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United States Department of Agriculture

Agricultural Research Service

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Location: Soil Management Research

2011 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.

3. Progress Report
This subordinate project formally commenced in winter 2011, when funding from North Central Sustainable Agriculture Research and Education (NC-SARE) through the University of Minnesota was redirected by the project director (PD) to South Dakota State University (SDSU). The redirected funds primarily are in support of a graduate student in agricultural engineering. The graduate student’s thesis topic is the construction of a four-row grit applicator. A beta-test version of the applicator is anticipated for demonstration purposes by August 2011, with field trials to commence in spring 2012. The purpose of the grit applicator is abrasion of in-row weeds, thereby allowing row crops like corn to grow unencumbered by competition from weeds for soil nutrients, soil water and light. Expected progress of the subordinate project increases the likelihood of successful development of integrated sustainable crop production systems on organic farms. The subordinate project directly embraces novel weed control tactics, which is a main objective of the parent project. Since October 2010 the PD organized a meeting at SDSU, which involved the departments of Plant Sciences, Agricultural and Biosystems Engineering, and Engineering Technology and Management. In relation to this subordinate project, the PD organized a planning meeting in April 2011 that included two SDSU professors, one SDSU graduate student, and one SDSU research Associate, as well as four collaborating organic growers, a consulting engineer, and an agronomist and two soil scientists from USDA. The graduate student summarized his research and engineering activities over the winter. He expects to have a beta-test version of the grit applicator ready for demonstration purposes by August 2011.

4. Accomplishments

Last Modified: 06/27/2017
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