Foliar Potassium Fertilizer Additives Affect Soybean Response and Weed Control with Glyphosate

Figure 3

Soybean grain yield response to K-fertilizer additives (%N-%P₂O₅-%K₂O-%S) of 3-18-18-0 (𝑦=−29.108𝑥²+54.656𝑥+2644, 𝑅²=0.29), 0-0-25-17 (𝑦=−12.009𝑥²−7.91𝑥+2644, 𝑅²=0.62), 5-0-20-13 (𝑦=13.163𝑥²−12.895𝑥+2644, 𝑅²=0.64), or 0-0-62-0 (𝑦=−2.2418𝑥²−10.684𝑥+2644, 𝑅²=0.84) applied alone to weed-free plots (a) and with glyphosate to weedy plots (b) for 3-18-18-0 (𝑦=6.7384𝑥²−44.786𝑥+2947, 𝑅²=0.97), 0-0-25-17 (𝑦=−16.937𝑥²+13.186𝑥+2947, 𝑅²=0.6), 5-0-20-13 (𝑦=−13.38𝑥²−20.337𝑥+2947, 𝑅²=0.89), and 0-0-62-0 (𝑦=1.5132𝑥²+72.982𝑥+2947, 𝑅²=0.98) at Portageville in 2004 and 2005. Data were combined over years, and comparisons between figures are valid. The nontreated, weed-free, and glyphosate plus nonionic surfactant plus diammonium sulfate grain yields were 1160, 2640, and 2120 kg ha⁻¹, respectively. The LSD (𝑃≤0.01) was 670 kg ha⁻¹.

(a)

(b)