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Title: Laboratory tests to assess optimal agricultural residue traits for an abrasive weed control system

item PEREZ-RUIZ, MANUEL - University Of Sevilla
item BRENES, ROCIO - University Of Sevilla
item RODRUIGES-LIZANA, ANTIONIO - University Of Sevilla
item URBANO, JOSE - University Of Sevilla
item SLAUGHTER, DAVID - University Of California
item Forcella, Frank

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/26/2016
Publication Date: 6/29/2016
Citation: Perez-Ruiz, M., Brenes, R., Rodruiges-Lizana, A., Urbano, J., Slaughter, D.C., Forcella, F. 2016. Laboratory tests to assess optimal agricultural residue traits for an abrasive weed control system. International Conference of Agricultural Engineering. June 26-29, 2016, Aarhus, Denmark.

Interpretive Summary: Weeds can be controlled selectively in crop rows through the application of abrasive grits under high pressure, using a process analogous to sand-blasting. Effective grits can be comprised of agricultural products, typically crop residues or animal wastes. However, the characteristics that make one grit better than others are not yet known. Consequently, the goal of this research project was to examine the physical characteristics and weed-killing properties of eight different agricultural grits compared to the standard, sand. The agricultural residues included crushed olive seed, walnut shell, maize cob, poultry manure, soybean seed, almond shell (two types) and grape seed. Various physical properties, such as “angle of repose,” which simulates the roundness of grit, did not correlate with the ability of grit to control weed seedlings. The most effective grit with consistent killing properties (80% control) was derived from walnut shells. Walnut shell grit is characterized by distinct and highly angular faces, which likely increase its ability to cut and shred small weed seedlings compared to other grits. This information is beneficial for engineers and weed scientists who seek alternatives to herbicides for the control on weeds in row crops.

Technical Abstract: One of the biggest challenges to organic agricultural production and herbicide resistant crops in industrialized countries today is the non-chemical control of weed plants. Studies of new tools and methods for weed control have been motivated by an increased consumer demand for organic produce and consumer and regulatory demands for a reduction in environmentally harmful herbicide use. The objective of this study is to assess different agricultural residues as gritty weed-abrading materials that are delivered through condensed-air machinery. This is a new weed control technology based on highly-directed air-propelled, innocuous, abrasive grit. Laboratory equipment was designed to calculate the angle of repose of seven different agricultural residues (crushed olive seed, walnut shell, maize cob, poultry manure, soybean seed, almond shell and grape seed). Color, digital, high-speed computer vision analysis of the motion and energy of the air-propelled particles was conducted. The high-speed video analysis determined the capability of each grit to damage a reference surface and kill weeds (species of Amaranthus, Centaurea, and Chenopodium) at different growth stages. A preliminary laboratory trial showed that walnut shell grit has great potential to damage/break the reference surface when it was propelled at 600, 700 and 800 kPa air pressure. Abrasive-weeding reduced final weed growth by 80% compared with the weedy control at early growth stages. Field research tests are needed in different cropping systems to improve the technical and economic efficiency of this novel system before on-farm adoption.