Products > Agricultural

Variable Rate Controller

Precise and Cost Effective Spray Control

Developed by Silsoe Research Institute

A unique spray controller has been developed to automatically vary the volume of spray applied to a field according to a treatment map.  This allows sprays to be accurately targetted at specific areas or patches to control weeds, crop disease or pests.  It can also be used to control liquid fertliser applications according to soil and crop requirements.

The first variable rate controller commercialised in Europe to offer a wide range of control over spray volume output (up to 5:1 ratio), the PatchSpray controller has undergone extensive field testing and evaluation.  The system offers greatly improved precision in spraying to manage chemical inputs more effectively and minimise waste.
 

• Accurate, targetted treatment of crops and soils
• Reduces chemical usage
• Can be retrofitted to existing sprayers
• Reduces risk of environmental contamination
• Traceability of spray application

 

Introduction

The selective use of agrochemicals offers enormous potential economic and environmental benefits.  The objective is to use agrochemicals discriminately to improve yield production and quality yet minimise their use.  This demands greater control over the application process and the PatchSpray controller achieves this by automatically regulating the amount of spray applied.  This ensures the correct dose is delivered to the field area minimising waste and off target contamination.

Potential applications are:
 
Liquid fertilisers

To apply soil or foliar fertilisers selectively according to soil and crop requirements.

 

Herbicides

Many weeds of arable crops for example, such as, couch, blackgrass, thistles and cleavers, can be found growing in weedy patches.  The PatchSpray controller can target these weed patches using data from weed maps and avoid 'blanket' sprays to the whole filed.  Cost savings of around 50% have been shown to be possible.

 

Fungicides

Variable rates of fungicides can be applied using treatment maps based on, for example, leaf area density of the crop cover or other characteristics.

Nematicides/Insecticides
The PatchSpray controller can regulate application of soil applied nematicides according to a treatment map derived from soil sampling and can also apply variable rates of insecticides if required.



How It Works

The PatchSpray system is controlled from a treatment map stored in a computer in the tractor cab.  The position of the sprayer in the field is determined from the distance travelled down tramlines or from a satellite based Global Positioning System (GPS).  The sprayer can deliver a defined dose every 2 metres of travel.

The spray boom is fitted with two or more sets of nozzles with different orifice sizes and split into different sections (usually four).  The PatchSpray system then selects the appropriate combination of nozzles (controlled by pneumatic or solenoid valves) and line pressure to achieve the required dose for that area of the field as determined by the treatment map.

In this way the optimum spray quality, based on the droplet size distribution is maintained which is critical to achieve biological efficacy yet avoid unnecessary drift.

The PatchSpray controller is mounted on the sprayer itself.  In the tractor cab there is a separate control unit to allow the operator to select different nozzle combinations for fertiliser, herbicide or fungicide applications or operate the sprayer entirely in manual mode.  The characteristics of the spray nozzles are pre-programmed into the PatchSpray controller.
 
The system overcomes the inherent limitations of using only pressure control to vary the output from a single nozzle as this can adversely change the spray quality and particle size.  Such systems usually are limited to a flow rate variation of only + or - 20% of the nominal output - insufficient for most precision spray applications.

The PatchSpray system is applicable to precision farming (site specific) systems where variations in excess of + or - 75% of the average dose may be required in defined parts of the field.
The whole spraying system not only gives precise control over the spray volume applied but can also record operations.  This can form an integral part of the record keeping and management procedures required as part of farm quality assurance schemes and allow operators to comply with all regulatory legislation to protect waterways and the general environment as well as avoiding mis-application.  The technology, which is relatively low cost, can be produced as a retrofit kit for existing sprayers or built in as an integral part of new sprayers.

 

Licensed from BTG International Ltd.  Patent No. W098/37974

For further details please contact:

John Clayton
Micron Sprayers Ltd., Bromyard Industrial Estate,
Bromyard, Herefordshire HR7 4HS, U.K.
Tel: +44 (0)1885 482397
Fax: +44 (0)1885 483043
E-mail: john.clayton@micron.co.uk 

Professor Paul Miller
Silsoe Research Institute, Wrest Park, Silsoe
Bedfordshire MK45 4HS, U.K.
Tel: +44 (0)1525 860000
Fax: +44 (0)1525 860156

Specifications