Planting Date and Phosphorus Fertilizer Placement Effects on Winter Wheat
1999
Sander, Donald H. | Eghball, Bahman
Two banding methods of applying P to winter wheat (Triticum aestivum L.), seed and knife (dual placement), have generally performed similarly when averaged over years and locations. However, performance can vary considerably from year to year, or even between locations. This study was conducted to determine the effect of optimal and delayed date of wheat planting on the performance of seed-applied and knifed P on grain yield, P uptake, and yield components. Four rates of P (0, 11.2, 22.4, and 33.6 kg P ha⁻¹) were seed- and knife-applied on a Sharpsburg soil (fine, smectitic, mesic Typic Argiudoll) and Crete soil (fine, smectitic, mesic Pachic Argiustoll) in 1986 and two Crete soils and one Wymore soil (fine, smectitic, mesic Aquertic Argiudoll) in 1987. There were two planting dates in 1986 and three in 1987. All five soils had soil P test levels of low to very low (Bray and Kurtz P1 of 5 to 7 mg kg⁻¹). While seed and knife application performed similarly with an optimum planting date, seed application was a superior P application method in terms of grain yield and P uptake when planting was delayed. The primary reason for the superiority of seed P application was its ability to stimulate tillering and head formation at the later planting dates. The difference in performance between the two methods of P application was probably related to quicker root access to the fertilizer P in the fall soon after planting. Root access to fertilizer P in the fall influences the number of tillers developed, which determines head number at harvest and final grain yield. Results of this research suggest that, when wheat planting date is delayed, fertilizer P should be applied with the seed for maximum effectiveness.
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