Soil Sampling and Nutrient Recommendations Soil Education Short Course.
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Transcript of Soil Sampling and Nutrient Recommendations Soil Education Short Course.
Soil Sampling and Soil Sampling and Nutrient Nutrient
RecommendationsRecommendations
Soil Education Short CourseSoil Education Short Course
OutlineOutline
How to take a soil sampleHow to take a soil sampleWhat is the appropriate depth for soil testsWhat is the appropriate depth for soil tests
How many should you takeHow many should you take
How often should we sampleHow often should we sample
Preparing samples for lab analysisPreparing samples for lab analysis
Good or not-so-good soil testsGood or not-so-good soil tests
Nutrient RecommendationsNutrient RecommendationsN recommendation ModelN recommendation Model
P and K (Sufficiency and Build-Maintain)P and K (Sufficiency and Build-Maintain)
Why Should We Soil Why Should We Soil Test?Test?
Determine plant available nutrients Determine plant available nutrients in soilin soil
Estimate crop responses to nutrient Estimate crop responses to nutrient additionsadditions
Record long-term soil fertility trendsRecord long-term soil fertility trends Problem solvingProblem solving Generate nutrient recommendationsGenerate nutrient recommendations Make financial decisionsMake financial decisions
Appropriate Soil Sample Appropriate Soil Sample DepthDepth
Consistently take samples from the Consistently take samples from the same depthsame depth
6 inch sample – P, K, pH, Organic 6 inch sample – P, K, pH, Organic MatterMatter
Approximate depth of historical tillageApproximate depth of historical tillage
24 inches – Nitrate, Chloride, Sulfate24 inches – Nitrate, Chloride, Sulfate
Mobile nutrients can be taken up from Mobile nutrients can be taken up from deeper in the soildeeper in the soil
Number of Soil SamplesNumber of Soil Samples
Number of soil samples for specific Number of soil samples for specific accuracyaccuracy
pHpH PP KK OMOM
+/-+/- ## +/-+/- ## +/-+/- ## +/-+/- ##
0.10.1 337337 11 337337 1010 164164 0.10.1 8989
0.20.2 8585 55 1414 2525 2727 0.20.2 2323
0.30.3 3838 1010 44 5050 77 0.30.3 1010
0.40.4 2121 1515 22 100100 22Kansas State University
Number of composite samples Number of composite samples submitted to the lab depends on submitted to the lab depends on management areasmanagement areas
15-20 subsamples for each 15-20 subsamples for each composite samplecomposite sample
Number of Soil SamplesNumber of Soil Samples
Number of composite samples may Number of composite samples may depend on field variabilitydepend on field variability
Identify management zones Identify management zones
Number of Soil SamplesNumber of Soil Samples
Number of composite samples may Number of composite samples may depend on field variabilitydepend on field variability
Identify management zones Identify management zones
Number of Soil SamplesNumber of Soil Samples
Creek
Slope
Low land
Number of composite samples may Number of composite samples may depend on field variabilitydepend on field variability
Identify management zones Identify management zones
Number of Soil SamplesNumber of Soil Samples
Creek
Slope
Low land Sand
y Loam
Sandy Loam
Silt Loam
Number of Soil SamplesNumber of Soil Samples
Grid soil samplingGrid soil samplingRequires more samples and ultimately Requires more samples and ultimately more costmore cost
60 ac field divided into ~2 ac grids60 ac field divided into ~2 ac grids
Grid Soil SamplingGrid Soil Sampling
May be beneficial in highly variable May be beneficial in highly variable fieldsfields
GPS and precision application GPS and precision application equipment make this possibleequipment make this possible
How Often Should We How Often Should We Sample Sample
Every year until a history is Every year until a history is establishedestablished
Historical trends is a strong point of soil Historical trends is a strong point of soil testingtesting
Generally recommended every 3-4 Generally recommended every 3-4 yearsyears
Time →
Soil
Test
→
Crop Removal < Fertilizer
Crop Removal > Fertilizer
Preparing Samples for Preparing Samples for LabLab
Know your objectivesKnow your objectivesLaboratory data is only as good as the Laboratory data is only as good as the sample submitted – regardless of the labsample submitted – regardless of the lab
Combine subsamples into composite Combine subsamples into composite samplessamples
Keep uniform depth and mix thoroughlyKeep uniform depth and mix thoroughly
Avoid contamination – buckets used for Avoid contamination – buckets used for mixingmixing
Know how much sample to submit – a Know how much sample to submit – a sandwich bag is usually enoughsandwich bag is usually enough
Drying samplesDrying samplesNot necessary except nitrate samples Not necessary except nitrate samples that are not submitted immediatelythat are not submitted immediately
Nitrate – lay out on paper, turn on fanNitrate – lay out on paper, turn on fanDon’t – put it in the oven or microwave itDon’t – put it in the oven or microwave it
Freezing is an option for nitrate Freezing is an option for nitrate samplessamples
Fill out paperwork including Fill out paperwork including relevant historical informationrelevant historical information
Preparing Samples for Preparing Samples for LabLab
Where To Send Your Where To Send Your SamplesSamples
Your objectives! What is important?Your objectives! What is important?Tests appropriate for your areaTests appropriate for your area
Accurate resultsAccurate results
Turn around timeTurn around time
CostCost
ServiceService
Part of a government program?Part of a government program?Ask your local extension agent what Ask your local extension agent what tests are required – Don’t assume all tests are required – Don’t assume all labs provide the same required tests!labs provide the same required tests!
Choosing Soil TestsChoosing Soil TestspH (1:1 soil:water)pH (1:1 soil:water)
Very accurate and reliableVery accurate and reliable
Substantial research conducted on pHSubstantial research conducted on pH
Determines if lime is neededDetermines if lime is needed
pH > 7.3 – calcium carbonate present pH > 7.3 – calcium carbonate present (free lime)(free lime)
pH < 5.8 – crop response to limepH < 5.8 – crop response to lime
Buffer pH (Buffer Index)Buffer pH (Buffer Index)Very accurate and reliableVery accurate and reliable
Tells how much lime to addTells how much lime to add
SMP is most commonSMP is most common
Choosing Soil TestsChoosing Soil Tests
PhosphorusPhosphorusVariety of testsVariety of tests
Bray P-1Bray P-1Most correlation/calibration dataMost correlation/calibration data
Inaccurate on calcareous soil (reads low)Inaccurate on calcareous soil (reads low)
Olsen POlsen PSpecific to high pH soil (abundant data on Specific to high pH soil (abundant data on high pH)high pH)
Mehlich 3Mehlich 3Works on a wide range of soil pH (acid → Works on a wide range of soil pH (acid → calcareous)calcareous)
Limited correlation/calibration dataLimited correlation/calibration data
Most commonMost common
Choosing Soil TestsChoosing Soil Tests
PotassiumPotassiumExchangeable ammonium acetateExchangeable ammonium acetate
Fairly good testFairly good test
Most useful for watching trends over Most useful for watching trends over timetime
NitrateNitrateKCl extractableKCl extractable
Abundant dataAbundant data
Based on expected yieldBased on expected yield
Adjusted based on organic matter, Adjusted based on organic matter, previous crop, fallow previous crop, fallow
Organic Matter (%)Organic Matter (%)Modified Walkley-Black or loss on ignitionModified Walkley-Black or loss on ignition
Reliable, consistent dataReliable, consistent data
May be inflated if crop residue is in sampleMay be inflated if crop residue is in sample
Warm season crop N adjustment = %OM×20Warm season crop N adjustment = %OM×20
Cool season crop N adjustment = %OM×10Cool season crop N adjustment = %OM×10
ZincZincDTPA extract – diethylenetriaminepentacetic DTPA extract – diethylenetriaminepentacetic acidacid
Good predictor of crop responseGood predictor of crop response
Reliable on high pH soil, less on acid soilsReliable on high pH soil, less on acid soils
Choosing Soil TestsChoosing Soil Tests
SulfateSulfateCalcium phosphate extractCalcium phosphate extract
Little calibration dataLittle calibration data
Variable crop responseVariable crop response
Credit from organic matter (2.5 × % OM)Credit from organic matter (2.5 × % OM)
CEC (Cation Exchange Capacity)CEC (Cation Exchange Capacity)Measured by summation (KMeasured by summation (K++, Ca, Ca++++, Na, Na++, , HH++))
Soil’s potential to ‘hold’ nutrientsSoil’s potential to ‘hold’ nutrients
Overestimates on calcareous soilsOverestimates on calcareous soils
Choosing Soil TestsChoosing Soil Tests
IronIronDTPA extractableDTPA extractable
Poor calibration dataPoor calibration data
Inadequate for acid soilsInadequate for acid soils
Limited use for calcareous soilLimited use for calcareous soil
Calcium, Magnesium, Manganese, Calcium, Magnesium, Manganese, MolybdenumMolybdenum
Poorly calibratedPoorly calibrated
Deficiency is rareDeficiency is rare
Choosing Soil TestsChoosing Soil Tests
BoronBoronPoor calibrationPoor calibration
Poor soil testPoor soil test
Used for alfalfa grown on sandy soilUsed for alfalfa grown on sandy soil
CopperCopperPoor CalibrationPoor Calibration
Deficiency is rareDeficiency is rare
Occasional deficiency in wheat on Occasional deficiency in wheat on organic soilorganic soil
Choosing Soil TestsChoosing Soil Tests
Exchangeable Sodium PercentageExchangeable Sodium Percentage Fairly reliableFairly reliable Diagnoses alkali/sodic soilsDiagnoses alkali/sodic soils
Soluble Salts (Electrical Soluble Salts (Electrical Conductivity)Conductivity) 1:1 soil to water paste1:1 soil to water paste Diagnoses saline soilDiagnoses saline soil
Choosing Soil TestsChoosing Soil Tests
Soil Tests SummarySoil Tests SummaryGoodGood QuestionableQuestionable
pHpH CalciumCalcium
Buffer pHBuffer pH MagnesiumMagnesium
PhosphorusPhosphorus CopperCopper
PotassiumPotassium ManganeseManganese
NitrateNitrate MolybdenumMolybdenum
Organic MatterOrganic Matter
ZincZinc
ChlorideChloride
ESPESP
Soluble SaltsSoluble Salts
Nutrient Nutrient RecommendationsRecommendations
Available at:http://www.agronomy.ksu.edu/SoilTesting