1a.Objectives (from AD-416):
Engineer, field-test, and demonstrate a novel method of postemergence weed control that employs abrasive grit propelled by compressed air. Development of field-scale equipment and intensive field validation are required for this promising new technique, which is expected to meet certified organic standards.
1b.Approach (from AD-416):
Engineering approaches involve: (i) harnessing a tractor's energy to compress air (~500 kPa) sufficiently for (ii) propelling crop-derived grit in a directed fashion through nozzles at speeds that abrade small weed seedlings selectively within crop rows, (iii) adapting nozzles for optimum patterns of grit application, and (iv) attaching multiple pairs of nozzles onto a tractor-mounted toolbar for simultaneous multiple-row weed control. Field research entails testing: (i) the timing and frequency of application passes, (ii) air pressure or grit air speed requirements, and (iii) grit size and hardness, e.g., walnut (hard) vs. corn cob (soft), to affect season-long control of weeds without crop injury in common annual and high-value perennial row crops. Demonstrations include displays of prototype equipment in action and their selective effects on weeds and crops at field days in Minnesota and South Dakota. Outcomes anticipated comprise: (i) a novel and tangible implement for non-chemical weed control; (ii) two peer-reviewed articles, one in an engineering journal and another in an agronomic journal; (iii) an extension bulletin describing the new system; and (iv) possible patents for the resulting implements. The expected audiences for the project are organic growers and equipment manufacturers. Both audiences will be exposed to an entirely new form of physical weed control that incorporates a novel use for crop residues.
During FY 2012, three important contributions were made regarding the use of air-propelled abrasive grit for postemergence weed control. The first was successful field-testing of the concept in soybean. Previous studies showed that the technique worked well in corn, but the selectivity of the technique in a broadleaf crop was unknown. The second contribution was publication of the field-based testing of the technique in corn in a peer-reviewed journal, Weed Technology. This publication elicited substantial interest from the popular press. The third contribution was completion of the 4-row grit applicator. Several minor engineering corrections were required for proper functioning of the implement, but by mid August 2012 the machine was performing as anticipated. The implement was show-cased and demonstrated at two Field Days in Minnesota. It will be tested extensively in field trials in spring 2013.