High Pressure Grit Spraying as an Abrasive Weed Control Method – Brayden Connor
A new organic weed control agent being researched and tried out by a few farmers is the use of grits from processed crops such as corn or tough seed coats. In a study done by Frank Forcella found that even when sprayed in crop in row weed control was up to 90% (2012). The study found that corn crop yield in grit sprayed plots did not differ from hand weeded plot and that high weed control levels can be reached with only two applications through the season (Forcella 2012). In his 2010 paper Forcella indicated that Corn Gluten Meal is already an approved fertilizer for organic agriculture as a nitrogen fertilizer Corn Gluten Meal can also be manufactured as grit for weed control purposes (Forcella 2010). This could add an extra benefit if substances that may provide nutritional value to plants could be used as a pressure fired abrasive to destroy weeds. One could argue that the weeds themselves could also use the nutritional value but the study by Frank Forcella in 2012 leads me to believe they sustain too much damage to be able to use this as an advantage.
Organic producers should pay careful attention to crop and weed stages when treating crops with pressurized grits. Small weeds will sustain the most damage but a seedling crop could be killed as well. Pre-emergence control could be achieved by a grit application to stop fast emerging weeds from beating the crop to limited resources such as sunlight. This grit is essentially “sand-blasted” either onto the whole field or between rows to abrasively damage weeds to give the crop an advantage while the weeds recuperate.
If an application needs to be applied during the early crop stages care should be taken to try to spray between rows to hold damage to a minimum while as the crop becomes larger the damage it sustains will be less problematic for the plant and affect yield less (Forcella 2009).
Costs for this method include the corn gluten meal itself as a grit, as well as pressurized application system. An additional cost would be the time the grower has to take to spray the grit. As corn gluten meal is a completely organic substance spraying it in the crop would have extremely little impact on the environment or surrounding areas except for the weeds it is being directed at.
This system would work best in small plots and areas, as large application systems had not been developed yet. In his 2009 study Forcella used an applicator shown in Figure 1. This hand nozzle would be effective for gardens or small crops and would be easy to control and direct the spray of the grit. I think abrasive grits could be used as a good weed control method for small crops and garden plots but new application systems need to be developed for this to be practical as a control method for large areas.
Forcella, F. (2012). Air-Propelled Abrasive Grit for Postemergence In-Row Weed Control in Field Corn. Weed Technology , 26, 161-164.
Forcella, F. (2010). Post-emergence weed control through abrasion with an approved organic fertilizer. Renewable Agriculture and Food Systems , 26 (1), 31-37.
Forcella, F. (2009). Potential of Air-Propelled Abrasives for Selective Weed Control . Weed Technology , 23, 317-320.