Replacing SOIL TESTING

In-Season Soil TestingUse of an in-season soil test for N availability in corn PSNT (0-30cm), Magdoff et al. (1984).Separating nitrate test calibration data based on yield potential of soils may improve PSNT and PPNT for making N recommendations in corn, when NO3 test values are in the N responsive region (Bundy and Andraski, 1995)No soil test accurately predicted either relative grain yield or N-supplying capacity (Fox et al., 1993).Relative grain yield vs PSNT relationship was better with NO3 and NH4 than with NO3 alone (Meisinger et al., 1992)

SufficiencyLevels of available nutrients range in a group of soils from insufficient to sufficient for optimum plant growthAmounts of nutrients removed by suitable extractants will be inversely proportional to yield increases from added nutrientsCalibrations have been made for changing the levels of available nutrients in the soil by adding fertilizer

Mobile NutrientYield Goal (Risk assessment of the environment)

Immobile NutrientSufficiency Level (Independent of Environment, % of Maximum yield)

Root Surface Sorption Zone Response does not depend on reservoir Indicator of availability Independent of environment Response depends on reservoir Indicator of total available Dependent on environmentRoot System Sorption ZoneDepends on Growth Stage IndicatorsBiomassColorConcentrationIndependent of Growth Stage

IndicatorsBiomassColorNO3-H2PO4-Brays Mobility ConceptHPO4=Sensor ViewSoil TestMobile NutrientsImmobile NutrientsSensor

Present N RecommendationFertilizer N = yield goal (bu/ac)*2 - soil test NO3-N

Future N RecommendationEstimated topdress N = f (yield potential and total N uptake, estimated using indirect measures)

Could we establish a sufficiency level(by growth stage, variety, etc) at Feekes 5? NDVIN UptakeSuff.N Rec0.33540Yld goal*1.50.54560Yld goal*1.00.75580Yld goal*0.70.965100Yld goal*0.2

Sunlight reachingearthChlorophyll bB-CarotenePhycoerythrinPhycocyaninChlorophyll a300400500600700800Wavelength, nmAbsorptionSPAD 501, 502(430, 750)Absorption of Visible Lightby PhotopigmentsCAUSE/EFFECT

Soil testing vs. Sensor based systems for developing nutrient recommendations

Soil TestingSensor Based Analyses DetectionPlant availablePlant statusSample collection >20 hectares1m2Samplingsoil, destructiveplant, non-destructiveMethodExtraction & chemicalSpectral radiance,analyseswavelength specificAnalytical parameterNutrient elementSpectral radianceInterpretationCalibration with yieldCalibration with yieldFertilizer Rec.Procedure specificWavelength/index specific

Interfering Factors Affecting Fertilizer RecommendationNumber of samples (reliability)Subsoil N availability--Weeds-Clouds-Time of day (sun angle)-Variety-Stage of growth (% cover)-Living vs. dead plant tissueField element sizeField element sizeCalibration curveCalibration curve

Evolution of a soil testEvolution of a spectral test

ExtractionCorrelationCalibrationOn-farmSuff.Procedurewith fieldof rates at validationIndexresponsea given soiltest level

WavelengthCorrelationCalibrationOn-farmSuff./Index/bandwith fieldof rates atvalidationIndexresponsea given ___env. spec.

NDVIStrengthsSensitive to canopy cover in sparse canopiesExcellent predictor of total N uptake (vegetative stages)Amount of variability in N uptake explained by NDVI increases with advancing growth stage (% coverage)Good predictor of N uptake following freeze damagePrairie biomass (fuel load)Foliage surface area (pine)N fertilization need in maize (pre-flowering) 1996 Agron. J.Area affected by forest firesWeaknessesNot sensitive to canopy cover in dense canopies (2D not 3D)Not a good predictor of N concentration

IndicesLandsat Satellite Thermic Mapper (TM) mid and near infrared indicesplant density, drought, tillageSR (simple ratio)=NIR/redNDVI (normalized difference vegetation index) = (NIR-red)/(NIR+red)biomass, forage N uptake, water stress, leaf area indexG-NDVI = (NIR-green)/(NIR+green)STVI (stress related vegetation index)MPDI (microwave polarization difference index)NPCI (normalized pigment chlorophyll ratio index) =(R680-R430)/(R680+R430)

IndicesWBI (water band index) = R970-R900PRI (physiological reflectance index) = (R550-R530)/(R550+R530) narrow waveband spectral measurements (sunflower)chlorophyll, net CO2 uptake, water potential, light use efficiency

What should we learn from soil testing?Process of eliminationJustus von Leibig (1803-1873) Leibigs Law of the Minimum; nutrient present in the least relative amount is the limiting nutrient for plant growthall other nutrients present in excess until the deficient or limiting nutrient was in adequate supplyFather of soil testingLiebig Hyperlink

Fact Sheet 2225Cropsmall grains, sorghum, corn, cotton, cool season grasses, weeping lovegrass, bluestem, bermudagrass, forage sorghum or corn silage, small grains for grazing, legumes in pasture, native meadows, alfalfa, peanuts, soybeans, mungbeans, cowpeasN, P, K, S, Ca, Mg, Zn, Fe, Mn, Cu, BpH/buffer index (lime)

Could N uptake be used as an indicatorof yield potential when other variables are controlling response?

Should we develop technologies that treat variable yield potential

What influences NDVI?How can I use the NDVI measurement from last year, this year?

Soil Testing: Method of Extraction

PhosphorusFluoresce= reemit light energy absorbed as light but of a longer wavelength and of lower energyFluorescence spectrum is characteristic of the pigment, so it is possible to tell which pigment is fluorescing (which one was activated)Low P nutrition results in increased chlorophyll fluorescence, reduced photosynthetic rate, increased starch and sucrose in leavesIf the reactions of photosynthesis are blocked (chemical, cold, etc.) fluorescence will occur in-vivo because the energy absorbed cannot be used. x-ray fluorescence (total P in plants)Time required to induce/measure fluorescence (1-2 min) Xanthophyll

Subsoil nutrient availability

Can sensor based technologies assess subsurface nutrient availability?Sensing with time (Stage of growth) could provide an indicator of subsurface nutrient availability

T1T2T3T4

VISIBLE Color Absorbed VISIBLE Color TransmittedVioletBlueGreenYellowOrange RedShort wavelengthHigh frequencyHigh energyLong wavelengthLow frequencyLow energy0.01103804504955705906207501x1061x1011 wavelength, nmGamma RaysX-RaysUltravioletInfraredMicrowaves and short radioRadio, FM, TVElectronicVibrationalRotationaltransitionstransitionstransitionsYellow-greenYellowVioletBlueGreen-blueBlue-green

Models for Interpretation of ResponseLinearLinear-plateauQuadraticSquare rootQuadratic-plateauCate-Nelson

20 mpg400 milesGallons20

3510 mpg350 miles40 30 60 20YIELD POTENTIALTRIP DISTANCEN FERTILIZER NEEDYP0 = 100 bushels YPN = 140 bushels (RI of 1.4) Grain N Uptake based on YPN of 140 bu/ac = 140 bu/ac * 56 lb/bu * 1.18%N = 92.5 lbHave 60 kg N in the plant Need = (92.5-60)/0.7 = 46.4

Crop ProductionTravel PlanningYield Potential (YP0)Trip DistanceYield Potential withTrip Distance (adj.) added N (YPN)Forage N UptakeAmount of Gas in Tank Grain N Uptake (YPN)Total Gallons NeededFertilizer NeedTotal Gallons-Amt in TankTopdress N rate rangeFuel efficiency(rainfall, temp(windspeed, frost, plant stand,direction, road weed population)conditions, uphill, downhill, etc.)

Interfering agronomic factorsMoisture availability (texture, water holding capacity)Nutrient(s) deficiency(ies) and/or toxicity(ies) interactionsCropVariety within cropPreplant N rateProduction system (forage vs. grain)Tillage (background)Weed interferenceRow spacing (coverage, plant density)Resolution to be treated (field element size)cost of misapplication (economic vs. environment)

Hennessey, Feekes 4, 5 and 7Feekes Growth Stage 7y = 234.78x - 9.4074R2 = 0.728605010015020025000.20.40.60.8NDVITotal N Uptake, kg/haFeekes Growth Stage 5y = 97.953x - 12.413R2 = 0.6687Feekes Growth Stage 4y = 286.62x - 20.226R2 = 0.3588

0102030405060700-1010-2020-3030-4040-5050-6060-7070-8080N rate, kg/haFrequencyFrequency Distribution of VariableNitrogen Rates (4, 1x42m transects)800NDVI0.3 0.4 0.5 0.6 0.7 0.8 0.9Max. N Rate determined by farmer

TreatmentTreatmentNumber of ResolutionSubplots

10.84 m26423.34 m216313.38 m24453.51 m21RESOLUTION STUDY Treatment Structure

Contour map of NDVI values at Tipton, OK01 02 03 0408 07 06 0509 10 11 1216 15 14 1301 0204 030101 02 03 0408 07 06 0509 10 11 1216 15 14 1301 02 03 0408 07 06 0509 10 11 1216 15 14 1301 02 03 04 05 06 07 0816 15 14 13 12 11 10 0917 18 19 20 21 22 23 2432 31 30 29 28 27 26 2533 34 35 36 37 38 39 4048 47 46 45 44 43 42 4149 50 51 52 53 54 55 5664 63 62 61 60 59 58 570101 02 03 04 05 06 07 0816 15 14 13 12 11 10 0917 18 19 20 21 22 23 2432 31 30 29 28 27 26 2533 34 35 36 37 38 39 4048 47 46 45 44 43 42 4149 50 51 52 53 54 55 5664 63 62 61 60 59 58 570101 02 03 04 05 06 07 0816 15 14 13 12 11 10 0917 18 19 20 21 22 23 2432 31 30 29 28 27 26 2533 34 35 36 37 38 39 4048 47 46 45 44 43 42 4149 50 51 52 53 54 55 5664 63 62 61 60 59 58 5701 0402 0301 0402 03NDVI0.480.450.420.390.360.330.300.270.240.210.18

0510152025300.260.30.340.380.420.460.50.540.580.620.660.70.740.78NDVIFrequencyDistribution of NDVI values, Tipton, OK

Percent Coverage355585NDVI0.30.50.7Tipton, January 15, 1998, Feekes 5Fertilizer N Rate

Percent Coverage355585NDVI0.30.50.7Tipton, January 15, 1998, Feekes 5

Res.N RateSDYieldSDEfficiencySDN UptakeSDm2kg/hakg/haof Use**kg/ha_______________________________________________0.8456.9519.04232316244.2515.6551.531.883.3474.1718.43232938233.4712.5252.305.8113.3869.2823.13247323338.7713.7954.214.6753.5173.9325.26255526637.5813.9560.276.63SED13.971277.283.22

** Moll et al., 1982Location: Perkins, 1997-98

Spectral radiance (250-830 nm) collected from individual plots, NxP bermudagrass experiment, Burneyville, OK00.050.10.150.20.25250350450550650750850Wavelength, nmSpectral radiance, %N0 P0N0 P60N0 P120N100 P0N100 P60N100 P120N200 P0N200 P60N200 P120N300 P0N300 P60N300 P120RedNIRGreenHasil SembiringOSU Soil Fertility

TrtN rateP rate1002400380041200501064010780108120109020104020118020121202010 ft30 ft

Source of variationdfPNw919w791Total (r*N*P)-135--Rep2nsnsN Rate3ns**P Rate2**nsN Rate * P Rate6nsnsError22--

00.050.10.150.20.250.3276335395455515575635695755815N0 P0N0 P60N0 P12000.050.10.150.20.250.3276335395455515575635695755815N300 P0N300 P60N300 P120Wavelength, nmSpectral radiance, %Hasil SembiringOSU Soil Fertility

Wavelength IDHasil SembiringOSU Soil Fertility404414425--584735775785N0.020.04...-0.010.010.01P.....0.18-0.040.03NP.....-0.010.020.023.33.353.43.453.53.553.63.653.7050100150200250300N Ratew735/w53460300

Contour map was created using Surfer

Discuss trt resolutionsEach location was harvested with a Massey Ferguson 8XP self propelled combine. The entire subplot area was harvested and grain weights and % moisture were automatically recorded. Total N content in grain was analyzed using a Carlo Erba 1500 dry combustion analyzer. N uptake was based on average moistures in grain and percent N.