spatial variability in precision agriculture what is it? what is it? – precision n. the quality or...
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Spatial Variability in Spatial Variability in Precision AgriculturePrecision AgricultureSpatial Variability in Spatial Variability in
Precision AgriculturePrecision AgricultureWhat is it?What is it?
–Precision Precision n.n. The quality or state of being The quality or state of being precise.precise.
Used or intended for precise measurement.Used or intended for precise measurement.Made for the least variation from a set Made for the least variation from a set standard. (Webster, 1995)standard. (Webster, 1995)
–Precise Precise adjadj. Capable of, caused by, or . Capable of, caused by, or designating designating an actionan action, performance, or , performance, or process process carried outcarried out or successively or successively repeated repeated within close specified limitswithin close specified limits (Webster, 1995).(Webster, 1995).
What is it?What is it?–Precision Precision n.n. The quality or state of being The quality or state of being precise.precise.
Used or intended for precise measurement.Used or intended for precise measurement.Made for the least variation from a set Made for the least variation from a set standard. (Webster, 1995)standard. (Webster, 1995)
–Precise Precise adjadj. Capable of, caused by, or . Capable of, caused by, or designating designating an actionan action, performance, or , performance, or process process carried outcarried out or successively or successively repeated repeated within close specified limitswithin close specified limits (Webster, 1995).(Webster, 1995).
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Precision AgriculturePrecision AgriculturePrecision AgriculturePrecision AgricultureWhat is it?What is it?
–Precision in management?Precision in management?–Knowing more precisely the Knowing more precisely the
size of fields, size of fields, level of inputs (rates), level of inputs (rates), yields, yields, $ costs, and $ costs, and $ returns?$ returns?
What is it?What is it?–Precision in management?Precision in management?–Knowing more precisely the Knowing more precisely the
size of fields, size of fields, level of inputs (rates), level of inputs (rates), yields, yields, $ costs, and $ costs, and $ returns?$ returns?
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Precision AgriculturePrecision AgriculturePrecision AgriculturePrecision Agriculture
What is it?What is it?–Management of production inputs in Management of production inputs in relation to more precisely delineated needs relation to more precisely delineated needs (Johnson, 1/18/01).(Johnson, 1/18/01).
Recognizes Recognizes spatial variabilityspatial variability of production of production needs needs withinwithin a population of a population of production units, production units, where production units are where production units are smaller than they smaller than they used to be.used to be.
What is it?What is it?–Management of production inputs in Management of production inputs in relation to more precisely delineated needs relation to more precisely delineated needs (Johnson, 1/18/01).(Johnson, 1/18/01).
Recognizes Recognizes spatial variabilityspatial variability of production of production needs needs withinwithin a population of a population of production units, production units, where production units are where production units are smaller than they smaller than they used to be.used to be.
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Spatial variability among Spatial variability among production units.production units.
Spatial variability among Spatial variability among production units.production units.
What is the size of a production unit?Depends on the enterprise.
– Small dairy = single dairy animal.– Wagoner Ranch, TX = 7,000 – 8,000 acre
wheat field.Agronomic units = “fields”
What is the size of a production unit?Depends on the enterprise.
– Small dairy = single dairy animal.– Wagoner Ranch, TX = 7,000 – 8,000 acre
wheat field.Agronomic units = “fields”
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Spatial variability among Spatial variability among production units.production units.
Spatial variability among Spatial variability among production units.production units.
What causes field delineation.– Natural boundaries.
Rivers Rock out-crops
– Political boundaries. Roads Survey units
– Land ownership Consolidation
What causes field delineation.– Natural boundaries.
Rivers Rock out-crops
– Political boundaries. Roads Survey units
– Land ownership Consolidation
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Spatial variability among Spatial variability among production units.production units.
Spatial variability among Spatial variability among production units.production units.
What causes field delineation.– Soil productivity appropriate to the crop (e.g. bottom land
for alfalfa).– Size determined by land use
Government acreage restrictions (CRP) Tees, fairways, greens
– Size that is “convenient” to the operation for administering production inputs.
Cultivation Planting Harvesting (mowing) Fertilizing Irrigation Etc.
What causes field delineation.– Soil productivity appropriate to the crop (e.g. bottom land
for alfalfa).– Size determined by land use
Government acreage restrictions (CRP) Tees, fairways, greens
– Size that is “convenient” to the operation for administering production inputs.
Cultivation Planting Harvesting (mowing) Fertilizing Irrigation Etc.
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Spatial variability (macro) for Spatial variability (macro) for agronomic land use.agronomic land use.
Spatial variability (macro) for Spatial variability (macro) for agronomic land use.agronomic land use.
Inherent (natural).– Related to soil productivity and soil
forming factors Time Parent material Climate Vegetation Slope
Inherent (natural).– Related to soil productivity and soil
forming factors Time Parent material Climate Vegetation Slope
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Soil acidity and Oklahoma Soil acidity and Oklahoma rainfallrainfall
Soil acidity and Oklahoma Soil acidity and Oklahoma rainfallrainfall
Usually acidic
Usually not acidic
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Spatial variability (macro) for Spatial variability (macro) for agronomic land use.agronomic land use.
Spatial variability (macro) for Spatial variability (macro) for agronomic land use.agronomic land use.
Acquired (use induced). Influence of historical crop production on
soil properties.– Alfalfa vs. wheat for acidification and soil organic
matter. – Fertilizer use and change in soil fertility (Garfield
County).
Acquired (use induced). Influence of historical crop production on
soil properties.– Alfalfa vs. wheat for acidification and soil organic
matter. – Fertilizer use and change in soil fertility (Garfield
County).
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Soil Test P Variability Among First 50 Free Soil Tests for Garfield County Oklahoma, 1997
0
50
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1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49Entry Number
Soil T
est P
Soil Test P Variability Among First 50 Free Soil Tests for Garfield County Oklahoma, 1997
0
50
100
150
200
250
300
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49Entry Number
Soil T
est P
C.V. = 54; ave = 73C.V. = 54; ave = 73
Acquired spatial variability (macro).Acquired spatial variability (macro).Acquired spatial variability (macro).Acquired spatial variability (macro).
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Garfield Co. Farmer’s Use of Soil Testing and FertilizationGarfield Co. Farmer’s Use of Soil Testing and FertilizationGarfield Co. Farmer’s Use of Soil Testing and FertilizationGarfield Co. Farmer’s Use of Soil Testing and Fertilization
PreviousPreviousPreviousPrevious GrainGrainGrainGrain Normal FertilizationNormal FertilizationNormal FertilizationNormal Fertilization Soil Test ResultsSoil Test ResultsSoil Test ResultsSoil Test ResultsAcresAcresAcresAcres Soil TestSoil TestSoil TestSoil Test YieldYieldYieldYield NNNN PPPP2222OOOO5555 KKKK2222OOOO pHpHpHpH NNNN PPPP KKKK
SurSurSurSur SubSubSubSub86*86*86*86* 1981198119811981 35353535 100100100100 46464646 4.54.54.54.5 24242424 54545454 106106106106 445445445445
118*118*118*118* 1981198119811981 25252525 100100100100 46464646 4.94.94.94.9 53535353 108108108108 88888888 41141141141130*30*30*30* 1989198919891989 34343434 100100100100 46464646 5.15.15.15.1 44444444 43434343 75757575 37737737737765*65*65*65* 26262626 100100100100 46464646 4.44.44.44.4 115115115115 118118118118 159159159159 75275275275250505050 1981198119811981 29292929 100100100100 46464646 5.55.55.55.5 0000 70707070 44444444 551551551551
*Savings from no fertilizer to four fields = 299 acres X $24.50/acre, = $7,325*Savings from no fertilizer to four fields = 299 acres X $24.50/acre, = $7,325*Savings from no fertilizer to four fields = 299 acres X $24.50/acre, = $7,325*Savings from no fertilizer to four fields = 299 acres X $24.50/acre, = $7,325
Cost of not managing acquired Cost of not managing acquired spatial variability (macro).spatial variability (macro).
Cost of not managing acquired Cost of not managing acquired spatial variability (macro).spatial variability (macro).
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Acquired spatial variability (micro).Acquired spatial variability (micro).Acquired spatial variability (micro).Acquired spatial variability (micro).
pH=4.9pH=4.9BI = 6.6BI = 6.6N = 10N = 10P = 93P = 93K = 435K = 435
BottomBottompH=5.2pH=5.2BI = 7.0BI = 7.0N = 13N = 13P = 54P = 54K = 354K = 354
Terrace 1Terrace 1
pH=5.3pH=5.3BI = 6.9BI = 6.9N = 10N = 10P = 44P = 44K = 415K = 415
Terrace 2Terrace 2pH=5.7pH=5.7BI = 6.9BI = 6.9N = 20N = 20P = 23P = 23K = 397K = 397
Terrace 3Terrace 3pH=5.4pH=5.4BI = 6.8BI = 6.8N = 20N = 20P = 31P = 31K = 522K = 522
Terrace 4Terrace 4pH=5.5pH=5.5BI = 6.7BI = 6.7N = 12N = 12P = 32P = 32K = 423K = 423
Terrace 5Terrace 5pH=4.6pH=4.6BI = 6.8BI = 6.8N = 16N = 16P = 65P = 65K = 310K = 310
UplandUpland
pH=7.3pH=7.3BI = --BI = --N = 67N = 67P = 22P = 22K = 343K = 343
““BadBadSpot”Spot”pH=5.2pH=5.2
BI = 6.8BI = 6.8N = 14N = 14P = 49P = 49K = 408K = 408
FieldFieldAverageAverage
pH=4.6-5.7pH=4.6-5.7BI = 6.6-7.0BI = 6.6-7.0N = 10-20N = 10-20P = 23-93P = 23-93K = 310-522K = 310-522
FieldFieldRangeRange
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““Cow Pocks” in wheat pastureCow Pocks” in wheat pasture““Cow Pocks” in wheat pastureCow Pocks” in wheat pasture
Acquired spatial variability (micro).Acquired spatial variability (micro).Acquired spatial variability (micro).Acquired spatial variability (micro).
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STP 1996, EFAW
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10
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60
70
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5 25 45 65 85 105 125 145 165 185 205 225 245 265 285 305 325 345 365 385 405 425 445 465 485
Feet North
Soil
Test
P
STP 1996, EFAW
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10
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40
50
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5 25 45 65 85 105 125 145 165 185 205 225 245 265 285 305 325 345 365 385 405 425 445 465 485
Feet North
Soil
Test
P
Acquired spatial variability (micro).Acquired spatial variability (micro).Acquired spatial variability (micro).Acquired spatial variability (micro).
Ave = 47; CV = 30Ave = 47; CV = 30
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1x1 1x1 (60-acre cell)(60-acre cell)1x1 1x1 (60-acre cell)(60-acre cell)
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6x4 6x4 (2.5 acre/cell)(2.5 acre/cell)6x4 6x4 (2.5 acre/cell)(2.5 acre/cell)
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12x8 12x8 (0.625 acre/cell)(0.625 acre/cell)12x8 12x8 (0.625 acre/cell)(0.625 acre/cell)
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25x16 25x16 (0.15 acre/cell)(0.15 acre/cell)25x16 25x16 (0.15 acre/cell)(0.15 acre/cell)
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50x3250x32 (0.0375 acre/cell) (0.0375 acre/cell) 50x3250x32 (0.0375 acre/cell) (0.0375 acre/cell)
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100x64 100x64 (45 yd(45 yd22/cell)/cell)100x64 100x64 (45 yd(45 yd22/cell)/cell)
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200x127 200x127 (11 yd(11 yd22/cell)/cell)200x127 200x127 (11 yd(11 yd22/cell)/cell)
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472x300472x300 (2 yd (2 yd22/cell)/cell)472x300472x300 (2 yd (2 yd22/cell)/cell)
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Management ZonesManagement ZonesManagement ZonesManagement Zones
A
BC
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Fundamentals of Nutrient Fundamentals of Nutrient ManagementManagement
Fundamentals of Nutrient Fundamentals of Nutrient ManagementManagement
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Plant Growth and Soil Nutrient Supply Relationships
•Mitscherlich (1909)“…increase in yield of a crop as a result of increasing a singlegrowth factor is proportional to the decrement from the maximum yield obtainable by increasing the particular growthfactor.”
dy/dx = (A - y) c
Law of “diminishingreturns”
Plant Growth and Soil Nutrient Supply Relationships
•Mitscherlich (1909)“…increase in yield of a crop as a result of increasing a singlegrowth factor is proportional to the decrement from the maximum yield obtainable by increasing the particular growthfactor.”
dy/dx = (A - y) c
Law of “diminishingreturns”
x1 x2x1 x2
y2y2
y1y1
A-y for x1 and y1
A-y for x1 and y1
Yield (y)Yield (y)
Increasing level of growth factor (nutrient, x)Increasing level of growth factor (nutrient, x)
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Plant Growth and Soil Nutrient Supply Relationships
•Mitscherlich– Soil deficiency levels could be expressed as a “percent sufficiency”
Plant Growth and Soil Nutrient Supply Relationships
•Mitscherlich– Soil deficiency levels could be expressed as a “percent sufficiency”
% of MaximumYield or “Yield Possibility”
% of MaximumYield or “Yield Possibility”
Soil Phosphate (P) or Potassium (K) Supply(soil test index)Soil Phosphate (P) or Potassium (K) Supply(soil test index)
100100
5050
7575
10 40 70 10010 40 70 100
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Plant Growth and Soil Nutrient Supply Relationships
•Mitscherlich
Soil Test Correlation and Calibration
Soil Test Percent FertilizerP Index Sufficiency P2O5
0 25 8010 45 6020 80 4040 90 2065+ 100 0
Plant Growth and Soil Nutrient Supply Relationships
•Mitscherlich
Soil Test Correlation and Calibration
Soil Test Percent FertilizerP Index Sufficiency P2O5
0 25 8010 45 6020 80 4040 90 2065+ 100 0
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Plant Growth and Soil Nutrient Supply Relationships
•Bray “…as the mobility of a nutrient in the soil decreases, the amount of that nutrient needed in the soil to produce a maximum yield (the soil nutrientrequirement) increases from a value determined by the magnitude of the yieldand the optimum percentage composition of the crop, to a constant value.”
Plant Growth and Soil Nutrient Supply Relationships
•Bray “…as the mobility of a nutrient in the soil decreases, the amount of that nutrient needed in the soil to produce a maximum yield (the soil nutrientrequirement) increases from a value determined by the magnitude of the yieldand the optimum percentage composition of the crop, to a constant value.”
% of MaximumYield or “Yield Possibility”
% of MaximumYield or “Yield Possibility”
Soil Phosphate (P) or Potassium (K) Supply(soil test index)Soil Phosphate (P) or Potassium (K) Supply(soil test index)
100100
5050
7575
10 40 70 10010 40 70 100
Bray mobile nutrientBray mobile nutrient
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Plant Growth and Soil Nutrient Supply Relationships
•Bray
For a nutrient that is 100 % mobile in the soil (NO3-N ?)
Soil nutrient supply requirement = Yield X % nutrient in tissue
(Input requirement = harvest output or removal)
Idealized situation would be hydroponics nutrient supplying system (no soil-nutrient interaction)
Plant Growth and Soil Nutrient Supply Relationships
•Bray
For a nutrient that is 100 % mobile in the soil (NO3-N ?)
Soil nutrient supply requirement = Yield X % nutrient in tissue
(Input requirement = harvest output or removal)
Idealized situation would be hydroponics nutrient supplying system (no soil-nutrient interaction)
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What Happens to Applied What Happens to Applied Nitrogen Fertilizer?Nitrogen Fertilizer?
What Happens to Applied What Happens to Applied Nitrogen Fertilizer?Nitrogen Fertilizer?
AMMONIUM AMMONIUM FERTILIZERSFERTILIZERS
NITRATENITRATENITROGENNITROGEN
SOIL M ICROORGANISMSSOIL M ICROORGANISMS
SOIL REACTIONSSOIL REACTIONS
AMMONIUMAMMONIUMNITROGENNITROGEN
SOIL ORGANICSOIL ORGANICMATTERMATTER
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What Happens to Applied What Happens to Applied Nitrogen Fertilizer?Nitrogen Fertilizer?
What Happens to Applied What Happens to Applied Nitrogen Fertilizer?Nitrogen Fertilizer?
AMMONIUM AMMONIUM FERTILIZERSFERTILIZERSAMMONIUM AMMONIUM FERTILIZERSFERTILIZERS
NITRATENITROGENNITRATENITROGEN
SOIL MICROORGANISMS
SOIL MICROORGANISMS
SOIL REACTIONSSOIL REACTIONS
AMMONIUMNITROGENAMMONIUMNITROGEN
SOIL ORGANICMATTER
SOIL ORGANICMATTER
CROP UPTAKECROP UPTAKECROP UPTAKECROP UPTAKE
NH3NH3
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Plant Growth and Soil Nutrient Supply RelationshipsPlant Growth and Soil Nutrient Supply Relationships
Wheat response to fertilizer NWheat response to fertilizer N
502 10-year average
0
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0 20 40 60 80 100 120
N Fertilizer (lb/acre)
Yie
ld (
bu
she
ls/a
cre
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Bray mobile nutrient
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Plant Growth and Soil Nutrient Supply Relationships
•Bray
Plant Growth and Soil Nutrient Supply Relationships
•Bray
Soil nutrient supply requirement = Yield X % nutrient in tissueSoil nutrient supply requirement = Yield X % nutrient in tissue
Bushel Wheat Requirement = (lb/bu) * % N = 60 * 2.2 % N (13 % C.P.) = 1.33 lb N/bushel
•Assumes –100 % efficiency in converting soil N to wheat grain N.– relatively constant N content
At 70 % efficiency, requirement is 1.33/.70 = 1.9 lb N/bu
Bushel Wheat Requirement = (lb/bu) * % N = 60 * 2.2 % N (13 % C.P.) = 1.33 lb N/bushel
•Assumes –100 % efficiency in converting soil N to wheat grain N.– relatively constant N content
At 70 % efficiency, requirement is 1.33/.70 = 1.9 lb N/bu
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Plant Growth and Soil Nutrient Supply Relationships
•Bray
Plant Growth and Soil Nutrient Supply Relationships
•Bray
Bushel Wheat Requirement = (lb/bu) * % N = 60 * 2.2 % N (13 % C.P.) = 1.33 lb N/bushel
At 70 % efficiency and 13 % C.P., requirement is 1.33/.70 = 1.9 lb N/bu
At 50 % efficiency and 15 % C.P., requirement is 1.53/.50 = 3.1 lb N/bu
At 100 % efficiency and 11 % C.P., requirement is 1.1/1 = 1.1 lb N/bu
Bushel Wheat Requirement = (lb/bu) * % N = 60 * 2.2 % N (13 % C.P.) = 1.33 lb N/bushel
At 70 % efficiency and 13 % C.P., requirement is 1.33/.70 = 1.9 lb N/bu
At 50 % efficiency and 15 % C.P., requirement is 1.53/.50 = 3.1 lb N/bu
At 100 % efficiency and 11 % C.P., requirement is 1.1/1 = 1.1 lb N/bu
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Fate of Inorganic N in SoilsFate of Inorganic N in Soils
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Nitrogen soil availabilityNitrogen soil availabilityNitrogen soil availabilityNitrogen soil availability
Source and fate of nitrate (NO3
-).Source and fate of nitrate (NO3
-).
NONO33--NONO33--
RainfallRainfall
NONO33--NONO33--
LeachingLeachingLeachingLeaching
NONO33--NONO33--
OO22 + NH + NH44++OO22 + NH + NH44++
NitrificationNitrificationNitrificationNitrification
HH+ + ++HH+ + ++
DenitrificationDenitrificationDenitrificationDenitrification
NN22O and NO and N22NN22O and NO and N22
- O- O22- O- O22
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RainfallRainfall
LeachingLeachingLeachingLeaching
NONO33--NONO33--
DenitrificationDenitrificationDenitrificationDenitrification
NN22O and NO and N22NN22O and NO and N22
- O- O22- O- O22
NONO33--NONO33--
Nitrogen soil availabilityNitrogen soil availabilityNitrogen soil availabilityNitrogen soil availability
Source and fate of ammonium (NH4
+).Source and fate of ammonium (NH4
+).
CEC (-)CEC (-)CEC (-)CEC (-)
NHNH44++NHNH44++
Soil OrganicSoil OrganicMatter-NMatter-NSoil OrganicSoil OrganicMatter-NMatter-N
MineralizationMineralizationMineralizationMineralization
++OHOH--
++OHOH--
NHNH3 3 + + HH22OONHNH3 3 + + HH22OO
HH+ + ++HH+ + ++NONO33
--NONO33--
NONO33--NONO33--
OO22 + +OO22 + +
VolatilizationVolatilizationVolatilizationVolatilization
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RainfallRainfall
LeachingLeachingLeachingLeaching
NONO33--NONO33--
DenitrificationDenitrificationDenitrificationDenitrification
NN22O and NO and N22NN22O and NO and N22
- O- O22- O- O22
NONO33--NONO33--
Nitrogen soil availabilityNitrogen soil availabilityNitrogen soil availabilityNitrogen soil availability
Source and fate of ammonium (NH4
+)Source and fate of ammonium (NH4
+)
CEC (-)CEC (-)CEC (-)CEC (-)
MineralizationMineralizationMineralizationMineralization
++OHOH--
++OHOH--
NHNH3 3 + + HH22OONHNH3 3 + + HH22OO
HH+ + ++HH+ + ++OO22 + +OO22 + +
VolatilizationVolatilizationVolatilizationVolatilization
Soil OrganicSoil OrganicMatter-NMatter-NSoil OrganicSoil OrganicMatter-NMatter-N
NHNH33NHNH33
NONO33--NONO33--
NONO33--NONO33--
NHNH44++NHNH44++
immobilizationimmobilizationimmobilizationimmobilization
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Plant Growth and Soil Nutrient Supply Relationships
•Bray –Current Oklahoma field practice
Plant Growth and Soil Nutrient Supply Relationships
•Bray –Current Oklahoma field practice
Estimated yield in bu/acre (YG) * 2 lb N/bu =Estimated N requirement
Estimated N requirement - soil test NO3-N =Fertilizer N requirement.
Estimated topdress N = est.(Yield * %N) - preplant and soil N supplied
–sensor based goalEstimated topdress N =k sensed yield and
sensed % N
Estimated yield in bu/acre (YG) * 2 lb N/bu =Estimated N requirement
Estimated N requirement - soil test NO3-N =Fertilizer N requirement.
Estimated topdress N = est.(Yield * %N) - preplant and soil N supplied
–sensor based goalEstimated topdress N =k sensed yield and
sensed % N
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Plant Growth and Soil Nutrient Supply RelationshipsPlant Growth and Soil Nutrient Supply RelationshipsN use efficiency = [100 (Nx - N0) grain N] / Nx appliedN use efficiency = [100 (Nx - N0) grain N] / Nx applied
Lahoma 502, 30-yr Averages
0
10
20
30
40
50
0 20 40 60 80 100 120N Rate (lb/acre)
Whe
at Y
ield
(b
u/ac
re)
0
10
20
30
40
50
NU
E (%
)
Yield NUE
Lahoma 502, 30-yr Averages
0
10
20
30
40
50
0 20 40 60 80 100 120N Rate (lb/acre)
Whe
at Y
ield
(b
u/ac
re)
0
10
20
30
40
50
NU
E (%
)
Yield NUE