Development and Demonstration of a New Method of Physical Weed Control
Soil Management Research
2013 Annual Report
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.
This research relates to the following objectives: engineer, field-test, and demonstrate a novel method of post-emergence weed control that employs abrasive grit propelled by compressed air and development of field-scale equipment and intensive field validation. During FY 2013, two important contributions were made regarding the use of air-propelled abrasive grit for postemergence weed control. The first was submission and acceptance for publication of a manuscript that describes the 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 was testing the 4-row grit applicator on an organic farm. A brief video of the implement in operation can be viewed at http://www.ars.usda.gov/Services/docs.htm?docid=22766. Preliminary evaluations of weed control and corn response are quite promising.