Feasibility of Grain Sorghum Ratoon Cropping in Northeast Louisiana.

There’s interest in evaluating grain sorghum ratoon cropping in northeast Louisiana. To be feasible, the main crop and ratoon crop, the second crop from the original stubble, must be productive and profitable. The burning questions are yield potential of planted (main crop) and ratoon crop and an input costs associated with insect and disease pressure, particularly for the late-developing ratoon crop. Field experiments were conducted on Commerce silt loam in 2013 and 2014 and Sharkey silty clay in 2015 at the Northeast Research Station near St. Joseph, LA to evaluate the feasibility of sorghum ratoon-cropping in northeast Louisiana. The official variety trials (OVT’s) were used each year for evaluating treatment effects. There were 24, 29, and 31 hybrid entries in 2013, 2014, and 2015, respectively. As a result of potential bird damage, heads in some plots in 2015 were covered with mesh bags for ensuring a good estimate of yield potential. In 2014, an early freeze terminated grain development prematurely. Yields averaged 109 bu/acre in the main crop and 14 bu/acre in the ratoon for 24 entries in 2013 and 104 bu/acre in main crop and 21 bu/acre in ratoon for 31 entries in 2015. Thus, ratoon harvest was only 13% of main crop yield in 2013 and 20% of main crop yield in 2015. Yield for four hybrids in 2015 with protected heads yielded 54 bu/acre in ratoon compared to 106 bu/acre in the main crop. Each yield component, heads/acre, seed weight, and seed/head, were lower for ratoon versus main crops. Multiple insecticide applications were applied each year on the ratoon crop for insect pests, including aphids, armyworms, and sorghum midge. Both limited yield potential and need for multiple pesticide applications for the ratoon crop, suggests that grain sorghum ratoon cropping may not be feasible in northeast Louisiana.