Input Management for Improving Double-Crop Soybean Management.

Double-crop soybean is a valuable production system in Oklahoma due to the large amount of wheat acres in the state. However, due to environmental conditions present throughout the state, this is considered a high risk, high reward crop. As a result of these typical unfavorable conditions, input management is a needed in order to not only decrease production risks and increase productivity. A trial was established in Perkins, Oklahoma on a sandy loam soil. Six inputs were evaluated (previous wheat variety, seeding rate, row spacing, insect and fungicide management, in-season N management, and seed treatment. These were evaluated based on a standard practice level and a high management level (i.e. farmer practice for N-management would be no additional N applied and high management would be 55 kg ha^-1 N applied). In addition, a standard practice and high rate management check was added by fixing all inputs at those individual levels to allow comparison of the individual inputs. Stand counts were taken at the V3 and stand counts, plant height, and yield characteristics were taken at R8. Yield was determined by mechanically harvesting the middle 1.67 meter of the plot. The high input system resulted in significantly higher yields than the standard practice system. Compared to high management system, only decreasing seeding rate resulted no significant differences (54.1 kg ha-1 increase) with all other treatments resulting in significant decreases (185.9 to 341.6 kg ha-1 decrease). This could indicate that higher seeding rates resulted in too many plants per hectare within a double crop system. This increase in yield was possibly due to increased seed weight lower plant population resulted in a significant decline in pods per plant and no significant differences in the number of 2/3 bean pods.