Pomegranate fertigation and Nitrogen Use …Pomegranate Water Applied, Precipitation & Eto 0 100 200 300 400 500 600 700 800 900 1000 4/23 5/13 6/2 6/22 7/12 8/1 8/21 9/10 9/30 10/2

Claude J. Phene, James A. Ayars, R. Scott Johnson, Gary S. Banuelos,

Rebecca C. Phene, Dong Wang, Kevin Day & Rick Schoneman

Pomegranate Irrigation, Fertigation and Nitrogen

Use Efficiency with Drip Irrigation

The ONLY WAY (???) to Irrigate

Reduce or eliminate runoff

Reduce evaporation from soil & plant surfaces

Reduce drainage below the root zone

Overcome soil surface infiltration variability

Optimize Irrigation scheduling

Optimize Irrigation application uniformity

Optimize Fertigation management

Decreasing Water Applied for Irrigation

Without Yield Reduction Depends

Mostly on the Irrigation System ability to:

Research Objectives

The overall objective is to optimize water-nitrogen interactions to improve N-use efficiency (NUE) of Pomegranate and minimize N leaching losses

a. Determine the seasonal N requirement of DI- and

SDI-fertigated Pomegranate that improve NUE without yield reduction.

b. Determine the effect of three rates of real time N-fertigation of pomegranate with DI and SDI on N leaching losses.

c. Determine if concentrations of macro-, micro-nutrients and healthy bioactive compounds in soil, peel and fruits are influenced by rates of real time N-fertigation of pomegranate with DI and SDI.

Randomized Complete Block

Design with Subsamples

Surface Drip

Subsurface Drip

50% N

100% N

150% N

Orchard Layout & Design

Five Replications

3.54 acres

18 x 12 ft. spacing

Nitrogen Treatments

Irrigation Treatments

Installation of Subsurface Drip Irrigation (SDI) Line at 2 Feet Depth

6 ft. spacing, 2 ft. Depth

N-pHURIC K2T

Phos Acid

AN-20

Sand Media Filter

Lysimeter Solution Refill Tank

pH & Ecw meters

N1 SDI DI

N2 SDI DI

N3 SDI DI

Electro-Magnetic Flow Meters

To Lysimeter Refill Tank

Solenoid Valve

Vacuum Relief Valve

Pressure Gauge & Transducer

Submain Lines to Orchard @ 4.0-ft. depth

Manifold inlet including flush valve, pressure gauge & vacuum relief valve

Computerized Control System Linked

To Real Time ETc on Lysimeter

Control System

799 Pomegranate trees (Pom Wonderful) planted on April 28, 2010

Trees irrigated manually by tanking weekly or as needed in 2010

Weighing lysimeter (13.12 x 6.56 x 6.56 ft.) resolution of 0.002 in. of evapotranspiration

Soil NO3-N, all plots, 4/2011

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

55.0

60.0

65.0

70.0

0-6 6-12 12-18 18-24 24-30 30-36 36-48 48-60 60-72 72-84 84-91

Soil depth, in.

Soil N

O3-N

, p

pm

Mean N1-DI NO3-N, mg/l Mean N1-SDI NO3-N, mg/l Mean N2-DI NO3-N, mg/l

Mean N2-SDI NO3-N, mg/l Mean N3-DI NO3-N, mg/l Mean N3-SDI NO3-N, mg/l

0

10

20

30

40

50

60

4/28/2007 5/18/2007 6/7/2007 6/27/2007 7/17/2007 8/6/2007

Nit

rate-N

. p

pm

Date 2011

Mean Tissue Nitrate-N Recovery

N1,SDI N1,DI N2,SDI N2,DI N3,SDI N3,DI MEANS

AN-20 Fertilizer

injected at

5.8 lb N/ac./irrigation

with 10 irrigations

from 6/17-6/24

Applied Fertilizers

Fertilizers H2SO4 H3PO4 AN-20 K2T

Elements S PO4-P N K

Concentration, ppm 6<pH<6.5 20 55 50

Amount Applied, lb/ac 632 26.3 58 53

NOTE: All liquid fertilizers were applied by injection into the irrigation water

Pomegranate Light Interception

Treatment Key Means

T1 SDI N1 16.59 35.4

T2 DI N1 12.25

T3 SDI N2 14.36 18.8

T4 DI N2 12.1

T5 SDI N3 15.65 35

T6 DI N3 11.59

Means 13.76 29.7

Lysimeter SDI N2 18.53 29* % increase from SDI over DI and from

Lysimeter over SDI-N2 Mean

SDI % Inc.*

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0

100

200

300

400

500

600

700

800

900

1000

4/22 5/17 6/11 7/6 7/31 8/25 9/19 10/14 11/8

Cro

p C

oeff

icie

nt,

Kc

ETo,

ETc a

nd

Pre

cip

., m

m

Date 2011

Evapotranspiration (ETo, ETc), Precipitation and Kc

ETo Precip ETc Kc Poly. (Kc)

Eto=37.7 in

Lys. ETc=21.0 in.

0.13<Kc<0.25

Precipitation=2.7 in.

Pomegranate Water Applied, Precipitation & Eto

0

100

200

300

400

500

600

700

800

900

1000

4/23 5/13 6/2 6/22 7/12 8/1 8/21 9/10 9/30 10/2

0

11/9

Date, 2011

Ref.

Eto

& P

recip

itati

on

, (m

m)

0

100

200

300

400

,W

ate

r A

pp

lied

to

Orc

hard

)mm

(

CIMIS ETo

Rainfall

SDI • Trt 1

DI • Trt 2

SDI • Trt 3

DI • Trt 4

SDI • Trt 5

DI • Trt 6

Eto=37.7 in.

Irrigation=8.49 in.

Rainfall=2.7 in.

Pomegranate Water Balance

NOTE: In 2012 we will measure drainage and change in soil water

content in the lysimeter and calculate the total water balance

Pomegranate Water

Year Eto. Precip. Irrig ETc

2010 49.7 17.3 1.00 2.10

2011 48.1 9.9 8.49 9.422011 values to October 31st only.

Lysimeter ETc adjusted for orchard spacing

Surface Drip Subsurface Drip

WEEDS

Plans for 2012

1. Determine the seasonal N requirement of DI- and SDI-irrigated pomegranate (2 year old trees) that improve NUE without yield reduction.

2. Determine the effectiveness of three N injection rates with DI and SDI on maintaining adequate tissue N in pomegranate.

3. Determine the effect of seasonal N injection rate with DI- and SDI-irrigated pomegranate on leaching rate of NO3-N.

4. Develop fertigation management tools for the growers and present these at seminars and field days.

5. Determine if P, K, Ca, Mg, Zn, Cu, Fe, Mn, B and Se and healthy bioactive compounds are influenced by precise N fertigation with DI and SDI irrigation.

Acknowledgements

CDFA Fertilizer Research and Education Program –

funding

Paramount Farming Co. – trees

Lakos – filter set

Toro – drip tubing

Dorot – valves

BCP – electrical equipment

Verdegaal --Fertilizers

The KARE & ARS support staffs & field crews

SUMMARY & CONCLUSIONS 1. In 2010, the orchard and irrigation system were installed and tested and the trees were irrigated manually by tanking. 2. In early April 2011, the soil was sampled for NO3-N and results showed that NO3-N was very low down to 4-5 ft. depth.

3. The irrigation system was turned on semi-automatic and ETc from the lysimeter was used to irrigate and fertigate the orchard

uniformly. 4. Plant tissue samples indicated a rapid response to AN-20 fertigation. N, P, & K were injected at low concentrations for total amounts of 58,

26 and 53 lb/ac., respectively. 5. From 4/22 to 10/31, CIMIS ETo, precipitation, irrigation and ETc were 48.1, 9.9, 8.5 and 9.4 in. respectively. The Crop coefficient

(Kc) ranged from 0.13 to 0.25. 6. In September, the mean light interception of SDI irrigated trees was 29.7% larger than that of DI irrigated trees.