Soil Testing Procedures Soil Testing Procedures for Biologically Based for Biologically Based SystemsSystems

Raymond C. WardRaymond C. Ward

Ward Laboratories, IncWard Laboratories, Inc

Kearney, NebraskaKearney, Nebraska

www.wardlab.comwww.wardlab.com

Soil Testing for No Till Soil Testing for No Till FarmersFarmers I have been interested in developing I have been interested in developing

soil tests that could be analyzed soil tests that could be analyzed quickly and at low cost that could let quickly and at low cost that could let the farmer know how well his the farmer know how well his operation was improving yield and operation was improving yield and soil health.soil health.

Researchers at the National Tilth Lab Researchers at the National Tilth Lab at Ames Iowa are developing a soil at Ames Iowa are developing a soil quality index that may give the right quality index that may give the right parameters to analyze.parameters to analyze.

Soil Quality IndexSoil Quality Index

Total Organic CTotal Organic C Potential Potential

Mineralizable NMineralizable N Soil pHSoil pH Soil Extractable PSoil Extractable P Sodium Sodium

Adsorption RatioAdsorption Ratio Electrical Electrical

ConductivityConductivity

Microbial Microbial Biomass CBiomass C

Microbial Microbial Quotient qCOQuotient qCO22

Macroaggregate Macroaggregate StabilityStability

Available Water Available Water CapacityCapacity

Bulk DensityBulk Density

Carbon CycleCarbon Cycle

Total Organic CarbonTotal Organic Carbon

Soil Organic Matter testSoil Organic Matter test– Loss on Ignition (LOI)Loss on Ignition (LOI)

Carbon AnalyzerCarbon Analyzer Soil Organic Matter is 58 % CSoil Organic Matter is 58 % C Food for MicrobesFood for Microbes

Microbial BiomassMicrobial Biomass

Biological Activity Biological Activity Active Soil CarbonActive Soil Carbon Increases with Cropping IntensityIncreases with Cropping Intensity Measurement involves Incubation Measurement involves Incubation

for 3 days or morefor 3 days or more

Particulate Organic Particulate Organic MatterMatter Decomposed ResidueDecomposed Residue Slow Turnover Pool of OMSlow Turnover Pool of OM Soils with the Most Intensive Soils with the Most Intensive

Cropping System Contains the Cropping System Contains the Highest POMHighest POM

Major Substrate used by MicrobesMajor Substrate used by Microbes

Mineral Associated Mineral Associated Organic CarbonOrganic Carbon This Organic Carbon is Not This Organic Carbon is Not

Influenced by Cropping IntensityInfluenced by Cropping Intensity It is the Largest Supply of Organic It is the Largest Supply of Organic

CarbonCarbon Takes Years to IncreaseTakes Years to Increase Stabilized (that part we could not Stabilized (that part we could not

destroy by tillage)destroy by tillage)

Nitrogen CycleNitrogen Cycle

Nitrogen CycleNitrogen Cycle

Plant and Animal Residue/Organic Plant and Animal Residue/Organic Soil N/Air NSoil N/Air N

Microorganisms Microorganisms Ammonification (NH4) – Plant Ammonification (NH4) – Plant

Uptake – Soil ComplexUptake – Soil Complex Nitrification (NO3) – Plant Uptake – Nitrification (NO3) – Plant Uptake –

Leaching - DenitrificationLeaching - Denitrification Immobilization (Soil Organic N)Immobilization (Soil Organic N)

Sulfur CycleSulfur Cycle

Sulfur Cycle

Plant and Animal Residues/Organic Soil S Microbial Breakdown

– Oxidation/Reduction

Sulfates/Sulfides and from Fertilizers, etc Sulfate

– Plant uptake– Leaching– Soil Minerals

No-Till Sulfur No-Till Sulfur DeficiencyDeficiency Most of the Sulfur in the soil is Most of the Sulfur in the soil is

held in the organic matter portion held in the organic matter portion of the soilof the soil

The idea is to build organic matter The idea is to build organic matter to improve the health of the soil to improve the health of the soil and increase productivityand increase productivity

C : N : S ratioC : N : S ratio 100C : 8N : 1S100C : 8N : 1S

Soil Sample DepthSoil Sample Depth

Evaluating No-TillEvaluating No-Till– 0-2 inches most active0-2 inches most active– 2-6 inches 2-6 inches – 6-12 inches6-12 inches

Evaluating FertilityEvaluating Fertility– 0-8 inches for all nutrients0-8 inches for all nutrients– 8-36 inches for Nitrate, Chloride, 8-36 inches for Nitrate, Chloride,

Sulfate Sulfate

Nutrient Uptake and Nutrient Uptake and Root StructureRoot Structure

Granular StructureGranular Structure

Microbe TestsMicrobe Tests

Soil pHSoil pH

Important for Crop GrowthImportant for Crop Growth Important for Microbe GrowthImportant for Microbe Growth Tendency to Decrease over TimeTendency to Decrease over Time Some Herbicides Less Affective at Some Herbicides Less Affective at

Low pHLow pH Broadleaf Crops Contain more Broadleaf Crops Contain more

Calcium and Magnesium Calcium and Magnesium

Optimum Soil pHOptimum Soil pH

CropCrop Mid Point Mid Point Range (+/-)Range (+/-)

WheatWheat 6.36.3 .75 .75

CornCorn 6.36.3 2.0 2.0

SoybeanSoybean 6.36.3 1.2 1.2

SunflowerSunflower 6.66.6 2.1 2.1

Field PeasField Peas 6.56.5 1.0 1.0

Nitrate Soil TestNitrate Soil TestConsider nitrate in your root zoneConsider nitrate in your root zone

Total Lbs/A are availableTotal Lbs/A are available

Subtract total Lbs/A from N requirementSubtract total Lbs/A from N requirement

N recommendation based on nitrate in N recommendation based on nitrate in the root zonethe root zone

Phosphorus Soil TestPhosphorus Soil Test

Soil test ppm PSoil test ppm P Rating Rating % Sufficiency % Sufficiency

0-50-5 Very LowVery Low 25-5025-50

6-126-12 LowLow 45-8045-80

13-2513-25 MediumMedium 70-9570-95

26-5026-50 HighHigh 90-10090-100

51+51+ Very HighVery High 100 100

Phosphorus deficiencyPhosphorus deficiency

Potassium Soil TestPotassium Soil Test

Soil Test ppm K RatingSoil Test ppm K Rating% Sufficiency% Sufficiency

0-400-40 Very LowVery Low 20-5020-50

41-8041-80 LowLow 45-8045-80

81-12081-120 MediumMedium 70-9570-95

121-200121-200 HighHigh 90-10090-100

201+201+ Very HighVery High 100100

Sulfur Soil TestSulfur Soil Test

Soil Test ppm SSoil Test ppm S RatingRating

0-30-3 Very LowVery Low

4-64-6 LowLow

8-128-12MediumMedium

13-2013-20 HighHigh

20+20+ Very HighVery High

Sulfur in WheatSulfur in Wheat

Sulfur DeficiencySulfur Deficiency

Zinc Soil TestZinc Soil Test Soil Test ppm Zn Soil Test ppm Zn Rating Rating

0-.250-.25 Very LowVery Low

.26-.50.26-.50 LowLow

.51-1.00.51-1.00 MediumMedium

1.01+1.01+ HighHigh

Zinc Deficiency WheatZinc Deficiency Wheat

Zinc deficiencyZinc deficiency

Zinc Deficiency WheatZinc Deficiency Wheat

Copper Soil TestCopper Soil Test

0-.200-.20 LowLow .20-.60.20-.60 MediumMedium >.60>.60 HighHigh

Copper Deficiency Copper Deficiency WheatWheat

Copper Deficiency Copper Deficiency WheatWheat