Foliar N Impact on Soybean Relative Maturity and Nodulation Activity.

Increasing soybean [Glycine max (L.) Merr.] yield on current production area is a major objective for farmers, and supplementing soybean nodulation with inorganic N has been suggested as a possible management strategy in high yielding environments. Many researchers have experimented with variable rate applications of dissolved urea as a foliar nitrogen source but have experienced insignificant results utilizing one cultivar. A late season N application during reproductive stages has the potential to delay leaf senescence increasing late season photosynthesis, allowing plant to achieve maximum yield. However, the delay in leaf senescence may alter harvest maturity and grain moisture, and excessive N application may stimulate vegetative growth in indeterminate soybeans. The objectives of this experiment are to (i) examine the effect of foliar N application at R3 on relative maturity progression, harvest moisture, grain yield, and quality for multiple soybean varieties, and (ii) examine the impact of foliar N application on nodule activity during the reproductive stages. To address these objectives, a field study will be conducted at two Ohio locations in 2016. A randomized complete block design will be utilized with a full factorial of soybean variety (three group II and three group III cultivars) and foliar treatment (foliar N application and untreated).  Relative maturity progression will be evaluated using NDVI and visual evaluation, and grain will be evaluated for yield and quality. Nodule activity will be evaluated through visual evaluation of internal nodule color. Data will be collected throughout the 2016 growing season and results will be presented.