100688 Potassium Fertilizer Rate and Timing on Recovering Yield Loss in Potassium Deficient Soybean.
Poster Number 125-525
See more from this Division: SSSA Division: Soil Fertility and Plant Nutrition
See more from this Session: S4/S8 M.S. Poster Competition
Abstract:
Potassium deficiency of is the most common nutrient disorder of irrigated soybean (Glycine max) grown on loamy soils in Arkansas. Unless the K deficeincy is severe, visual symptoms are often not apparent until the R5 growth stage. Information regarding soybean yield response to fertilizer-K appliction time is lacking. The research objective was to evaluate soybean yield response to fertilizer-K application time on a K-deficient silt loam. Fertilizer-K (56 kg K ha-1 as muraite of potash) was applied several weeks preplant and seven times after emergence of a maturity group 4.7 variety. Non-linear regression was used to model soybean yield response to fertilizer-K application time by regressing seed yield against the time fertilizer-K was applied, expressed as days after planting (DAP). At the R2 growth stage, the recently mature trifoliolate leaves (no petiole) of soybean receiving no fertilizer-K averaged 9.85 g K kg-1 compared to 12.6 to 13.6 g K kg-1 for soybeans fertilized with 56 kg K ha-1. Soybean response to the timing of 56 kg K ha-1 was a quadratic function of DAP. The relationship (r2 = 0.74) predicted maximum yield was produced by K applied 3 DAP and 5 and 10% yield losses were predicted for K applied 54 (R2 stage) and 75 (R5 stage) DAP, respectively. Yields were maximized (4289 kg ha-1) only by preplant application of 112 kg K ha-1 which yielded 512 kg ha-1 more than soybean fertilized preplant with 56 kg K ha-1 and 1297 kg ha-1 more than soybean receiving no fertilizer-K. Preliminary results from one trial conducted in 2015 indicate that K-deficient soybeans respond to fertilizer-K until the initiation of seed fill. Results from two additional trials conducted in 2016 using higher in-season K rates will be reported.
See more from this Division: SSSA Division: Soil Fertility and Plant Nutrition
See more from this Session: S4/S8 M.S. Poster Competition