Submitted to: Nitrogen Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2015
Publication Date: N/A
Technical Abstract: Active crop canopy sensors may be useful tools for predicting yield and improving N management of perennial forage or biomass crops such as switchgrass, especially across variable claypan soil landscapes. The objective of this study was to determine how depth to claypan and N management affect switchgrass canopy reflectance. Depth to claypan (DTC) was measured and ‘Kanlow’ switchgrass was seeded in 2009. During 2011 – 2013, switchgrass reflectance was measured with a Crop Circle ACS210 for two N treatments (0 and 67 kg N ha-1) at first growth, early jointing, and late jointing treatments in four replications with a range of DTC. The relationships between a reflectance index (inverse simple ratio (ISR) = visible / near infrared reflectance) and final switchgrass yield or DTC were examined using regression analysis. Results indicate that canopy reflectance can detect changes (R2= 0.26 – 0.85) in switchgrass yield caused by N management and DTC, and accuracy is greater at earlier growth before saturation. Thus, canopy sensors have potential as site-specific yield and N management tools for this crop.