integrated nutrient management section r swes 316
TRANSCRIPT
Integrated Nutrient Management
Section R
SWES 316
What is Integrated NM?
¨ Considering more than just yield-limiting factors when managing nutrients.
¨ Simultaneous consideration of:– Factors affecting crop yield– Factors affecting crop quality– Economic factors– Environmental factors– “System” factors
The Goals of Nutrient Management are to…¨ Optimize plant production
– Yield/quality– Profit
¨ Conserve resources¨ Enhance soil quality and productivity
Why Integrated NM?
¨ One cannot manage nutrients in isolation from other factors. Nutrients must be managed as a part of a cropping system because:– Other factors controlling plant growth will
also affect nutrient demand and nutrient fate.
Crop-Related Factors
¨ Growth rate (phenology)
¨ Nutrient uptake rate¨ Salt tolerance¨ Heat tolerance¨ pH tolerance¨ Is the crop harvested,
all or part?¨ Water consumptive
use
¨ Unique nutrient needs¨ Root system depth and distribution¨ Tissue test levels throughout growing season¨ Yield potential¨ Yield¨ Soil temp requirement¨ Insect infestation
Soil-Related Factors¨ Chemical/Biological:
– EC (salt)– SAR (sodium)– CEC– Antecedent plant-
available nutrients– pH– OM content– CaCO3 content– Mineralizable N (SOM)– Disease history
¨ Physical:– Texture– Water-holding capacity– Structure/restrictive layers– Soil Depth
¨ Other– Soil management history– Soil variability
Weather-Related Factors
¨ Annual rainfall/relation to crop C.U.¨ Annual rainfall distribution¨ Climate:
– Average air/soil temperatures during the year– Heat unit accumulations
Irrigation Factors¨ Water pH¨ Water ECw
¨ Water SAR¨ Water SO4
2-, Cl-, HCO3-, CO3
2- , H3BO3, Na+, Ca2+, Mg2+
¨ Availability/cost of water¨ Crop leaching requirement¨ Irrigation system: type of system, capabilities wrt
amount of water, frequency, uniformity
Fertilizer Factors
¨ Equipment availability for fertilizer application¨ Irrigation system capabilities¨ Inorganic or organic fertilizer?¨ If organic, need the mineralization rate¨ Compatibility of fertilizers with soil/water¨ If CRF, need release rate¨ Fertilizer costs¨ Is the fertilizer solid, liquid, gas? Mobile or
immobile? Acid or alkaline?
Summary
¨ Based upon these lists, we have counted at least 75 different pieces of information that will be needed to make wise, informed decisions about nutrient management.
¨ Where does the information come from?– Grower Experience– Published scientific information– State Extension services (Land Grant Univ.)– Private sector - commercial enterprises
Crop Factors
Corn Phenology Source: Iowa State University
Corn K Uptake Source: Iowa State University
Broccoli N Uptake
A
B
0
1
2
3
4
5
6
0 50 100 150
Days After Planting
Dai
ly N
Flu
x (k
g ha
-1 d
ay-1)
1993-94
1995-96
0
50
100
150
200
250
300
350
0 50 100 150
Days After Planting
To
tal
N U
pta
ke
(kg
ha-1
)
1993-94
1995-96
20
40
60
80
100
0 2 4 6
Soil EC
% Y
ield Lettuce
Broccoli
Cantaloupe
Sweet Corn
EC and Crop Growth
“Non-saline” “Saline”
NO3-N in Broccoli Petiole Sap
0
200
400
600
800
1000
1200
1400
1600
4-6 Leaf 10-12 Leaf First Buds HeadDevelopment
Pre-Harvest
NO
3-N
in S
ap (m
g/L)
Excessive
Adequate
Warning
Deficient
Malting Barley - Response to N
R2 = 0.9943R2 = 0.8426
0
500
1000
1500
2000
2500
3000
3500
4000
0 50 100 150 200 250 300
N Applied (lb/ac)
Yie
ld (
lb/a
c) Crystal 1997
Crystal 1998Yield
Quality
Good Irrigation Management is EssentialSource: Paul Brown, UA
Soil Factors
Soil Test Guidelines for Cantaloupes
If preplant soil NO3-N is:
0-5 ppm add 50-75 lb N/acre6-10 ppm add 50 lb N/acre>10 ppm add 0-50 lb N/acre
If preplant soil P (HCO3 method) is:
<5 ppm add 40-100 lb P2O5/acre5-15 ppm add 0-40 lb P2O5/acre >15 ppm add 0 lb P2O5/acre
Variability of Salinity in Soil
In this case, saltmanagement, notnutrients, may bethe key to cropproductivity.
Soil Salinity August 2003
0 10 20 30 40 50 60
0-3 in
0-1 in
0-0.5 in
Soil
EC (d
S/m
) Furrow
40" Low F
80" Low F
40" High F
80" High F
Soil ECe(dS/m)
After germination irrigation
Irrigation/Water/Weather Factors
Leaching Requirement for Pecans
0
5
10
15
20
25
0 500 1000 1500
Irrigation Water Salinity (ppm)
Lea
chin
g R
equi
rem
ent
(%)
Timing and amountof leaching irrigationshould be consideredwhen managingfertilizer.
Ensure fertilizer compatibilitywith water, and with otherinjected chemicals in pressurized irrigation systems.
Compatibility will dependon water pH, HCO3
-, Ca2+,EC, etc.
Fertilizer Factors
Organic Fertilizers
Fertilizer Prices
Material $/ton $/#N$/#S
Gypsum 40 NA 0.11Sulfuric acid 80(soil) NA 0.12Sulfur 250 NA 0.14Nitro-Sul 250 0.63
0.31Thio-Sul 190 0.79
0.36N-Phuric 190 0.63
0.59UAN-32 185 0.29
NA
Example: Integrated Nutrient Management for Cotton in Arizona
Courtesy of J.C. Silvertooth
Key Tools for Managing N in Cotton
¨ Use split applications¨ Follow crop development/N needs
– % Fruit Retention (FR)– Height to Node Ratio (HNR)– Petiole NO3-N concentrations (PN)
¨ Remember importance of avoiding excess N because of negative influence on reproductive performance of the plant.
Generalized Flower Curve
Heat Units Accumulated After Planting
Nu
mb
er
of
Fresh
Blo
om
s
Pinhead Square Peak Bloom
Cut-out
Possible N Management Approaches
¨ Scheduled fertilization based upon either– stage of growth or calendar dates
¨ Feedback approach (recommended)– crop condition (HNR, FR, PN)– Interpretation of feedback depends on stage of
growth (HUAP)– reference to established baselines
Feedback Management Requirements
¨ Useable / accessible measurement¨ Established baselines / guidelines
– reference base¨ Common variety types (species)¨ Regionally specific baselines¨ Validation of recommendations
Optimal N Management
¨ Provides for optimal N efficiencies– agronomically (crop response)– economically– environmentally
¨ Improved fertilizer N efficiency– better fertilizer N recoveries
¨ Reduced leaching losses
Steps for Optimal N Management
1. Establish a realistic yield goal
2. Account for soil and irrigation water available N
3. Split N applications
4. Follow crop conditions throughout the growing season and adjust N application accordingly
Optimal N Management (Step 1)
¨ Use realistic yield goal– 60 lbs N/bale
• Unruh, B.L. and J.C. Silvertooth. 1996– Upland and Pima, Arizona
• Mullins, G.L. and C.H. Burmester. 1990.– Upland, Alabama
– sets upper limit for crop N needs• assumes high N fertilizer efficiency
Optimal N Management (Step 2)
¨ Account for residual soil NH4-N and NO3-N– Each 1 ppm NH4-N or NO3-N in the top 12
inches of soil equals about 4 lb N/ac of available N
¨ Account for irrigation water NO3- - N
• 2.7 X ppm NO3- -N = lbs N/acre ft water
¨ Subtract these values from total N needs
Optimal N Management (Step 3)
¨ Split N fertilizer applications– follow crop condition (HNR, FR, petiole
concentration)– window = PHS - PB (600 - 2000 HUAP)
¨ Avoid preseason N applications if possible
N Application Window
Heat Units Accumulated After Planting
Nu
mb
er
of
Fresh
Blo
om
sPinhead Square Peak Bloom
Cut-out
Split N Applications
Optimal N Management (Step 4)
¨ Monitor Crop Condition:– Fruit Retention (FR)
• Yield potential is generally related to fruit retention. Lower fruit retention, especially late in the season means lower yield potential.
– Height to Node Ratio (HNR)• HNR is related to vegetative/reproductive balance.
Higher-than-normal values mean excessively vegetative plants, so N application should be delayed.
– Petiole NO3-N• A direct measure of plant N status
Optimal N Management Example
¨ 3 bale yield goal X 60 lbs N/bale = 180 lbs N/acre (estimate of upper N fertilizer rate)
¨ Subtract residual soil and irrigation water N– Ex. 15 ppm NO3
- -N residual/top 12 in = 60 lbs N
¨ Subtract water NO3-N– Ex. 5 ppm NO3-N x 4 ac ft/ac = 54 lbs N
¨ 180 – 60 – 54 = 66 lbs N minimum¨ Add 20% to allow for inefficiency = 80 lbs N¨ Split in 3-4 applications (PHS-PB)
N Management Irrigated Cotton
¨ First application at PHS– approximately 50 lbs N/acre
¨ Irrigate/cultivate¨ Second application near FB
– evaluate crop condition (FR, HNR, petioles)¨ Irrigate/cultivate¨ Third application before PB
– evaluate crop condition (FR, HNR, petioles)
HNR Baselines
Heat Units Accumulated After Planting
500 1000 1500 2000 2500 3000 3500
Hei
gh
t (i
n.)
/No
de
Ra
tio
0.0
0.5
1.0
1.5
2.0
2.5
FR Baselines
Heat Units Accumulated After Planting
500 1000 1500 2000 2500 3000 3500
% F
ruit
Ret
enti
on
0
20
40
60
80
100
120
Petiole NO3--N Concentration
Baselines
Heat Units Accumulated After Planting
500 1000 1500 2000 2500 3000 3500
Pet
iole
NO
3- -N (
pp
m x
100
0)
0
5
10
15
20
25
30
Excess
Adequate
Deficient
Warning
Crop Monitoring - N Management
Heat Units Accumulated After Planting
500 1000 1500 2000 2500 3000 3500
% F
ruit
Ret
enti
on
0
20
40
60
80
100
120
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Heat Units Accumulated After Planting
500 1000 1500 2000 2500 3000 3500
Hei
gh
t (i
n.)
/No
de
Ra
tio
0.0
0.5
1.0
1.5
2.0
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Crop Monitoring
¨ Case 1– High fruit load (high fruit retention)
• HNR within thresholds • N input needed• If decline in petiole NO3
--N is observed– provide application of N fertilizer
Heat Units Accumulated After Planting
500 1000 1500 2000 2500 3000 3500
% F
ruit
Ret
enti
on
0
20
40
60
80
100
120
[1]
[1][1]
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Heat Units Accumulated After Planting
500 1000 1500 2000 2500 3000 3500
Hei
gh
t (i
n.)
/No
de
Ra
tio
0.0
0.5
1.0
1.5
2.0
2.5
[1]
[1]
[1] [1] [1] [1]
[2]
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Crop Monitoring
¨ Case 2– Low fruit load (low fruit retention)
• HNR is high (relative to guidelines)– hold back or reduce N fertilizer inputs– consider Pix application
Heat Units Accumulated After Planting
500 1000 1500 2000 2500 3000 3500
% F
ruit
Ret
enti
on
0
20
40
60
80
100
120
[1]
[1][1]
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Heat Units Accumulated After Planting
500 1000 1500 2000 2500 3000 3500
Hei
gh
t (i
n.)
/No
de
Ra
tio
0.0
0.5
1.0
1.5
2.0
2.5
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[1]
[1] [1] [1] [1]
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Crop Monitoring¨ Case 3
– HNR is low (relative to guidelines)• maintain N fertilizer inputs• Pix is not needed
– Crop is experiencing some form of stress• water, N, salinity, etc.
– limiting growth
– Identify and correct
Heat Units Accumulated After Planting
500 1000 1500 2000 2500 3000 3500
% F
ruit
Ret
enti
on
0
20
40
60
80
100
120
[1]
[1][1]
[1][1]
[1]
[2]
[2]
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[2][2]
[2]
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Heat Units Accumulated After Planting
500 1000 1500 2000 2500 3000 3500
Hei
gh
t (i
n.)
/No
de
Ra
tio
0.0
0.5
1.0
1.5
2.0
2.5
[1]
[1]
[1] [1] [1] [1]
[2]
[2]
[2][2]
[2][2]
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