Irrigation and Nitrogen Management Web‐Based Software for Lettuce ProductionWeb Based Software for Lettuce Production

Michael CahnIrrigation and Water Resources AdvisorUniversity of California, Cooperative, Monterey Co

Acknowledgements

California Department of Food and AgricultureCalifornia Department of Food and Agriculture, Fertilizer Research  and Education ProgramUC ANR Communication ServicesUC ANR Communication ServicesGrower participantsChiquita FreshExpressChiquita FreshExpress

Nitrate is part of CA Central Coast Agricultural Water Quality Regulations

regulatory compliance will require management changesregulatory compliance will require management changesuse nitrogen fertilizer more efficientlyaccount for all sources contributing to crop uptake of Nimprove irrigation managementrecord keeping and reportingdocument improvements in water qualitydocument improvements in water quality

Tools for Managing Water and Nitrogen F ili i LFertilizer in Lettuce

Quick nitrate soil test  (20 NO N 70 80 lb f N/ /f )(20 ppm NO3‐N = 70 to 80 lbs of  N/acre/ft) 

Weather‐based irrigation scheduling

Commercial Lettuce Nitrogen Fertilizer Trials

300

Standard BMP

200

250

Lbs N/A212

Difference 66 lbs/A

150lbs

N/A

146

66 lbs/A

@ 0.60/lb N$40/A

50

100=$40/A

0

50

1 2 3 4 5 6 Ave1 2 3 4 5 6 AveField

Commercial Yield

1000

1200

97% of G

800

1000

e

Grower

600

xes/

Acr

e

GRBMP

200

400

Box

BMP

01 2 3 4 5 Avg

FieldField

Applied Water as Percentage of Crop ET (Lettuce)

) 300

350Crop ET (Lettuce)

Cro

p ET

)

250

300 Avg Applied Water = 176% of Crop ET

ater

(% C

150

200

pplie

d W

a

100

150

Ap

0

50

Field Number

1 3 5 7 9 11 13 15 17 19

I i ti T i l i L ttIrrigation Trials in Lettuce

WeatherStandard BMP

Estimated Crop ETc 

Irrigation 

requirement 1 Water use reduction  Total Applied Water 

- based

Trial Sitep

(inches)q(inches) (%)

King City 17.7 14.7 10.1 13.4 17S. Salinas 9.9 8.7 7.6 8.9 12

pp(inches)

San Ardo 19.4 11.9 6.7 8.7 39N. Salinas 10.7 10.4 7.0 8.4 3S. Salinas 2 10.9 10.1 6.1 7.6 7

Average 13.7 11.2 7.5 9.4 16

1. Irrigation requirement = ETc/distribution uniformity

Weather‐based Irrigation Scheduling

Converting Reference ET to Crop ET:

ETcrop = ETref Kcrop

Kc can vary from 0.1 to 1.2

CIMIS weather networkCIMIS weather network

29 DAP 41 DAP

1.0sprinkler irrigation events

Estimated Kc of Lettuceie

nt (K

c)

0 6

0.8

47 DAP 65 DAP

op C

oeffi

c

0.4

0.6

SprinklerDrip

Cro

0.0

0.2 Average Kc = 0.33 during germination with sprinklers

Days after Planting

0 20 40 60 80

Other factors for determining an irrigation g gschedule:

Soil water holding capacityCrop rooting depthIrrigation system application rateIrrigation system application uniformity

hi f i ( li i )Leaching fraction (water salinity)Crop development stage

How can water and N management tools be useful for large vegetable growing operations?useful for large vegetable growing operations?

Large growing operations have multiple decision makersmakers One farm manager may be responsible for >200 fields during a seasonfields during a seasonOther responsibilities besides water and fertilizer N managementN management

Web‐based Irrigation and N management  software for lettuce

https://ucanr.org/cropmanage

CropManage Web‐based Tool:Assist growers in making decisions on irrigation and nitrogen fertilizer management

Intuitive, simple, quick to use.Accessible from smart phone, tablet computer,Accessible from smart phone, tablet computer, desktop computerGuide irrigation schedules using CIMIS weatherGuide irrigation schedules using CIMIS weather data. Guide nitrogen fertilization decisions using quickGuide nitrogen fertilization decisions using quick nitrate test data.Maintain and share irrigation, fertilizer, and soilMaintain and share irrigation, fertilizer, and soil test records for multiple fields and farms.

Integrate information from multiple sources

Soil and Ranch base info Crop ET model Watering Recommendation

Database driven web 

CIMIS EToCrop N model

Recommendation

N fertilizer 

applicationSoil nitrate test

Recom‐mendation

Record display and data export

Field sensors

data export

Decision support using crop models

How is N fertilizer rate determinedHow is N fertilizer rate determined from the quick nitrate test?

Future Crop N uptakeFertilizer N Rate = Future Crop N uptake

– (Quick Test N  ‐ threshold NO3‐N) 

Fertilizer N Rate 

– predicted soil mineralization N 

– predicted plant residue N

100100Iceberg lettuce canopy cover

over

(%)

60

80

over

(%)

60

80

Can

opy

Co

20

40

Can

opy

Co

20

40

Days after Planting

0 10 20 30 40 50 60 700

Days after Planting

0 10 20 30 40 50 60 700

%)

100

Canopy b = 1 01 x Canopy d 0 69%)

100

Canopy b = 1 01 x Canopy d 0 69

anop

y C

over

(%60

80 Canopyobs = 1.01 x Canopypred - 0.69

R2=0.99an

opy

Cov

er (%

60

80 Canopyobs = 1.01 x Canopypred - 0.69

R2=0.99O

bser

ved

Ca

20

40

Obs

erve

d C

a

20

40

Predicted Canopy Cover (%)

0 20 40 60 80 1000

Predicted Canopy Cover (%)

0 20 40 60 80 1000

Available moisture depends on soil type and rooting depthg p

0Rooting Depth of Lettuce(in

ches

)

10

otin

g D

epth

20

Roo

30

Days after Planting0 10 20 30 40 50 60 70 80

Spatial CIMIS ETo Reporting

How much water was applied?

Evaluate and document water management

s) 12

water managementr (

inch

es

10

12

CropManage RecommendationGrower Application

ed W

ater

6

8

ve A

pplie

4

6

Cum

ulat

iv

0

2

Days after Planting

0 10 20 30 40 50 60

C

Soil Summary

Fertilizer Summary

Watering Summary Table

Field Validation of CropManage

TreatmentApplied N Fertilizer

Commercial Yield

lb    ‐‐‐‐‐‐‐ lbs per acre ‐‐‐‐‐‐‐‐CropManage 149 18760Grower Standard 211 19114Grower Standard 211 19114

The road ahead…

Interface with UCD online Soil Survey Tool

Soil moisture monitoring

s)

0

sion

(cba

rs10

oist

ure

tens

20

8 inches

soil

mo 30

40

8 inches18 inches

Date

9-16 9-18 9-20 9-22 9-24 9-26 9-28 9-30 40

Final Thoughts

Web‐based applications can integrate complex data and models  into simple to use decision support tools

CropManage is not just for growers.  It is a potential tool for crop consultants to use in assisting growers withfor crop consultants  to use in assisting growers with water and N management decisions.

We will offer training workshops on CropManage beginning March 2013.