Applied Fertility Management for Irrigated Soybean Production

Irrigated soybean yields in North Central Kansas averaged about 53 bu/A over a recent 10-year period from 2000 to 2009. Although yields have trended upward, producers in the area are largely unsatisfied. Past research conducted at the Kansas State University North Central Kansas Experiment Field near Scandia has demonstrated that proper fertility management, including direct application of P and K, has the potential to significantly improve irrigated soybean yield. Despite the findings of this work soybean producers have been slow to adopt intensive fertility management programs. It has been speculated that adoption might be facilitated if these results were demonstrated on farmer fields outside the experiment station. The purpose of this research is to expand upon previous high-yield soybean work by including a field scale, farmer-cooperative component to increase awareness of irrigated soybean yield potential with proper fertility management.

This project will consist of a combination of small fertilizer response plots conducted at the KSU Irrigation Experiment Field and a field scale study on a producer’s field. Small plot treatments will include a zero fertilizer control, and all combinations of 30 and 80 lb P₂O₅/A, and 80 and 120 lb K₂O/A. The effects of N and S will also be evaluated at the higher P and K rates. Field scale plots will be simpler, with one P (30 lb P₂O₅) and one K (80 lb K₂O) rate a combination of the two. This work was planned and cooperation established in late 2011, so results are not yet available. The first year of production will be 2012, and the project is expected to continue for three years. KS-41