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Title: POSITIONAL AVAILABILITY OF PHOSPHORUS FROM SURFACE FERTILIZER BANDS

Author
item Kovar, John
item Schroeder, Philip
item WASHBURN, JR., K - TWIN STATE, INC.

Submitted to: Proceedings of Great Plains Soil Fertility Conference
Publication Type: Proceedings
Publication Acceptance Date: 3/3/2004
Publication Date: 3/3/2004
Citation: Kovar, J.L., Schroeder, P.D., Washburn, Jr., K.L. 2004. Positional availability of phosphorus from surface fertilizer bands. In: A.J. Schlegel (ed.). Proceedings of Great Plains Soil Fertility Conference. March 2-3, 2004, Kansas State University, Manhattan, KS. p. 271-276.

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, this "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. During three years of field trials, 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 three to four inches into the soil profile. These higher levels of plant-available P in the root zone could benefit the corn plant throughout the remainder of the growing season. 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: Our objective in this field study was 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. Research was conducted during three years (2001-2003) at three locations in central Iowa. Exchange-resin membranes were used to characterize P movement. Treatments consisted of a control and 15-30-10 or 60-30-10 starter dribbled (30 gal./A) on the soil surface two inches to the side of the corn row at the time of planting. In 2001, the highest concentration of bioavailable P was found more than three inches below the soil surface 43 days after application of 60-30-10 starter. In 2002, the highest concentration of bioavailable P at 43 days after application was found more than four inches below the surface for the 15-30-10 treatment, but application of 60-30-10 had little measurable effect. At 68 days after application, the highest P concentration was measured at a depth of less than two inches below the surface for the 15-30-10 starter treatment, and more than three inches below the surface for the 60-30-10 treatment. Similar results were found from measurements in 2003. Given that P diffusion in soil is a relatively slow process, the volume of material (30 gal./A) and the porosity of the soil probably played a role in P movement. In any case, the increased levels of bioavailable P in the root zone could benefit the plant throughout the remainder of the growing season.