EFFECTS OF RATE AND PLACEMENT OF PHOSPHORUS, pH, AND TEMPERATURE ON THE EARLY GROWTH, PHOSPHORUS, BORON, AND ZINC CONTENT OF CORN

The effects of rate and placement of phosphorus (P), liming, and temperature were assessed in terms of yield, P, boron (B), and zinc (Zn) contents of corn grown on a podsol under greenhouse conditions. Yield was 5–10 times greater at 20 C than at temperatures progressing from 9.6 to 19.3 C over 8 weeks. There was also a greater response to applied P at high temperatures. At low temperatures, a small amount of P (17 kg/ha) placed with the seed was as effective, as much larger amounts banded. Liming increased P uptake but not growth, and in one experiment reduced growth when pH levels were raised to 6.0 and 6.5. The reduced yield due to liming appeared to be associated with greatly reduced Zn uptake. Applied P also reduced Zn content but not uptake. Boron content was not affected by treatment.