Composite sampling by zone protocol

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The goal of this protocol is to organize the process to create zones for a particular field within a farm and use them to plan and carry out field sampling by zones.

  • Region:South africa
  • Contributors: Oasis Consulting, Avison Fertilizers.

Create management zones

The first step is to create your management/sampling zones, based on your Productivity maps. Some considerations are: 

  • Number of zones: having too many types of zones on the same field might make the field work more complicated, for instance, 3 to 5 zones could be manageable.
  • Zone limits: when going through the field visit, take into account and analyze where a zone transitions into a different zone, and whether it's a gradual or sudden process.
  • Historic crop behavior in each different productivity zone.
  • Operational conditions that may impact in your zone management (e.g.: if there's machinery available which can manage microzones)
  • Other aspects, such as topography, expected season weather, etc.


This guide shows the steps for carrying it out.


The figure below is an example of management zones created, based on a productivity map

Productivity map Management Zones
How to create management zones based on PM 11.JPG How to create management zones based on PM 10.JPG


This layer will be used to plan your sampling, as shown in the next step.


Define Grid sampling points

Next, define a grid of sampling points, following these instructions.

  1. Create your points layer, where you will generate your sampling locations. Make sure you create your sampling layer with a structure "Field sampling", this way, later on you will be able to import them into 360.
  2. Create a grid of sampling points using the grid tool for your entire field. Make sure you number them to simplify locating them in the field.
  3. To print out a map with the zones and points to use as field support, use the print tool. Also, in order to print a full screen map, use the option Save map only.
    Zoning and sampling in South Africa protocol 2.jpg

Take composite samples by zone in the field, then send them to the lab

It's now time to go to the field and take your samples.

You can take them using a GPS device, following these steps:

  1. Prepare your GPS for your field visit
    1. Connect your GPS to GeoAgro GIS: you need this to transfer your grid points from the previous step to your GPS device and use them in your sampling. These articles will help you with this:
    2. Upload your grid sampling points to your GPS device: you can now send the grid points for your management zones to your GPS device, and take them to the field.
  2. Go to the field and Use the GPS points in your GPS device to go to the predefined locations'
  3. Take your samples in each location, combining samples within each zone into a single composite sample
  4. Send your samples to the lab, numbering them to correspond each zone


Receive lab results and specify recommendations by zone

In this step, lab results per sample are received:

Lab results.png


Based on the lab results, the agronomist analyzes the nutrient and chemical corrections requirements by zone, and available products in the region. As a result, a specific recommendation by field/zone is determined, as illustrated int the following figure.

Fertilizer reqs.png

This will be used in the creation of prescription maps to send to the application machine.