Agronomic Characteristics of Dual-Purpose Canola Grow in Piedmont Soils of North Georgia.

Canola (Brassica rapa) is quickly gaining popularity as a row crop in several parts of the Southeast, including North Georgia.  However, little data exist on the possibility of utilizing canola as a dual-purpose crop grazed by beef cattle.  Therefore, a study was conducted to determine the forage yield, quality and subsequent seed yield of canola grazed at two grazing pressures.  Sixteen 0.66-ha paddocks were blocked by previous tillage history and randomly assigned to one of four treatments: canola-early graze (CEG), canola-late graze (CLG), canola-no graze (CNG), and grazed winter wheat (WW). Canola and winter wheat were no-till drilled into a prepared seedbed in November 2013 and 24 Angus steers (248 ± 19 kg; 2 per paddock) were randomly assigned to pastures in Jan 2014.  Cattle remained in plots until growth stage 3.0 for CEG treatments and 3.1 for CLG treatments.  Standing biomass, LAI, NDVI, and RPM measurements were taken biweekly and biomass yield, seed yield and seed oil content were determined in June 2014.  Data were analyzed as a CRB using Proc Mixed of SAS.  Leaf area indices and forage biomass were not different (P > 0.265) among treatments (1.8 units and 940 kg DM ha^-1); however, CEG and CNG had a greater (P < 0.029) NDVI than CLG and WW (0.60 and 0.51 units, respectively).  A RPM calibration equation was derived from RPM measurements and destructive samples; y = 141.4x – 350.9 (R² = 0.67).  Winter wheat had the greatest (P < 0.011) seed yield (2932 kg ha^-1).  Canola-early graze had a greater (P = 0.032) seed yield than CLG (2009 and 1238 kg ha^-1, respectively) but neither was different (P > 0.124) from CNG (1467 kg ha^-1).  There was no effect of treatment (P > 0.148) on seed oil content (41.5%).  These data are interpreted to mean that grazing of canola does not affect standing biomass yield and canopy cover.  Additionally, early-grazed canola can produce the same seed yield as non-grazed canola; however, grazing canola to growth stage 3.1 will result in a diminished seed yield.