Weedfinder: An Eco-Friendly Herbicide Sprayer, Year 2

Overview

Objectives/Goals Herbicide is wasted every year by farmers who spend 8 billion dollars to control weeds. Farmers lose money and harm the environment when using the full spray method in which everything is sprayed, including bare soil. To address this problem, I designed and built a device using electronic components and computer programming to detect and spray weeds selectively in vineyards. This eco-friendly system will lower farmers operating costs and reduce the volume of herbicide and water used. The engineering goals are to increase the efficiency of the device by 50% compared to last year#s prototype while maintaining a low cost of production for widespread use. Methods/Materials I built a circuit and programmed a microcontroller to turn on a solenoid valve to spray herbicides whenever the sensors detect a plant#s light reflectance (chlorophyll reflects infrared light). After testing several prototypes (year 2), I found out that frequency modulation helped detect weeds more efficiently. I also added a User Interface (UI) with a menu system and display to make testing easier, redesigned the lights and sensors for better brightness and alignment, and mounted the Weedfinder device on an ATV instead of using a handheld device. Results Trials in several vineyards showed that the average volume of herbicide and water saved was 67% compared to 38% in year 1. Conclusions/Discussion The design criteria and engineering goals are met in this project. The average volume of herbicide and water saved was 67% when using the Weedfinder. The new additions and changes in the device made it more efficient, and solved the problem of ambient light affecting the device#s light source (year 1). Because of the use of pulse-width modulation, the sunlight no longer overpowers the infrared lights, making it difficult to detect the weeds# reflectance. The Weedfinder can benefit farmers and the environment by lowering the amount of chemicals and water used by 67%. A future application will be to test the device with a propane weed flame burner.