Soil sampling requirements in Missouri

Q: How often do you need to soil sample in Missouri?

Missouri DNR CAFO Nutrient Management Technical Standard (official guidance): Result valid: Re-sample before manure application when the soil test is more than five years old, or the phosphate surplus since the last test exceeds 500 lb/acre. University of Missouri Extension soil sampling advice (official guidance): Every three to five years, at the same time of year as the last sample.

Q: When in the year should soil be sampled in Missouri?

University of Missouri Extension soil sampling advice (official guidance): When the field is idle: fall and winter after harvest for forages and spring crops; summer for winter wheat and fall-seeded crops. At least three months after phosphorus fertilizer, lime or manure.

Q: How many acres can one soil sample cover in Missouri?

Missouri DNR CAFO Nutrient Management Technical Standard (official guidance): Approximately 20 acres or less per sample. Grid alternative: cells under 3 acres. University of Missouri Extension soil sampling advice (official guidance): Sampling areas typically no more than 20 acres. Grid sampling: typically one sample per 2.5 acres or less.

Q: How deep should soil samples be taken in Missouri?

Missouri DNR CAFO Nutrient Management Technical Standard (official guidance): 6 to 8 inches. University of Missouri Extension soil sampling advice (official guidance): 6 to 7 inches for most objectives. Long-term no-till: a separate 0 to 2 inch sample for surface pH.

Q: How many cores go into one soil sample in Missouri?

Missouri DNR CAFO Nutrient Management Technical Standard (official guidance): At least 15 representative cores per sample, more on pastures or where phosphorus was banded. Grid: at least 10 cores within 15 feet of the grid point. University of Missouri Extension soil sampling advice (official guidance): 10 to 20 cores. 15 to 20 with manure, banded fertilizer or other variation; 10 to 15 on uniform, broadcast-fertilized fields. 30 cores in a set pattern where injection bands are known.

Q: How many soil samples does a 100-acre field need in Missouri?

Under Missouri DNR CAFO Nutrient Management Technical Standard: A uniform 100-acre field needs at least 5 composite samples of no more than 20 acres each, and at least 75 cores in all, 15 per sample.

State guidance: Missouri DNR CAFO Nutrient Management Technical Standard and University of Missouri Extension soil sampling advice.

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

How often do you need to soil sample in Missouri?

Missouri DNR CAFO Nutrient Management Technical Standard Official guidance Result valid: Re-sample before manure application when the soil test is more than five years old, or the phosphate surplus since the last test exceeds 500 lb/acre.
University of Missouri Extension soil sampling advice Official guidance Every three to five years, at the same time of year as the last sample.

When in the year should soil be sampled in Missouri?

University of Missouri Extension soil sampling advice Official guidance When the field is idle: fall and winter after harvest for forages and spring crops; summer for winter wheat and fall-seeded crops. At least three months after phosphorus fertilizer, lime or manure.

How many acres can one soil sample cover in Missouri?

Missouri DNR CAFO Nutrient Management Technical Standard Official guidance Approximately 20 acres or less per sample. Grid alternative: cells under 3 acres.
University of Missouri Extension soil sampling advice Official guidance Sampling areas typically no more than 20 acres. Grid sampling: typically one sample per 2.5 acres or less.

How deep should soil samples be taken in Missouri?

Missouri DNR CAFO Nutrient Management Technical Standard Official guidance 6 to 8 inches.
University of Missouri Extension soil sampling advice Official guidance 6 to 7 inches for most objectives. Long-term no-till: a separate 0 to 2 inch sample for surface pH.

How many cores go into one soil sample in Missouri?

Missouri DNR CAFO Nutrient Management Technical Standard Official guidance At least 15 representative cores per sample, more on pastures or where phosphorus was banded. Grid: at least 10 cores within 15 feet of the grid point.
University of Missouri Extension soil sampling advice Official guidance 10 to 20 cores. 15 to 20 with manure, banded fertilizer or other variation; 10 to 15 on uniform, broadcast-fertilized fields. 30 cores in a set pattern where injection bands are known.

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

Missouri DNR CAFO Nutrient Management Technical Standard: A uniform 100-acre field needs at least 5 composite samples of no more than 20 acres each, and at least 75 cores in all, 15 per sample.

Samples and cores for any field size

Soil sampling rules in Missouri, with the exact wording of each source
Country / region	Purpose / programme	Time / frequency	Area per sample	Method	Depth	Cores	Status and source
United States
MissouriUnited StatesMissouri only. Other states set their own rules.	Current soil test results for CAFO manure applicationMissouri DNR CAFO Nutrient Management Technical Standard	Result valid Re-sample before manure application when the soil test is more than five years old, or the phosphate surplus since the last test exceeds 500 lb/acre	Approximately 20 acres or less per sample. Grid alternative: cells under 3 acres.	Per MU Guides G9215 (pastures) and G9217 (row and hay crops). Georeferenced grid sampling is an alternative.	6 to 8 inches	At least 15 representative cores per sample, more on pastures or where phosphorus was banded. Grid: at least 10 cores within 15 feet of the grid point.	Official guidanceMissouri DNR CAFO Nutrient Management Technical Standard, March 4, 2009 (PDF, copy in the MU CAFO operator curriculum)
Who it applies to, the exact wording and every source Who it applies to Missouri DNR technical standard (March 4, 2009) for land application fields in the nutrient management plans of Class I CAFOs. Compliance is how a CAFO shows a precipitation-related discharge qualifies as agricultural stormwater. A department standard, not the regulation text. Laboratory and analysis A laboratory accredited by the Missouri Soil Testing Association, using University of Missouri Soil Testing Laboratory procedures. In force from Under review Legal text Missouri Concentrated Animal Feeding Operation Nutrient Management Technical Standard (Missouri DNR, March 4, 2009), Section III, A1(1) The wording in the source Timing Fields should be re-sampled before manure application when: NMTS, III A1(1)f The soil test is greater than five years old; or NMTS, III A1(1)f.i Phosphate surplus (actual applied phosphate minus actual removed phosphate) for the field has exceeded 500 lbs/acre since the last soil test; NMTS, III A1(1)f.ii Area per sample The average field area represented by a soil sample should be approximately 20 acres or less; NMTS, III A1(1)b Grid size should be less than three acres and at least 10 cores should be obtained from within 15 feet of the central grid point; NMTS, III A1(1)d Method MU Guides G9215 (for pastures) and G9217 (for row and hay crops); NMTS, III A1(1)a operations may elect to use a geo-referenced grid soil sampling method instead. NMTS, III A1(1)d Depth Soil sampling depth should be six to eight inches; NMTS, III A1(1)e Cores Each soil sample should be comprised of a well-mixed subsample derived from at least 15 representative cores from the sampled field area; more cores are recommended on pastures or where phosphorus has been band applied; NMTS, III A1(1)c Grid size should be less than three acres and at least 10 cores should be obtained from within 15 feet of the central grid point; NMTS, III A1(1)d Who it applies to The department’s CAFO regulations require the development and implementation of a field specific Nutrient Management Plan (NMP), meeting the criteria prescribed in 10 CSR 20-6.300(5)(A)-(I), at all Class I CAFOs. NMTS, I.A Authority and Purpose CAFOs will qualify for the Agriculture Stormwater Discharge exemption when they can demonstrate compliance with this NMTS at the time of a precipitation-related discharge from land application areas. NMTS, I.A Authority and Purpose Laboratory and analysis Soil samples should be analyzed at soil testing laboratories accredited by the Missouri Soil Testing Association NMTS, III A1(1)g using procedures recommended by the University of Missouri Soil Testing Laboratory. NMTS, III A1(1)g Sources Missouri DNR CAFO Nutrient Management Technical Standard, March 4, 2009 (PDF, copy in the MU CAFO operator curriculum) Guidance Sources re-checked every two months, last update October 2026. Reviewed by GeoPard editorial team.
MissouriUnited StatesMissouri only. Other states set their own rules.	Routine soil fertility sampling, hayfields and row cropsUniversity of Missouri Extension soil sampling advice	Repeat Every three to five years, at the same time of year as the last sample Season When the field is idle: fall and winter after harvest for forages and spring crops; summer for winter wheat and fall-seeded crops Wait At least three months after phosphorus fertilizer, lime or manure	Sampling areas typically no more than 20 acres. Grid sampling: typically one sample per 2.5 acres or less.	Divide fields into areas expected to be similar or managed alike; zigzag across the whole area. Grid sampling for variable rate, high-value fields or unknown history.	6 to 7 inches for most objectives. Long-term no-till: a separate 0 to 2 inch sample for surface pH.	10 to 20 cores. 15 to 20 with manure, banded fertilizer or other variation; 10 to 15 on uniform, broadcast-fertilized fields. 30 cores in a set pattern where injection bands are known.	Official guidanceMU Extension G9217, Soil Sampling Hayfields and Row Crops (PDF, CAFO operator curriculum copy)
Who it applies to, the exact wording and every source Who it applies to Advice for Missouri hayfields and row crops from University of Missouri Extension. Not law. Laboratory and analysis A laboratory accredited by the Missouri Soil Testing Association (MSTA). Field identifiers Label each sample with field and subfield names. In force from Under review Legal text MU Extension Guide G9217, Soil Sampling Hayfields and Row Crops The wording in the source Timing Sample your fields every three to five years. It is also recommended that you sample a field at the same time of year as your last sample because some soil test levels fluctuate during the year. G9217, When should I sample? It is best to wait at least three months after application of phosphorus fertilizer, lime or manure before taking a soil sample. G9217, When should I sample? The best time to collect soil samples is when the field is idle and enough time is available to plan fertilizer and lime applications for the next crop. G9217, When should I sample? Sampling after harvest in the fall and winter usually works best for forages and spring-seeded crops. G9217, When should I sample? For winter wheat and fall-seeded crops, sampling while the field is idle in the summer works well. G9217, When should I sample? Area per sample Typical sampling areas should not exceed 20 acres. G9217, How should I divide my fields? Grid soil sampling is a method of intensively sampling your field, typically obtaining a sample for every 2.5 acres or less. G9217, Should I grid sample my field? Method When creating a soil-sampling plan for fields and farms, the objective is to divide fields into areas that you expect to have similar characteristics or you are likely to manage similarly. G9217, How should I divide my fields? The best approach is to travel across the entire area to be sampled in a zigzag pattern randomly selecting spots to take a core (Figure 1). G9217, How to collect a soil sample This method of sampling is typically used when a farmer uses variable rate technology to apply fertilizers or lime. G9217, Should I grid sample my field? Grid sampling is most justified on high value and high yielding soils, particularly when you anticipate significant variations in soil test levels including low testing areas within a field. It can also be useful the first time you sample the soil in a field with an unknown history. G9217, Should I grid sample my field? Depth Sampling depth is 6 to 7 inches for most objectives. G9217, How to collect a soil sample A separate sample from 0 to 2 inches should be taken in long-term no-till fields to monitor surface pH. G9217, How to collect a soil sample Cores Your objective is to collect from 10 to 20 cores from the area to be sampled (Figure 1). G9217, How to collect a soil sample Take 15 to 20 cores on fields with a history of manure, banded fertilizer applications and other expected sources of variation. Fewer cores (10 to 15) are needed on uniform fields with a history of broadcast fertilization. G9217, How to collect a soil sample On fields where the location of injection bands for fertilizer or manure is known, the objective is to take 30 cores using the following method: G9217, Sampling Fields After Banded Fertilizer Applications Laboratory and analysis Be sure to use a lab that has been accredited by Missouri Soil Testing Association (MSTA). G9217, Submitting your soil samples Field identifiers Label the sample with field and subfield names. G9217, Submitting your soil samples Sources MU Extension G9217, Soil Sampling Hayfields and Row Crops (PDF, CAFO operator curriculum copy) Guidance 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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Soil sampling requirements in Missouri

Soil sampling requirements in Missouri

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

How often do you need to soil sample in Missouri?

When in the year should soil be sampled in Missouri?

How many acres can one soil sample cover in Missouri?

How deep should soil samples be taken in Missouri?

How many cores go into one soil sample in Missouri?

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

The wording in the source

Timing

Area per sample

Method

Depth

Cores

Who it applies to

Laboratory and analysis

Sources

The wording in the source

Timing

Area per sample

Method

Depth

Cores

Laboratory and analysis

Field identifiers

Sources

Plan the points to the rule that applies

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