How soil sampling types work – FarmQA

Composite and zone sampling is available to selected accounts. If you don't see these features, contact your FarmQA representative.

FarmQA supports three ways of sampling a field: grid, composite, and zone. They differ in one thing that changes everything downstream — how many physical collection points go into a single bag sent to the lab. This article explains that difference and the terms that go with it. It has no steps; the how-to articles linked throughout are where you act on each piece.

Grid sampling works the way it always has. Composite and zone sampling are new, and they exist because a bag is not the same thing as a point.

Points, bags, and sample ids

A sample point is a GPS location on the map where a core is pulled. A point is a location, not a bag.

A bag is what physically goes to the lab. One bag produces one lab result.

A sample id is the identifier you write on the bag or scan from its barcode. One sample id means one bag, one lab result, and one soil sample record in FarmQA. The web app calls this the Reference number; the mobile app calls it the sample id. This article uses Sample ID for both.

In grid sampling those three line up one-to-one, so the distinction never comes up. In composite and zone sampling, many points feed one bag, and the Sample ID is what holds the bag's identity.

The three sampling types

Sampling type	In the field	What reaches the lab	Sample IDs
Grid	One core per point	One bag per point	One per point
Composite	Cores pulled from across the whole field, mixed together	One bag for the whole field	One for the whole task
Zone	Cores pulled within each zone, mixed per zone	One bag per zone	One per zone

Composite is a mixing method: everything collected across the field goes into one bag, and you get one result for the field. There are no zones.

Zone is a strategy: the field is divided into areas and a separate composite sample is taken inside each one. Each zone produces its own bag and its own result. Zone sampling uses composite sampling within each zone — they are related but not the same thing.

Mechanically the two are the same shape. A composite task is a zone task with exactly one group, which the mobile app names Whole field.

Sampling type is set on the task type

The sampling type belongs to the task type, not to the individual task. When an administrator creates a soil sampling task type, they set its Soil sample type to Grid, Composite, or Zone, and every task created from that type inherits it.

The sampling type is fixed when the task type is saved and can't be changed afterward. That means your existing soil sampling task types are all grid and stay grid — there's nothing to convert. To sample by composite or zone, an administrator creates new task types alongside the ones you already have.

At task creation the sampling type appears as read-only. You choose it by choosing the task type, and it can't be changed once the task exists — which keeps collection behavior from shifting partway through a sampling run.

Zones come from a management zone layer

A zone sampling task doesn't invent its zones. You select an existing management zone layer for the field, and that layer's zones become the task's zones, with their names carried over.

Because the zones are already drawn, you don't assign points to them. You place points on the map and FarmQA attributes each one to whichever zone contains it. Where zones overlap, the first match wins.

Two consequences worth knowing before you plan a sampling run:

A field with no management zone layers can't be used for a zone sampling task. Build the zone map first.
The sampling plan on a task stops being editable once the task is no longer new — that is, once it's in progress or complete. In practice collection is what triggers that. On mobile, the task's zone layer is fixed for the whole collection session.

Collection locations become markers

Every location a technician records is stored as a geo marker, so the physical collection pattern stays on the map after the samples go to the lab.

The marker type is set on the task, and FarmQA only offers marker types whose type is Soil sample location. At least one has to exist in your account — without one, a soil sampling task can't be created at all.

A composite or zone sample carries many locations, so expect several markers per sample. New locations create new markers; a location that resolves to a marker already on the field reuses it instead. New markers are named from the sample's reference number — the first takes the reference number on its own, and any after it get a counter appended, starting at (1).

In the Samples list on the Soil page, a composite or zone sample's row shows those marker names. Expand the row to see each location individually, with its marker name, marker type, latitude, and longitude.

What a partly sampled task means

You don't have to sample every zone before submitting. A zone you couldn't reach — no cores pulled, no Sample ID entered — raises a warning and asks you to confirm, but it doesn't stop the submission. That zone produces no soil sample record and doesn't reach the lab. It's simply absent from the results, and you can sample it later on a new task.

Two things do block submission, and both have to be resolved before the task will go:

A zone with cores but no Sample ID. If cores were collected against a zone, that zone needs its Sample ID before the task can be submitted.
A duplicate Sample ID. Every Sample ID in a task must be unique.

What the lab receives

Lab files are built per Sample ID, not per point. One Sample ID produces one barcode, one MODUS entry, and one line in the PDF report. A composite task with forty collection points still sends one bag and one line; a zone task with four zones sends four.

Physical collection locations aren't included in lab files at all. They stay in FarmQA, attached to the sample record, where they're used for mapping and export.

Both submission paths work for all three sampling types: automatic submission when the task is completed, and manual export from the completed task. Automatic submission depends on the lab profile having it enabled, not on the sampling type.

What results look like when they come back

A composite sample carries one set of measurements and many locations. A zone sample carries one set of measurements, many locations, and the zone it belongs to. That shape shows up in a few places:

Importing results. Your existing barcode-match import profiles work as they are. Rows match to sample records by Sample ID, and a file carrying two depths for the same Sample ID creates a record per depth, the same as it always has.
Viewing samples. Every collection location for a sample appears on the mini map, and zone samples show the management zone they came from.
Shapefile export. A composite sample exports as a multipoint. A zone sample exports as two layers in the same zip file: the main layer carrying its collection locations, and a second _zones layer carrying the zone polygon.
The public API. Composite and zone sample results are available through the same endpoints as grid results. Every sample carries a locations array alongside the original single-location fields.
Formulas and nutrient maps. A composite sample is evaluated across the whole field shape; a zone sample is evaluated on its zone shape. Individual collection points aren't used. The sample type filter is a multi-select that defaults to all three, so a single run can include grid, composite, and zone samples together.