Comparative response of corn and soybean to seed-placed phosphorus over a range of soil test phosphorus.
1997
Lauzon J.D. | Miller M.H.
The responses of corn and soybean to seed-placed fertilizer were compared over NaHCO3-extractable soil phosphorus (P) levels ranging from 3 to 35 ppm in a two-year experiment. Early season corn and soybean shoot-P concentrations were increased with increasing soil test P and were increased with seed-placed P regardless of soil test P, although the increases were greater for corn than soybean. Corn grain yield increased with increasing soil test P to a plateau level and increased with seed-placed P regardless of soil test P. A side-band (5 cm X 5 cm) application of 39 kg P ha-1 at a low soil test P increased yield more (P < 0.15) than application of 7 kg P ha-1 with the seed. A side-band application of 9 kg P ha-1 at a medium soil P test did not increase yield. Soybean yield was increased with increasing soil test P one year out of two, but did not respond to seed-placed P in either year. The yield response of corn was attributed to the increased P concentration prior to the 6-leaf stage.
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