|HUMBURG, DAN - South Dakota State University|
|CLAY, SHARON - South Dakota State University|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/7/2013
Publication Date: 2/7/2013
Citation: Forcella, F., Humburg, D., Clay, S. 2013. PAGMan - propelled abrasive grit to manage weeds in soybean and corn [abstract]. Weed Science Society of America Annual Meeting Abstracts. Weed Science Society of America Annual Meeting. Feb. 4-7, 2013, Baltimore, MD. Available: http://wssaabstracts.com/public/17/abstract-128.html.
Technical Abstract: New tools for controlling weeds would be useful for soybean and corn production in organic systems or in systems in which weeds developed resistance to multiple herbicides. Here we report on two developments: (i) the safety to soybean seedlings of using air-propelled abrasive grit (PAG) for managing weeds, and (ii) fabrication of a four-row implement that uses PAG to manage weeds (PAGMan). PAG performs well for in-row weed control in corn, but crop safety in soybean is unknown. Consequently, we examined responses to abrasion by corn-cob grit of soybean seedlings at VE, VC, VU, V1, V2, and combinations of these growth stages in both greenhouse and field settings. Seedling leaf areas and dry weights in greenhouse experiments were reduced by treatments that included abrasion at VC, with the primary effect expressed through reductions in the size of the unifoliate leaf. In the field, soybean stand also was reduced by grit applications at VC, especially if followed by a second application at VU or V1. However, soybean yield was not reduced by grit applied at any soybean stage of growth. End-of-season weed dry weights did not differ from hand-weeded checks and did not impact soybean yields. Thus, abrasive grit for in-row weed control can be applied at least twice at VE through V2 growth stages without lowering soybean yield, but applications at VC probably should be avoided. The second development, PAGMan, is an implement that was designed, constructed, and fine-tuned at the Agricultural and Biosystems Engineering Department at South Dakota State University during winter through summer 2012. It is tractor-mounted with a PTO-driven air compressor that delivers PAG at adjustable pressures through four pairs of nozzles aimed at either side of the bases of crop rows. The abraded swath resulting from each nozzle is about 5 to 10 cm wide, which creates a 10 to 20 cm-wide band of shredded weed seedlings centered on the crop row. At typical implement settings, PAGMan delivers about 84 ± 5.2 g per sec of grit. At the slowest conceivable operational speed of 1 m per second, this rate equates to 275 kg grit per hectare. Two to three abrasion events are needed for season-long control of annual weeds; thus, 500 to 1000 kg per hectare of grit may be required. Much additional testing of PAGMan is necessary to verify its utility.