Michael Cahn Irrigation and Water Resources Advisor UC ...
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Strategies for Managing Nitrogen in Strawberry Michael Cahn Irrigation and Water Resources Advisor UC Cooperative Extension, Monterey County
Transcript of Michael Cahn Irrigation and Water Resources Advisor UC ...
Strategies for Managing Nitrogen in Strawberry
Michael CahnIrrigation and Water Resources AdvisorUC Cooperative Extension, Monterey County
Acknowledgements:
• Tim Hartz, UC Davis• Tom Bottoms, Dellavalle Laboratory• Mark Bolda, UCCE Santa Cruz• Andre Biscaro, UCCE Ventura• Oleg Daugovish, UCCE Ventura• Surendra Dara, UCCE San Luis Obispo• Mark Gaskell, UCCE San Luis Obispo• Emily Gardner, Driscolls
Nitrogen Use Reporting
Developing a Nitrogen Fertilization Plan For Strawberry
1. Crop N demand: • Estimate crop nitrogen requirement
2. Nitrogen supply:• Residual mineral N (nitrate and ammonium in soil) • Potential soil mineralization (organic matter, residue,
amendments)• Irrigation water• Fertilizer
3. Tools to guide fertilizer scheduling:• Soil sample• Tissue analysis• Suction lysimeter
Seasonal applied N fertilizer (lbs N/acre)
50 100 150 200 250 300 350
Mark
eta
ble
Fru
it Y
ield
(lb
s/a
cre
)
20000
40000
60000
80000
100000
120000
Observation: Marketable fruit yield is not correlated with seasonal applied N fertilizer
• Fields can have high yields with low rates of N fertilizer• Applied N can be much lower than the amount of N that
the crop takes up
Seasonal Nitrogen Fertilizer Applied in Strawberry (Salinas/Watsonville 2017)
Field
1 2 3 4 5 6 7 8 9 10 11 12 13 14
App
lied N
(lb
s N
/acre
)
0
50
100
150
200
250
300
350
Preplant Fertigated
Seasonal Nitrogen Fertilizer Applied in Strawberry (Salinas/Watsonville 2017)
✓ Fertilizer programs are often similar among fields within the same grower operation
✓ Reliance on preplant fertilizer
Fruit Yield (lbs/acre)
0 20000 40000 60000 80000
Fru
it N
up
take lb
s N
/acre
0
50
100
150
200
250
N uptake = 2 x fruit yield/1000 -1.65
R2 = 0.95
1000 lbs of fruit take up about 2 lbs of N per acre
Field Number
1 2 3 4 5 6 7 8 9 10 11
Cro
p N
upta
ke (
lbs N
/acre
)
0
50
100
150
200
250
300
350
vegetation N fruit N
About Half of the Crop Nitrogen is in the Fruit
Crop N needs can be estimated from fruit yield
Fruit Yield (lbs/acre)
0 20000 40000 60000 80000
Cro
p N
up
take
(ve
ge
tatio
n +
fru
it)
lb
s/a
cre
0
100
200
300
400
N uptake = 20.3 + 3.3 x fruit yield/1000
R2 = 0.93
Days after Planting
100 150 200 250
Cro
p N
upta
ke (
lbs N
/acre
)
0
50
100
150
200
Crop Nitrogen Uptake Pattern in Strawberry
N uptake = 1 to 1.5 lbs N/acre/day
Previous Crop Residues
Potentially mineralize 30 to 60 lbs N/acre
Organic Amendments
Soil Nitrogen Mineralization
Soil
% Organic
Matter
Estimated N
mineralization
(lbs N/acre/day)
Placentia sandy loam 0.9 0.5
Chualar loam 1.2 0.7
Cropley silty clay 1.3 0.9
Metz fine sandy loam 1.4 0.6
Mocho silty clay loam 2.0 1.0
Nitrogen available in irrigation water
Well water(2 to 70 ppm Nitrate-N)
Recycled water(15 to 30 ppm N as Ammonium + Nitrate)
Calculating N applied from irrigation water:
Applied water (inches) x NO3-N conc. (ppm) x 0.227
= lbs N/acre
✓Applied water = 1.1 inch per week✓Nitrate-N concentration = 20 ppm
1.1 inches/week x 20 ppm NO3-N x 0.227
= 5.0 lbs N/acre/week
Example:
Soil Nitrate Quick Test
• Sample 0 – 1 foot zone just outside of plant row• Angle probe slightly towards the center of bed• Composite soil from > 10 locations
Jan 01 Mar 02 May 01 Jun 30 Aug 29
So
il N
O3-N
(p
pm
)
0
5
10
15
20
25
30
Cro
p N
up
take
(lb
s N
/acre
)
0
50
100
150
200
What is a sufficient soil nitrate-N concentration forstrawberry?
30 lb N/acre/month
Soil N threshold
• 10 to 15 ppm Nitrate-N adequate in early season (40 to60 lbs N/acre)
• Many productive fields have soilnitrate levels < 10 ppm N duringthe main fruiting period
Treatment
Applied
Water
Seasonal N
fertilizer
Average
soil nitrate
Marketable
Yield
inches lbs N/acre ppm N lbs fruit/acre
70% Crop ET 18 240 28 80159 A
100% Crop ET 26 240 15 83910 A B
130% Crop ET 32 240 14 92000 B
Grower Standard 36 266 3 81956 A
Irrigation management affects soil nitrate levels
(2016 Watsonville Trial)
* Treatments with similar letters are not statistically different at the 95% confidence level.
*
• Values from high yielding, nutritionally balanced fields
• Composite of 30 recently mature leaves
DRIS leaf ‘optimum ranges’
peak
harvest
early
flowering
}
1 2 3 4 5
Crop StageBottoms et al. 2013
CropManage: Online irrigation and nitrogen management decision support tool
v3.cropmanage.ucanr.edu
How useful are suction lysimeters for monitoring crop N status?
• Highly variable concentrations of nitrate in leachate
• Concentration is affected by irrigation (leaching fraction)
Is preplant fertilizer necessary?
How effectively is preplant CRF being used ?▪ Most common product is 18-8-13, 6-8 month release
Documenting N release rate from CRF:
▪ CRF bags buried in two strawberry fields in mid-November▪ 3 bags recovered from each field each month,
and analyzed for the amount of N remaining in the prills
(Hartz and Bottoms 2011)
When CRF was applied in November, 70-80% N release by April 1
N release was nearly linear over time :
Controlled Release Fertilizer Trial(Crop N uptake by the end of April)
Nitrate leaching usually occurs during the winter
Photo: S. Koike
Salt burn due to proximity roots to preplant fertilizer band
Summary▪Strawberry N uptake is 20 to 30 lbs N/acre during the winter and about 1 to 1.5 lbs N/acre/day after March
▪Other sources of N (residual soil N, soil mineralization, irrigation water) may supply much of the N needs of a strawberry crop besides fertilizer
▪A combination of soil and whole leaf sampling can help with decision making on N rates
▪Irrigation needs to be optimized
