Advances in Pistachio Irrigation WorkshopMay 30, 2018 – Harris Ranch, Coalinga, CA

Updated Information on Pistachio Water Requirements in the S.J.V.

Daniele Zaccaria, Ph.D.Agricultural Water Management Specialist, UC Cooperative Extension

Ph.: (530) 219-7502 Email: dzaccaria@ucdavis.edu

WORK IN PROGRESS &

TEAM-EFFORTPARTNERS: B. Sanden, R. Snyder, B. Lampinen, L. Ferguson, S. Grattan, K. Bali, M. Culumber (UC CE), M. Whiting, S. Ustin, K. T. Paw U (UC Davis), C. Little (DWR), D. Corwin & E. Scudiero (USDA Salinity Lab, Riverside)

SCHOLARS & VISITING FACULTY: Giulia Marino, Kristen Shapiro, Mahesh Maskey (UC Davis), Camilo Souto & Octavio Lagos (Univ. of Concepion, Chile)

COLLABORATORS: J. Nichols, B. Flores, Z & J. Sheely, J. Gebhardt

TECHNOLOGY: Tule Technologies, Terravion, Ceres Imaging, Phytec.

FUNDING AGENCIES: CPRB, CDFA-SCBP, ANR Start-up Funds

WHAT DRIVES CROP EVAPOTRANSPIRATION (ET)?

T

H

G

E

How much energy is being used to evaporate or transpire water? 

LE

How much energy is being used to evaporate or transpire water? 

Shortwave Radiation+

Longwave RadiationEnergy used to heat the air or canopy

Energy conducted into or out of the ground

LEHRn

G

OUR HYPOTHESISLower osmotic potential of saline soils reduces:

EC = 4-5 dS/mLight intercep. = 65%

EC = 6-8 dS/mLight intercep. = 40%

EC = 8-11 dS/mLight intercep. = 25%

Tree canopy growth (size & density) Light interception by the canopy Evapotranspiration (ET) Ability of trees to extract water from soil Crop yield

All orchards are Kerman cv. on PG1 rootstock

Study Orchards

2015-2016-2017

NICHOLSFLORES & SHEELY

2018

GEBHARDT

CHARACTERISTICS OF THE STUDY ORCHARDS

Canopy cover: 75% Canopy cover: 45-50%ECe: ~ 2 dS/m ECe: ~ 2 dS/m

NICHOLS – S0 NICHOLS – S050%

Canopy cover: 65%ECe: 2-7 dS/m

Canopy cover: 20-55%ECe: 2-11 dS/m

SHEELY – S1 FLORES – S1, S2, S3

ACTIVITIES CONDUCTED IN 2016 & 2017

Measured ET at 12 stations and calculated Kc values.

Captured the variations of ET as related to differences in canopy cover and light interception among and within orchards

Measured PAR Light Interception, Canopy Area and Vegetation Indices on multiple dates with the UC Mule Light Bar and Airborne Remote Sensing flight overpasses

Monitored Plant Water Status with Midday Stem Water Potential, Dendrometers.

Monitored Soil Moisture Status with Watermarks and Tensiometers

Conducted the E.M. survey on the footprint areas of the 12 ET stations to characterize the Soil-water Salinity and its relationships with Canopy Cover & actual ET

Measured additional parameters (canopy & vegetation, trunk diameter, crop yield and quality)

Nichols ~ 75% Nichols ~ 45%

Sheely ~ 65%

Photosynthetic Radiation Intercepted by the Tree Canopy

Flores 25-55%FLORES

SEASONAL CUMULATED ET1. Non salt-affected (S0) mature orchards (~72-75% canopy cover)

have seasonal ET of about 36-40 inches (May-October)2. Salt-affected orchards (S1, S2, S3) have significantly lower ET

(30-50%) than non salt-affected orchards, depending on salinity level and tree vigor

2016

2017

ACTUAL ET ALONG THE CROP SEASON

Salt-affected orchards have consistently lower ET (30-50%)than non salt-affected orchards, depending on the level of salinity

2016

2017

Similar trends observed between the crop season 2016 and 2017

We found that the non salt-affected orchards have Kc values ~20-30% lower than those commonly used by growers to schedule irrigation

Kc values from previous UC study in 2005 for sprinkler-irrigated pistachio

Salt-affected orchards have lower Kc than the non salt-effected

S0

S1S2S3

S050%

2017

2016S0

S1

S2S3

Differences of Kc values bw. our study and earlier UC studies:

#) different irrigation methods#) different ET estimation methods#) improved accuracy of ETo

CROP COEFFICIENTS (Kc)

COMPARISON OF UC Kc VALUES WITH OTHER STUDIES

There is a good correlation between cumulated ET and PAR light interception (trees’ vigor) in 2016 and 2017

2016: r2 = 0.782017: r2 = 0.76

~ 45% CC ~ 45% CC

NON SALT-AFFECTED SALT-AFFECTED

Monitoring Soil Moisture (Tension)

WHAT WE LEARNED SO FAR

Salinity affects tree water uptake and evapotranspiration by three main mechanisms:

Salinity reduces plant growth, canopy size & density, resulting in less light interception and thus in less crop transpiration

Salinity decreases the soil osmotic potential resulting in less water extraction and probably lower stomatal conductance, thus in less crop transpiration fluxes

In salt-affected orchards more sunlight (energy) reaches the soil causing more soil evaporation (if soil is wet) => Soil evaporation can be a significant avoidable water loss (non beneficial water use)

QUESTIONS??