were established on a Canisteo silty clay loam soil in Boone County, Iowa. Before planting, N fertilizer (UAN, 32-0-0) was applied to all plots, so that each received a total of 150 lb. N/A. The starter fertilizer treatments were: i) control; ii) 6-20-0 (5 gal/A 10-34-0), in-furrow; iii) 6-20-6 (8.7 gal/A 7-21-7), in-furrow; iv) 14-48-0 (12 gal/A 10-34-0) 4-in. surface band over row; v) 16-48-16 (21 gal/A 7-21-7) 4-in. surface band over row; vi) 15-30-10, dribbled over row and 2x0; vii) 30-30-10, dribbled over row and 2x0; viii) 45-30-10, dribbled over row and 2x0; ix) 60-30-10, dribbled over row and 2x0; and x) 12-30-14 (8-21-10 dry material) applied as a "T" band over row. Starter fertilizer had no effect on emergence, with a mean of 90.3% and values ranging from 88% to 92%. The N, P, and potassium (K) contents of plants at the 4- to 5-leaf stage were in the optimum range; however, at mid-silk, the K content of the ear-leaf tissue was below the sufficiency range. Given that precipitation was below normal during this part of the growing season, the soil supply of K via diffusion may have been limited. In 2001, starter application had no effect on grain yield, regardless of starter composition or placement. In addition to the crop measurements, the movement of P from the application band into the soil profile was evaluated. Although starter material (60-30-10) was applied on the soil surface approximately two inches to the side of the row, the highest concentration of bioavailable P was found at a depth of more than three inches below the surface. These increased P levels would be of benefit to the plant when root length density reached a maximum at tasseling. |
