Objective 1: In 2013, locations where soil test P values were in the current “medium” or “high” category showed no yield response to P fertilizer. This study is being repeated this growing season (2014) on 10 more additional sites where more sites are testing in the “low” category for soil test P. Early season growth responses to P fertilizer have been observed in 2014. Soil test and leaf P concentration interpretations based on yield and yield components (pods per plant, seeds per pod, etc.) will be averaged across data from 2013 and 2014 growing seasons this fall.

Objective 2: Significant variation in soybean leaf nutrient concentrations across the landscape suggest that multiple soybean leaf samples should be taken in a field for the purpose of monitoring plant nutrition. Final analysis/synthesis of the data still need to be conducted and outreach materials generated.

Objective 3: Paulsen Marketing staff, iGrow staff, and I have met to move designing of the NEW online soybean leaf nutrient interpretation tool forward on a dynamic mobile-friendly platform. The targeted release of the online soybean leaf nutrient interpretation tool for 2014 growing season was ambitious on our part and not met. However progress on the tool is moving forward and will be available for 2015 growing season. The extension article (iGrow.org) and video (YouTube) have already been released.

Objective 4: This portion of the study is being repeated this year at Volga with the same varieties to average across climatic conditions. First year data revealed that several varieties behaved differently in leaf nutrient concentration (Figure 1). Rebecca Slatt, graduate student, will be conducting this analysis across both years this fall for her thesis work. Extension materials will be generated from her work highlighting the implications of sampling at various growth stages and varieties for monitoring soybean plant nutrition.