Effect of Fertilizer Phosphorus Placement Depth on Winter Wheat Yield

Abstract

AbstractField studies were conducted with winter wheat (Triticum aestivum L. ‘Centurk 78’) at nine locations in southwestern, central, and eastern Nebraska in 1982 and 1983 to determine the effect of phosphorus (P) placement depth (0, 5, 10, and 15 cm). As a comparison to these depths, seed placed P, soil surface placed P, and no P treatments were used. A rate of 11 kg P ha−1 was applied. Soil great groups were either Argiustolls or Argiudolls with surface soil Bray and Kurtz no. 1 P levels ranging from 4 to 9 mg kg−1 and pH values ranging from 5.5 to 7.5. Grain yield was increased by added P in both years though magnitude of response varied at different locations. A linear and quadratic response to depth was evident in both years, though variation occurred between locations. Optium depths of P placement for maximum grain yield occurred at 11.9 cm in 1982 and 10.4 cm in 1983. No differences between either the best depth (10 cm) and seed treatments or the surface and seed treatments were found, indicating that, depending on management situations, these methods of P application could be used interchangeably. Total P uptake was increased by P applications in a manner similar to grain yield. Phosphorus uptake of the seed treatment and the best depth treatment at several growth stages (Feekes' stages 2.0, 6.0, 10.0, 10.5, and 11.4) was compared. An early advantage (stage 2.0) of the seed treatment was not evident at harvest, indicating that early P uptake is not necessary for maximum yield. The number of heads and seed weight were both increased due to applied P in both years and seed weight responded linearly to depth in 1982. No effect on the seed number per head was found.