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Soil sampling requirements in Delaware

Soil sampling requirements in Delaware

State rules: Delaware Code, Title 3, Chapter 22 (Nutrient Management). State guidance: Delaware Nutrient Management Program, Delaware Conservation Practice Standard: Soil Sampling and Analysis and University of Delaware Cooperative Extension, Delaware Soil Testing Program.

Soil sampling in Delaware: frequency, area, depth and cores

How often do you need to soil sample in Delaware?

How many acres can one soil sample cover in Delaware?

How deep should soil samples be taken in Delaware?

How many cores go into one soil sample in Delaware?

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

Delaware Nutrient Management Program, Delaware Conservation Practice Standard: Soil Sampling and Analysis: A uniform 100-acre field needs at least 3 composite samples of no more than 40 acres each, and at least 45 cores in all, 15 per sample.

Samples and cores for any field size

Soil sampling rules in Delaware, with the exact wording of each source
Country / region Purpose / programme Time / frequency Area per sample Method Depth Cores Status and source
United States
DelawareUnited StatesDelaware only. Other states set their own rules.Soil test results in the nutrient management planDelaware Nutrient Management Program (Delaware Nutrient Management Commission)Not specifiedNot specifiedNot specifiedNot specifiedNot specifiedConditionalDelaware Code Title 3 (PDF), Chapter 22
Who it applies to, the exact wording and every source
Who it applies to
Animal feeding operations over 8 animal units, and anyone who owns, leases or controls more than 10 acres where nutrients are applied. Their nutrient management plan must include the results of applicable soil analyses, and records of implementation must include soil test results. The plan is updated at least every 3 years or on significant changes in operations; the Act sets no soil sampling interval.
Outside the rule
Nutrient handlers applying to turf of more than 1/4 acre but less than 10 acres need no plan, but stay subject to the limits in the title and the regulations. Animal feeding operations that use no other nutrients and do not land apply their animal waste may substitute an animal waste management plan. County, municipal and industrial facilities permitted by DNREC under the land treatment of wastes rules are exempt from the chapter.
Laboratory and analysis
Phosphorus is read as the Mehlich 3 fertility index value (FIV). Fields above FIV 499 need a phosphorus site index assessment before phosphorus is applied.
In force from
Under review
Legal text
Delaware Code, Title 3, Chapter 22 (Nutrient Management), § 2247 (nutrient management plans) and § 2202 (definitions)

The wording in the source

Who it applies to

  • All animal feeding operations with greater than 8 animal units or any person who owns, leases or otherwise controls property totaling more than 10 acres upon which nutrients are applied shall develop and implement a nutrient management plan in accordance with the schedule outlined in this section.

    § 2247(a)

  • Results of applicable soil, plant, water, manure, or organic by-products analyses.

    § 2247(a)(4), plan contents

  • Soil test results and recommended nutrient application rates;

    § 2247(d)(1), records of implementation

  • Nutrient management plans shall be updated a minimum of every 3 years or upon significant alterations in facility operations, or upon a 25% or greater increase in facility operations.

    § 2247(e)

Outside the rule

  • Nutrient handlers who apply nutrients to turf totaling more than ¼ acres (10,890 square feet) but less than 10 acres shall not be required to have a nutrient management plan but are subject to limits outlined in this title and the Commission’s regulations.

    § 2247(a)

  • In the case of animal feeding operations where no other nutrients are used for farming and the animal waste is not land-applied, the operator of the facility may substitute an animal waste management plan for a nutrient management plan.

    § 2247(j)

  • County, municipal and industrial facilities discharging solid or liquid waste and permitted by the Department of Natural Resources and Environmental Control under The Guidance and Regulations Governing the Land Treatment of Wastes shall be exempt from the provisions of this chapter.

    § 2247(l)

Laboratory and analysis

  • “Fertility index value” or “FIV” is equivalent to the measured Mehlich 3 soil test phosphorus concentration in parts per million

    § 2202(13)

  • All fields with FIV exceeding 499 must have a PSI assessment prior to phosphorus application. Results of the PSI are valid for a term not to exceed 3 years.

    § 2247(b)(2)

Sources

Sources re-checked every two months, last update October 2026. Reviewed by GeoPard editorial team.
DelawareUnited StatesDelaware only. Other states set their own rules.Soil sampling and analysis for nutrient management plansDelaware Nutrient Management Program, Delaware Conservation Practice Standard: Soil Sampling and AnalysisNot specifiedNo more than 40 acres per sampleSmaller areas that differ in color, texture, drainage class, management or productivity are sampled separately.Approximately 8 inchesA minimum of 15 to 25 cores per sampleOfficial guidanceDelaware Department of Agriculture, Practice Standard Soil Sampling and Analysis (PDF)
Who it applies to, the exact wording and every source
Who it applies to
Practice standard of the Delaware Nutrient Management Program, applying among other cases as part of any nutrient management plan. Published as a program standard, not as law.
Laboratory and analysis
Laboratories enrolled each year in a proficiency assessment program such as NAPT or ALP. Results in ppm or University of Delaware Fertility Index Value.
In force from
Under review
Legal text
Delaware Department of Agriculture, Delaware Conservation Practice Standard, Soil Sampling and Analysis (October 2016)

The wording in the source

Area per sample

  • A soil sample should represent an area no larger than 40 acres

    Considerations

Method

  • Smaller areas that seem different in color, texture, drainage class, management practices, and/or productivity should be sampled separately.

    Considerations

Depth

  • a minimum of 15 to 25 soil cores taken approximately eight inches deep.

    Considerations

Cores

  • a minimum of 15 to 25 soil cores taken approximately eight inches deep.

    Considerations

Laboratory and analysis

  • Soils should be tested only by labs that have enrolled as participants of a proficiency assessment program (such as North American Proficiency Testing (NAPT) or Agriculture Laboratory Proficiency (ALP) each year.

    Criteria, Proficiency Testing

  • All lab results should be reported in parts per million (ppm) or University of Delaware, Fertility Index Value (UD-FIV)

    Criteria, Proficiency Testing

Sources

Sources re-checked every two months, last update October 2026. Reviewed by GeoPard editorial team.
DelawareUnited StatesDelaware only. Other states set their own rules.Soil sampling for commercial crop productionUniversity of Delaware Cooperative Extension, Delaware Soil Testing Program
  • Repeat Annual crops: every year, or every 2 to 3 years where fertility is very high
  • Repeat Perennial crops such as alfalfa or pasture: before seeding, then at least every 3 years
In general, 40 acres at most per sampleOne soil type or condition per sample. Separate samples for different soils or management histories. Avoid wet spots, dead furrows, stockpile sites and old fertilizer bands.Plow depth, usually 6 to 9 inches. No-till and reduced tillage also 6 to 9 inches.15 to 25 cores per sampleOfficial guidanceUniversity of Delaware Soil Testing Program, General Information
Who it applies to, the exact wording and every source
Who it applies to
Advice for commercial crop production in Delaware from University of Delaware Cooperative Extension. Not law.
In force from
Under review
Legal text
University of Delaware Soil Testing Program, How to Take a Soil Sample for Commercial Crop Production

The wording in the source

Timing

  • Annual Crops: Testing annually is generally recommended. If fertility levels are very high, sampling every 2 to 3 years is adequate.

    When and How Often to Test

  • Perennial Crops (e.g., Alfalfa/Pasture): Test prior to seeding and at least every 3 years thereafter.

    When and How Often to Test

Area per sample

Method

  • Separate Samples: Areas with different soil types (e.g., Sandy Knoll vs. Black Soil) or different management histories (e.g., Corn field vs. Soybean field) must be sampled separately.

    Sampling Guidelines

  • A good soil sample should represent only one soil type or condition.

    Selecting the Sampling Area

Depth

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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