Soil Sampling

Topic # 2036

Mr. Christensen

A little Review

O Horizon (Organic)A Horizon (Topsoil)

E Horizon (Subsurface)

B (Subsoil)C (Substratum)R (Bedrock)

Michigan State University http://www.geo.msu.edu/geo333/soils.html

Soil Map Montcalm County

Montcalm County, Michigan Fairplains Sheet 51 Scale 1:20,000

Mm McBride Sandy LoamCa Carlisle

Why Sample Soils?

• Determine plant nutrient availability• Diagnostic tool for problem soils• Soils in Michigan vary greatly and change

overtime due to crop removal• Tests include: pH, electrical conductivity

(EC), organic matter, nitrate-nitrogen, phosphorus, potassium and other micronutrients

What is pH?

• pH is a measure of the acidity or alkalinity in the soil.

• pH is measured by the number of hydrogen ions present in the soil solution

• The pH scale goes from 0 (acid) to 14 (alkaline) with 7 as neutral

What is pH?• pH uses a logarithmic scale for the hydrogen ion

concentration

pH 6.0 is 10-times more acidic than pH 7.0

pH 5.0 is 100-times more acidic than pH 7.0

MostAcid

Blueberries

4.0-5.1

Oats

5.0-7.0

Corn

5.5-7.5

Alfalfa

6.3-7.8

Cranberries

4.2-5.0

Potatoes

5.2-6.5

Grasses

5.5-7.5

Beans

6.0-7.5

Azalea

Magnolia >5.5

Trefoil

5.5-7.0

Sugar Beets

6.0-7.5

Strawberries

5.0-6.5

Wheat

5.5-7.0

Soybeans

6.0-7.0

Least Acid

pH Tolerance

Why is pH Important?

• Soil pH influences the availability of nutrients-a pH of 6-7 is generally favorable for plants, however some plants prefer more acid (blueberries, azaleas (4.5-5.2))or alkaline soils (monkshood, Lady fingers)

• Impacts the type and population of microorganisms (pH 6.6-7.3 is favorable for microbial activity that promotes nitrogen, sulfur and phosphorus availability.)

Ohio State University http://hcs.osu.edu/hcs412/sos6.htm

Alfalfa at Low pHPoor growthLack of Symbiotic bacteriaFor nitrogen fixation

Why is pH Important?

• Mobility of heavy metals increases with acidity and can leach into streams or aquifers

• Corrosive to steel under high alkalinity or highly acid soils, concrete is corroded at pH 5.5 or lower

• Impacts soil applied herbicide effectiveness

Future Garden http://futuregarden.com/nutrition/pH_availability_chart.gif

Why Does pH and Fertility Change?

• Climate

• Weather

• Soil Mineralogy (sulfur in the soils)

• Breakdown of organic matter

• Plants remove nutrients

• Anhydrous ammonia breakdown

Crop Nutrient Removal

Crop Yield Nutrients removed in harvest

bu/ton/acre N P2O5 K2OAlfalfa hay 6 ton 270 60 270Corn, grain 150 bu 135 64 42Corn, stover 4.5 ton 101 36 144Soybeans 50 bu 188 44 66Cucumbers 10 ton 20 12 36Celery 30 ton 150 60 480Wheat, grain 60 bu 75 38 23Wheat, straw 2.5 ton 30 8 53

How Do We Control pH?

• Soil acidity pH can be raised by adding lime materials (calcium oxide CaO)which neutralize the H+ ions and replacing them with calcium (Ca++)/magnesium (Mg++)

• Types of Limestone—burnt/hydrated (fast reacting), Calcic/Dolomitic (slower but less expensive), by-products (slag, paper mills,wood ash), Shell meal and Marl

• Lower pH using Aluminum Sulfate or Sulfur

University of Minnesota http://www.soils.umn.edu/academics/classes/soil2125/doc/s11chp6.htm

Soil Sampling Equipment

Colorado State University http://www.colostate.edu/Depts/SoilCrop/extension/Newsletters/2002/Beans/planning.html

Soil ProbeSoil BorerBucketShovel/spadeSoil mapSpecimen Bag/Box

Soil Sampling

• Select/group Areas based on:

Soil type

Past management/cropping history

Topography

Field Size

10-15 acres per sample

Soil Sampling

• 20 cores per sample (1lb sample is 1 part in 2 million “acre furrow slice”)

• Consistent depth (plow depth 8 inches, minimum tillage include sample from the top 2 inches)

• timing pH, P and K every three years Nitrogen varies greatly, what are your nitrogen

credits? A pre-side dress test may be required to determine needs.

Soil Sampling Patterns

University of Montana http://www.montana.edu/wwwpb/pubs/mt8602.html

Zig-Zag Pattern

Soil Laboratory Report

A. Aerial Photo of 67 acre fieldB. Management zonesC. 2 acre field grids

Lime Application MapBased on soil test results in each zone

Cooperative Extension Service The University of Georgia http://www.ces.ugs.edu/pubcd/B1208.htm

Grid Sampling

Linco Equipment Company-http://www.linco.com/atrssu.htm

Agro Company http://www.gpsagro.dk/index_uk.htm

12 Satellite accuracy 2 meters24 Satellite accuracy 10 cmUp to 7,250 samples a acreOn the go sampling is being tested

Spreading Lime

Rolling Red Prairie Kennel http://www.frenchbrittany.hypermart.net/pics14-08

Successful Farming http://www.agriculture.com/sfonline/sf/1997/january/precisn/1.html

Apply up to 6 tons of lime per year, retest and reapply if necessary the next year

Average pH of 6.0 for field Average pH of 6.5 for field

Potassium application mapPhosphorus application map

Kansas State University http://www.oznet.ksu.edu/pr_prcag/sandpivot.shtml

CEC Exchange capacity map at 7250 samples/acreOrganic soils>Clay>sands

Soil Doctor Systems http://www.soildoctor.com/grid.html