Agronomic Responses of Hard Red Winter Wheat to Different Liming and Phosphorus Fertilizer Strategies in Acid Soils.

It is estimated that nearly 40% of wheat fields in Oklahoma have a soil pH lower than 5.5, a level that is thought to reduce forage and grain yields of many wheat cultivars.  Application of agricultural lime is generally considered to be the most effective method for correcting soil acidity; however banding phosphorus (P) fertilizer or pelletized lime with the seed are also used by farmers in managing low pH soils. The objectives of this study were to evaluate three soil acidity amelioration strategies for wheat production. The study was initiated prior to the 2009-10 wheat production season near Waukomis, OK and repeated in the 2010-11 season on a soil with an initial pH of 4.9. A randomized complete block design with four replications was used. Treatments included a non-treated control, 2240 or 4480 kg ha^-1 ECCE agricultural lime, 225 or 450 kg ha^-1 in-furrow pelletized lime, and 30 or 60 kg ha^-1 in-furrow triple superphosphate (0-46-0).’Fuller’ wheat, which has good yield potential but is sensitive to low soil pH, was sown in mid October each year. Plots were soil sampled to evaluate soil pH before planting and after harvesting. The spatial distribution of pH change due to the different treatments was assessed opening a trench in each plot and measuring the soil pH in different points of the profile using a hand pH probe. In-furrow application of P increased late-fall and mid-spring vegetative growth both years of the study and agricultural lime treatments increased vegetative growth the second year. Wheat grain yield was not affected by any of the treatments in this study. Bulk soil pH was increased by the use of broadcast agricultural lime; however, no differences were observed among the other treatments. Pelletized lime only changed soil pH in the region surrounding the pellet, and the change was much smaller than that caused by broadcast agricultural lime. The results of this study indicate that in-furrow application of triple superphosphate or broadcast agricultural lime increase early-season wheat growth in a low-pH soil but this increased vegetative growth might not result in increased grain yield.