Influence of Fertilizer Additives on Crabgrass (Digitaria sanguinalis) Biomass Production.

Crabgrass is a valuable summer annual forage that can be used for grazing or hay production. The objective of the study was to evaluate cultivar response to nitrogen fertilizer additives. The study was conducted at Mississippi State University in a Marietta Fine Sandy loam soil (Fine-loamy, siliceous, active, thermic Fluvaquentic Eutrudepts). The experimental design was a randomized complete block in a 4 x 5 factorial and replicated three times. Five crabgrass cultivars ‘Dal’s Big River (DBR),’ ‘Impact (I),’ ‘Quick-N-Big (QNB),’ ‘Quick-N-Big Spreader (QNBS),’ and ‘Red River (RR)’ were planted in a prepared seed bed at a rate of 8 lb PLS/ac using an Almaco Drill (Nevada, IA). Cultivars were treated with four nitrogen combinations: control, urea ammonium nitrate (UAN 32-0-0, C), UAN plus N-Veil® (26.7% NBTP, NVEIL), and UAN plus Preserve N™ (18-0-0, PN). Nitrogen was applied at rate of 50 lb N/ac. UAN was treated with N-Veil® and Preserve N™ at a rate of 2.0 qt/ton and applied using a backpack sprayer when plants reached a height of three inches to supply a rate of 25 gal/ac. Lime, phosphorus (P₂O₅), and potassium (K₂O) were applied based on soil test recommendations. Whole plots (6 ft x 10 ft) were harvested three times in 2019 and subsamples were dried at 130 °F for 72 h, ground to pass a 2-mm screen, and analyzed for nutritive value using NIRS and the 2017 grass hay equation developed by the Forage and Feed Testing Consortium (Hillsboro, WI). Biomass was not affected by cultivars. ‘Impact’ had 10% greater yield than DBR. There was no N treatment effect, but treatments containing PN fertilizer additive was lower yielding than the control. Nutritive value (CP, ADF, NDF, and WSC) was not affected. No significant differences were noted for cultivar and treatment effects on CP, ADF, NDF and SWC.