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Soil sampling requirements in North Dakota

Soil sampling requirements in North Dakota

State guidance: NDSU Extension sampling advice.

Soil sampling in North Dakota: frequency, area, depth and cores

When in the year should soil be sampled in North Dakota?

How many acres can one soil sample cover in North Dakota?

  • NDSU Extension sampling advice Official guidance Where grid sampling is used: one sample per acre (0.40 ha). Coarser grids, such as one sample per 2.5 acres, are inadequate in North Dakota. The guide sets no area for zone samples.

How deep should soil samples be taken in North Dakota?

  • NDSU Extension sampling advice Official guidance 0 to 6 inches (0 to 15.24 cm) for pH, P, K, Zn, Cu, Mn. 0 to 2 feet (0 to 60.96 cm) for nitrate-N and chloride, best split at 6 inches. No-till: 0 to 2 inches (0 to 5.08 cm) separately from 2 to 6 inches.

How many cores go into one soil sample in North Dakota?

How many soil samples does a 100-acre field need in North Dakota?

NDSU Extension sampling advice: A uniform 100-acre field needs at least 100 composite samples of no more than 1 acres each, and at least 800 cores in all, 8 per sample.

Samples and cores for any field size

Soil sampling rules in North Dakota, with the exact wording of each source
Country / region Purpose / programme Time / frequency Area per sample Method Depth Cores Status and source
United States
North DakotaUnited StatesNorth Dakota only. Other states set their own rules.Soil sampling for fertilizer recommendations, including nitrateNDSU Extension sampling advice
  • Season Nitrate samples may be taken right after any grain harvest. Sample for K at the same time each year.
Where grid sampling is used: one sample per acre (0.40 ha). Coarser grids, such as one sample per 2.5 acres, are inadequate in North Dakota. The guide sets no area for zone samples.Zone sampling, with zones built from at least two tools such as crop canopy imagery, soil EC sensors, multiyear yield maps and elevation. A systematic unaligned grid only in areas with large manure applications or fields with large P and K buildup applications.0 to 6 inches (0 to 15.24 cm) for pH, P, K, Zn, Cu, Mn. 0 to 2 feet (0 to 60.96 cm) for nitrate-N and chloride, best split at 6 inches. No-till: 0 to 2 inches (0 to 5.08 cm) separately from 2 to 6 inches.Eight to 10 cores at random within each zoneOfficial guidanceNDSU Extension, SF990 Soil Sampling as a Basis for Fertilizer Application
Who it applies to, the exact wording and every source
Who it applies to
Advice for North Dakota fields from North Dakota State University Extension. Not law.
In force from
Under review
Legal text
NDSU Extension, Soil Sampling as a Basis for Fertilizer Application (SF990, revised September 2023)

The wording in the source

Timing

Area per sample

Method

  • Grid sampling is recommended in North Dakota only in areas with large manure applications or in fields that have received large amounts of buildup P and K fertilizers.

    SF990, Sampling for Within-field Soil Test Values

  • Zones should be developed using at least two tools (Franzen et al., 2011).

    SF990, Zone Sampling

  • Aerial imagery from piloted aircraft or drones … satellite imagery of growing crops … soil electrical conductivity sensors … multiyear yield maps … topography developed from subinch accuracy GPS elevation … may be used to help develop zones for use in soil sampling.

    SF990, Zone Sampling

  • The pattern of grid sampling should be a systematic, unaligned grid as illustrated in Figure 7.

    SF990, Sampling for Within-field Soil Test Values

Depth

  • For soil pH, P, K, Zn, copper (Cu) and manganese (Mn), sampling the 0- to 6-inch depth is required because that is the depth of sampling related to crop response in this region.

    SF990, Depth of Sampling, Nutrients

  • For soil nitrate-N and chloride, a 0- to 2-foot core is required. Instead of analyzing just one 0- to 2-foot core, dividing the core into a 0- to 6-inch core and a 6- to 24-inch core, and analyzing each one separately would be instructive.

    SF990, Depth of Sampling, Nutrients

  • Therefore, in fields under no-till systems, the 0- to 2-inch depth should be separated and analyzed separately for soil pH, P and K in addition to analyzing soil at the 2- to 6-inch depth.

    SF990, Tillage System

Cores

Sources

Sources re-checked every two months, last update October 2026. Reviewed by GeoPard editorial team.

United States: federal rules and every other state

Soil sampling regulations in every country

Report an outdated requirement: info@geopard.tech

Plan the points to the rule that applies

Set the area per sample, the cores and the depth your rule asks for. GeoPard places the points on a grid or by zone, routes the walk, prints the labels and takes the plan to the field on a phone.

Create a sampling plan See the Soil Sampling Planner

A planning reference built from official sources, not legal advice. Rules apply by jurisdiction, nutrient, land use and programme: check the current official text and your laboratory’s instructions before fieldwork.

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