Variable Rate Sprayers [Professional]

Introduction

To achieve a more precise, ecological and economical pesticide application process, it is important to focus on crop parameters and field variability instead solely on disease occurrence. In fields with different soil quality, crops and water availability the amount of spray needed varies as well. For example, areas with a reduced cop growth need a lower amount of spray liquid to cover the crop surface, a locally adapted variable-rate spraying strategy in these areas will reduce the amount of fungicidal liquids that reach the ground and would be left unused.^[1]

Variable Rate systems can be used on sprayers and run either by real-time sensing system or from pre-prepared prescription maps. In both cases the principle is to adjust application rates based on soil sampling results or agrochemical inputs based on crop qualities, such as vegetation maps. What is required is a GNSS receiver and a VR controller.^[2]

Figure 1: VRA spraying system using modulated spraying-nozzle control (MSNC) technology. The controller can control individual nozzles or the entire boom.^[4]

In Real-time detection Variable Rate sprayers, sensors automatically sense weeds and activate specific nozzles only when necessary. For map-based weed control VRA systems, some form of “task computer” is required to provide a signal indicating the target rate for the current location. Also a system for physically changing the application rate to match the current prescribed rate is required.

Figure 2: Smart Nozzles with GPS technology^[3]

Modulated spraying-nozzle control (MSNC) systems permit VRA with spray drift control under a wide range of operating conditions. High-speed valves, are used to regulate the amount of time that spray is delivered from conventional nozzles. The systems offer the ability to change flow rate and droplet size distribution on the go. It operates under direction of a microprocessor and an application controller that responds to signals from flow and pressure sensors.

The basic concept behind MSNC spraying is to operate each nozzle at full design pressure and flow during periods when a flow control valve is open. The key is to vary the amount of time that the valve stays open to produce variation in the flow rate without changing droplet size distribution or spray pattern. A fast-acting, electrical solenoid-controlled nozzle assembly is mounted directly to a conventional nozzle assembly.

Figure 3: Fasting-acting, electrical solenoid-controlled nozzle assembly.^[4]

Related Smart Farming Technology Products

Altek Individual Nozzle Control^[3]

Using GPS technology, altek’s Smart Nozzle system allows the individual and independent control of each nozzle on the spray line, effectively making each nozzle a section. The Smart Nozzle technology gives growers retro fit access to high grade precision in crop protection.

Figure 4. Alteks Variable Rate Spraying system controller and nozzles

Related Scientific Papers

Precision variable rate spray is one of the research hotspots in the field of modern agriculture spraying applications research due to how heavy are the environmental imapcts of herbicides and fungicides. Variable rate spraying allows growers to apply adjusted volume rate of pesticides to the target and saves more than 50-75% of pesticides, improves the utilization rate (over 55%), control efficiency and significantly reduce environmental pollution caused by the pesticide application.^[2]

Performance Evaluation of a newly developed Variable-Rate Sprayer for nursery liner applications^[5]

In this paper, Jeon et al. performed spray tests in olive, apple, and pear orchards showed that the sprayer reduced chemical use by 28% to 72% compared to a conventional sprayer.

Figure 1. Main components of the experimental variable‐rate sprayer for liner applications from Jeons et al.’s field tests: 1 = ultrasonic sensor, 2 =spray nozzle with PWM sole‐ noid valve, 3 = spray delivery system, 4 = data logger (used only for field tests), and 5 = microcontroller.

Methane and Nitrous Oxide Mitigation in Agriculture^[6]

Bates et al. (2009) identified an abatement potential with VRNA if 5% reduction in the baseline greenhouse gas emissions rate that is assigned to mineral fertiliser application without yield impact. Also Tekin (2010) estimated that VRNA can increase wheat production between 1% and 10% offering savings in nitrogen fertilisation between 4% and 37%. He also made an economic analysis using the prices of the VR equipment, the fertilisers and the price of the wheat seed and found out that the investment cost over a 5-year depreciation period would vary between 11.45€ and 115.39€ for a 50 ha and 500 ha farm size respectively. In another project of HydroSense (2013) a net benefit of 113€/ha/year was identified. Kuang et al., (2014) found that VR approach in Danish spring barley can be compared to the traditional approach. Fuel saving are ranged from 0.044€-0.062€/ha and operator labor savings from 0.035€-0.06€/ha. Yearly costs are fixed and around 2.645€.