ARS | Publication request: ESTIMATING SWITCHGRASS STANDING CROP WITH VISUAL OBSTRUCTION AND ELONGATED LEAF HEIGHT

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 30, 2003
Publication Date: February 1, 2004
Citation: Schmer, M.R., Mitchell, R., Vogel, K.P. 2004. Estimating switchgrass standing crop with visual obstruction and elongated leaf height. Society for Range Management Meeting Abstracts. #299.

Technical Abstract: A method to accurately and efficiently estimate standing crop on switchgrass fields grown for bioenergy is needed. The objective was to evaluate visual obstruction and elongated leaf height as estimators of standing crop. The study was conducted on eight switchgrass fields in Nebraska, South Dakota, and North Dakota and on small plots in eastern Nebraska. Switchgrass standing crop was estimated in spring and late summer from clipped quadrats in 18 switchgrass fields and machine-harvested passes in 18 plots. Visual obstruction and elongated leaf height means were compared to the standing crop estimates from the clipped and harvested plots. Switchgrass standing crop ranged from 0.55 to 12.6 Mg ha-1. Visual obstruction and elongated leaf height accounted for 81% and 80% of the variation in standing crop on the hand-harvested fields, respectively. Visual obstruction and elongated leaf height accounted for 95% and 90% of the variation in standing crop on the machine-harvested plots, respectively. Height to the bottom of the panicle accounted for 86% of the variation in standing crop on the machine-harvested plots. Visual obstruction and elongated leaf height were strongly correlated (r2 = 0.91). Visual obstruction, elongated leaf height, and height to the bottom of the panicle appear to be accurate estimators of switchgrass standing crop.