ABSORPTION OF FERTILIZER PHOSPHORUS BY SUGAR BEETS AS INFLUENCED BY PLACEMENT OF PHOSPHORUS AND NITROGEN

Abstract

A greenhouse study was conducted to determine the effects of placement of phosphorus and nitrogen on absorption of fertilizer phosphorus by sugar beets. Seven placements of P-32-labelled concentrated superphosphate combined with three nitrogen treatments—ON, 20 lb. N mixed with the soil, and 20 lb. N applied with the phosphorus—were used. The nitrogen source was ammonium nitrate. The phosphorus placements included three band placements, two applications mixed with 2 inches of soil at the 3–5 inch depth with and without a starter, and two applications mixed with 2 inches of soil at the 0–2 inch depth with and without a starter.The placement of nitrogen had a greater influence on the uptake of fertilizer phosphorus than did the placement of phosphorus. Nitrogen applied with the phosphorus generally resulted in greater uptake of fertilizer phosphorus than did nitrogen mixed with the soil. The nitrogen was more effective when the phosphorus was banded than when it was mixed with a volume of soil 2 inches deep. When no nitrogen was added or when nitrogen was mixed with the soil, a shallow band placement or the applications mixed with 2 inches of soil were equally effective in supplying phosphorus to the plant, and were superior to either a deep band or a mixed application with a starter. However, when nitrogen was added with the phosphorus, the shallow and deep bands were equally effective and were superior to the mixed applications with or without a starter.