diagnostic nutrient testing
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Rao MylavarapuSoil & Water Science Department, IFAS
University of Florida
Optimum Yield or Optimum Yield or QualityQuality‘‘Optimum’ should Optimum’ should
ideally refer to ideally refer to economically and economically and environmentally environmentally sustainable returns sustainable returns
Existing Existing approaches have approaches have been been predominantly predominantly based on based on economicseconomics
Profit
No Soil TestingNo Soil Testing
Always FertilizeAlways Fertilize
Luxury Luxury
ConsumptionConsumption
Pollution Pollution
Potential HiPotential Hi
Treats soil as a Treats soil as a
bankbank
Calibrated Soil Calibrated Soil TestTest
Fertilizer Fertilizer amounts amounts adjusted for soil adjusted for soil contributioncontribution
Based on plant Based on plant need, not plant need, not plant uptakeuptake
Pollution Pollution Potential LowPotential Low
Fertilize the Fertilize the plant not the soilplant not the soil
Soil Categories & Extractants Soil Categories & Extractants for Floridafor FloridaAcid soils Acid soils - - Mehlich-1 Mehlich-1 (dilute double (dilute double
acid)acid)
-P, K, Ca, Mg, Cu, Zn, Mn-P, K, Ca, Mg, Cu, Zn, Mn
Calcareous soils Calcareous soils (pH (pH >> 7.4) - 7.4) - AB-DTPA AB-DTPA (Ammonium Bicarbonate-DTPA)(Ammonium Bicarbonate-DTPA)
-P only-P only
Organic soils Organic soils
--Water Water extraction for phosphorusextraction for phosphorus
--Acetic Acid Acetic Acid for K, Mg, Ca, Na, Sifor K, Mg, Ca, Na, Si
Field CalibrationField CalibrationAB-DTPA extraction procedure for AB-DTPA extraction procedure for
calcareous soils needs to be replaced calcareous soils needs to be replaced urgentlyurgently
-poor field calibration with the procedure -poor field calibration with the procedure severelyseverely
limits its applicabilitylimits its applicability-extremely high carbonate levels make -extremely high carbonate levels make calibration difficultcalibration difficult-background P concentration higher than -background P concentration higher than the critical limitthe critical limit-both commercial and urban horticultural -both commercial and urban horticultural operations lack a valid soil testoperations lack a valid soil test
Soil and plant diagnostics are complementary Soil and plant diagnostics are complementary and serve different purposes and serve different purposes
Tissue test does not completely replace a soil Tissue test does not completely replace a soil test test
Plant analysis is effective in monitoring in-Plant analysis is effective in monitoring in-season nutrient needs, especially of perennial season nutrient needs, especially of perennial cropscrops
The tissue tests confirm suspected nutrient The tissue tests confirm suspected nutrient deficiency symptoms, reveal hidden hunger deficiency symptoms, reveal hidden hunger and verify toxicitiesand verify toxicities
Nutrient deficiencies corrected through foliar Nutrient deficiencies corrected through foliar applications, although not always effectiveapplications, although not always effective
Leaf diagnosis shows nutrient status Leaf diagnosis shows nutrient status at the time of sampling reflecting soil at the time of sampling reflecting soil fertility status fertility status
Soil fertility status in turn is also Soil fertility status in turn is also determined by temperature, water, determined by temperature, water, management factors, nutrient balance, management factors, nutrient balance, etcetc
Leaf analysis has to be integrated with Leaf analysis has to be integrated with soil analysis for confirming the soil analysis for confirming the deficiency, sufficiency or toxicitydeficiency, sufficiency or toxicity
Complementary Soil & Complementary Soil & Tissue TestingTissue TestingTwo such new tests have been Two such new tests have been
developed and implementeddeveloped and implemented
- for Bahia pastures - for Bahia pastures
-for commercial Citrus -for commercial Citrus
In both tests, phosphorus requirement In both tests, phosphorus requirement and deficiency confirmation is and deficiency confirmation is determined by a combination of both determined by a combination of both soil and a plant tissue testsoil and a plant tissue test
Potential for a new protocol for Potential for a new protocol for Blueberries Blueberries
Plant Sap AnalysisPlant Sap Analysis
NIR Spectrophotometry NIR Spectrophotometry Technique providesTechnique provides
• routine soil analysisroutine soil analysis• decision supportdecision support• soil property classificationsoil property classification• soil survey and mappingsoil survey and mapping• precision agricultureprecision agriculture• diagnosis of soil problemsdiagnosis of soil problems• contaminated site characterization contaminated site characterization • input data for modelsinput data for models
Why Replace Wet Chemistry?Why Replace Wet Chemistry?
Soil Test Laboratory Soil Test Laboratory TechniquesTechniques
ReflectancReflectance e MeasuremMeasurementent
Signal Signal ProcessingProcessing
Statistical Statistical AnalysisAnalysis
ValidatioValidationn
CalibratiCalibrationon
InterpretatioInterpretation &n &RecommendRecommendationation
Previous WorkPrevious Work
Wavelength (nm)
500 1000 1500 2000 2500
log(1
/Reflecta
nce)
0.2
0.4
0.6
0.8
1.0
1.2
Alfisol Entisol Ultisol
WaterWater
PredictPredicted & ed & ValidatValidated Soil ed Soil PropertPropertiesies
Study 3 (on-going) Study 3 (on-going) A sample set consisting of 1,000 soil and A sample set consisting of 1,000 soil and
corresponding 1,000 tissue samples is corresponding 1,000 tissue samples is being collected from through out the being collected from through out the statestate
Commodities targeted- forages, Commodities targeted- forages, vegetables, peanuts, citrus (Ridge, vegetables, peanuts, citrus (Ridge, Flatwoods and Indian River)Flatwoods and Indian River)
Soil and leaf tissue reflectances will be Soil and leaf tissue reflectances will be correlatedcorrelated
A subset of soil samples was used to A subset of soil samples was used to determine the influence of multiple determine the influence of multiple moisture levelsmoisture levels
Soil texture will also be determined for a Soil texture will also be determined for a subset of soil samplessubset of soil samples
Mylavarapu, R.S., Schumann, A.W., Obreza, Mylavarapu, R.S., Schumann, A.W., Obreza, T.A., Cornejo, C. 2007. Rapid Soil & Tissue T.A., Cornejo, C. 2007. Rapid Soil & Tissue Analysis Techniques Using Near Infrared Analysis Techniques Using Near Infrared Reflectance Spectroscopy. FDACS Project Reflectance Spectroscopy. FDACS Project 61580, Annual Progress Report. 61580, Annual Progress Report.
ResultsResultsPLSR for P in PLSR for P in
DRY and DRY and MOIST soils MOIST soils samples samples respectivelyrespectively– Moist refers Moist refers
to samples as to samples as they arrive they arrive from the fieldfrom the field
– Dry samples Dry samples are oven dryare oven dry
Dry
Moist
Part A: Transport Potential Due to Site and Transport Characteristics
Site and Transport Characteristics
Phosphorus Transport Rating Value
Soil Erosion No Surface Outlet
0
<5T/Aa
15-10 T/A
210-15 T/A
4>15 T/A
8
Runoff Potential Very Low0
Low1
Medium2
High4
Very High8
Leaching Potential Very Low0
Low1
Medium2
High4
Very High8
Potential To Reach Water Body
Very Low0
Low1
Medium2
High4
Total for Part A: Site and Transportb
Part B: Transport Potential Due to Phosphorus Source Management
Phosphorus Source Management
Phosphorus Loss Rating Value
Fertility Index ValueSoil Fertility Index x 0.025( _____ ppm P x 2 x 0.025)c
P Application Source and Rate d
0.05 x ( _____ lbs P2O5) for fertilizer, manure or compost
0.015 x ( _____ lbs P2O5) for biosolids
0.10 x ( _____ lbs P2O5) for waste water
Application Method
NoSurface Outlet
Or Solids incorporated immediately or injected
Applied via irrigationOr Solids
incorporated within 1 day
of application
Solids incorporated
within 5 days of application e
Solids not incorporated within 5
days of application
0 2 4 6
Waste Water Application
0.20 x _____ acre inches/year
Total for Part B: Phosphorus Source
Multiply Part A x Part B
THE
FLORIDA
P
INDEX
PrioritiesPrioritiesDetermine the feasibility of complementary Determine the feasibility of complementary
soil and tissue analyses for phosphorus soil and tissue analyses for phosphorus management for perennial crops and management for perennial crops and landscape plants and grasseslandscape plants and grasses
Integrate recommendations for irrigation Integrate recommendations for irrigation management with nutrient management with nutrient recommendations for commercial recommendations for commercial horticultural cropshorticultural crops
Further develop VNIR techniques and Further develop VNIR techniques and continue field calibration for wider continue field calibration for wider diagnostic applicationsdiagnostic applications
Develop newer diagnostic techniques for Develop newer diagnostic techniques for environmental impact assessmentenvironmental impact assessment
Thank You!raom@ufl.edu
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