Tine rake optimization in a soil bin

Physical Weed Control Tool Assays: Tine rake optimization in a soil bin
Jordan Parks1 and Eric Gallandt2
1Graduate Research Assistant, and 2Professor, University of Maine

Interim report: February 10, 2021
Take-home points:

  1. Using a soil bin as a tool for physical weed control assays has shown to be promising in detecting differences in efficacy by adjusting tine angle.

  2. Soil conditions can be uniformly adjusted and tool settings can be accurately set for repeatability so research can be conducted efficiently in the soil bin.

  3. Artificial weeds may be a promising way to measure tool mechanisms and efficacy.

Organic farmers rely on the use of physical weed control (PWC) as a means to minimize crop loss and damage (Gallandt, 2014). Tool effectiveness can be effected by weed growth stage, species type, and soil conditions (Kurstjens & Perdok, 2000). Farmers face varying conditions and environments, which cannot be controlled, but the type of tool, tool angle, working depth, and speed can be adjusted. Furthermore, determining how to adjust tools has become an art by using past experiences in the field (Bowman, 2002), which takes valuable time from farmers. More research is needed to determine which combination of controllable factors will provide optimal weed control.

To determine optimal settings for PWC tools, we built a soil bin inside of a glasshouse to create controlled conditions. Tool angle, working depth, speed, and soil conditions can be adjusted and tested in different combinations. The Johnny’s Selected Seeds tine rake was used to test a range of five different angles to measure efficacy using artificial weeds (35 mm-long wooden golf tees).

Figure 1. A range of five different tool handle angles were tested in a soil bin. The tool tested was the Johnny’s Selected Seeds tine rake (a.). Tool carriage where working depth and tool angle is adjusted (b.). Soil bin sample area (c.). 35 mm-long wooden golf tees used as artificial weeds after a cultivation event (d.).


Figure 2. Johnny’s tine rake handle angle effect on efficacy using artificial weeds (35 mm-long wooden golf tees). Angles tested were 26.0°, 30.5°, 35.0°, 39.5°, and 44.0°. How to read this graph: The dependent variable is efficacy, which is what we are measuring and the independent variable is the tool handle angle, which is what we are testing. The fit line (in blue) is an equation of a line, calculated with statistics, to predict values based on the data collected. Based on the equation above, efficacy (Y), can be predicted with knowing the tool handle angle (X).

Next Steps
The next step is to choose the best angle for usability and efficacy, then test it with three different depths (10 mm, 20 mm, and 30 mm) and three different speeds (1.8 mph, 2.5 mph, and 3.1 mph). This way we can measure how efficacy changes with speed and depth at the optimal tool handle angle.

Literature Cited
Bowman, G. (2002). Steel in the Field: A Farmer’s Guide to Weed Management Tools. Sustainable Agriculture Network.

Gallandt, E. R. (2014). Weed Management in Organic Farming. In B. S. Chauhan & G. Mahajan (Eds.), (pp. 63-85). Springer Science+Business Media. https://doi.org/10.1007/978-1-4939-1019-9_4

Kurstjens, D. A. G., & Perdok, U. D. (2000). The selective soil covering mechanism of weed harrows on sandy soil. Soil and Tillage Research, 55(3-4), 193-206. https://doi.org/10.1016/S0167-1987(00)00128-8