Nutrient Management Strategies for Vegetable

Production in Desert Soils

Charles A. Sanchez

Professor and Director

Yuma Agricultural Center

I. Efficient N Managementfor Desert Vegetables

0

20

40

60

80

100

120

140

0 50 100 150

DAP

N Up

take

(kg/

ha)

Sept. 16

Nov. 1

0

40

80

120

160

0 200 400 600 800 1000

EDD

N U

ptak

e (k

g/ha

)

Sept. 16

Nov. 1

Timed N Availability

Sidedress ApplicationControlled Release FertilizersFertigation

Response of Lettuce to N Management (97-98)

0

5

10

15

20

Control SD-Urea

Urea Agr#1 Agr#2 Dur Meis#1 Meis#2

N Management

Yie

ld (M

g/ha

)

Broadcast

Band

Response of Broccoli to N Management (97-98)

0

1

2

3

4

5

6

7

8

Control SD-Urea Urea Agr#1 Agr#2 Dur Meis#1 Meis#2

N Management

Yie

ld (M

g/ha

)

Broadcast

Band

Summary of Responses to N Management

Response Crop Frequency Soil Texture

CRN=PP>SD Lettuce 2 Clay

SD=CRN=PP Lettuce 4 Clay and Clay loam

WR=CRN=PP Cauliflower 3 Clay and Clay loam

Broccoli 3 Clay and Clay loam

SD=CRN>PP Lettuce 1 Clay loam

Broccoli 2 Loamy Sand

CRN>SD>PP Lettuce 1 Clay Loam

Lettuce 4 Sand

Cauliflower 1 Sand

CRN>SD Lettuce 1 Sand

Cauliflower 1 Sand

Number of N Applications for Varying Soil Types

Soil Texture Recommended Number of N Applications per Crop

clay, sandy clay, silty clay

1 - 2

clay loam, silty clay loam, silt, silt loam, sandy clay loam

2-4

sandy loam, loamy sand

3-5

sand

8-15

0

20

40

60

80

100

120

0 200 400 600

N Rate (kg/ha)

Yie

ld (

Mg

/ha)

MU

MUAS

Fertigation

0

5

10

15

20

25

30

35

40

0 100 200 300 400 500

N Rate (Kg/ha)

Yiel

d (M

g/ha

)

FERTIGATION

CRN

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

0 500 1000 1500 2000 2500 3000

Heat Units

Prop

ortio

n of

N re

leas

ed

Polyon

Summary

When conditions for N losses were high SD and CRN management strategies were superior.

Under extremely warm conditions some CRN technologies have the potential to cause stand reduction.

Under some production scenarios, the use of CRN strategies were economically favorable.

Plant and Soil Testing

0

20

40

60

80

100

120

0 5000 10000 15000 20000 25000

Midrib nitrate-N (ppm)

Rel

ativ

e Y

ield

(%

)

Desirable Levels of Midrib Nitrate-N for Lettuce

Dry Midrib Test 8,000 to 10,000 mg/kg

Sap Test 480 to 542 mg/L

Desirable Levels of Petiole Nitrate-N for Cauliflower

Growth Stage Critical LevelsDry Tissue

(mg/kg)Sap Test(mg/L)

4 to 6 leaf 11,000 74010-12 leaf 9,000 640First buds 7,000 550Head Development 2,500 500Pre-harvest 1,500 290

N<CLYield Response

N>CLNo Yield Response

Predicted Response

A positive responseis predicted but noresponse occurs (E1)

No is response ispredicted and no response occurs (C)

A positive responseis predicted and one occurs (C)

No response is predicted but apositive response occurs (E2)

Obs

erve

d R

espo

nse

Yie

ld r

espo

nse

No

yiel

d re

spon

se

Summary of Diagnostic Accuracy Evaluation Summary of Diagnostic Accuracy Evaluation for Tissue Testsfor Tissue Tests

Crop Diagnostic Accuracy

Dry Midrib NO3-N

Sap NO3-N

Lettuce C 48% 47% n=54 E1 33% 24% E2 19% 29% Broccoli C 47% 39% n=51 E1 16% 12% E2 37% 49% Cauliflower C 50% 71% n=38 E1 29% 3% E2 21% 26%

Response of Lettuce to Sidedress N

Nitrate-N(ppm)

PredictedResponse

ActualResponse

DiagnosticAccuracy

Midrib 11,350 - + + E2Sap 811 - + + E2Soil 5 + + + C

Quick Soil 2 + + + C

Summary of Diagnostic Accuracy Summary of Diagnostic Accuracy Evaluation for Soil TestsEvaluation for Soil Tests

Crop Diagnostic Accuracy

Soil Test NO3-N

Quick Test NO3-N

Lettuce C 55% 64% n=33 E1 36% 27% E2 9% 9% Broccoli C 73% 75% n=36 E1 23% 28% E2 4% 0% Cauliflower C 52% 45% n=31 E1 32% 32% E2 16% 23%

SummarySummary

While sap or midrib nitrateWhile sap or midrib nitrate--N tests give an N tests give an indication of the plants N nutritional status indication of the plants N nutritional status they are not sufficiently sensitive or reliable they are not sufficiently sensitive or reliable to serve as the sole basis for making to serve as the sole basis for making sidedress N fertilizer decisions.sidedress N fertilizer decisions.

We suspect that genetic variation, We suspect that genetic variation, inefficient irrigation practices, and perhaps inefficient irrigation practices, and perhaps other unknown factors interact to limit the other unknown factors interact to limit the reliability of midrib or sap tests.reliability of midrib or sap tests.

Summary (continued)Summary (continued)

PrePre--sidedress soil tests were superior to plant sidedress soil tests were superior to plant tests.tests.

However, soil test appear to be occasionally However, soil test appear to be occasionally compromised by inefficient irrigation practices.compromised by inefficient irrigation practices.

Petiole Nitrate-N of Cauliflower to Irrigation

02000

40006000

800010000

1200014000

1600018000

40 60 80 100 120DAP

Mid

rib

NO3-

N (m

g/kg

)

50% ET

100% ET

150% ET

CL

Relevant Questions.Relevant Questions.

When do I irrigate (Irrigation timing)?When do I irrigate (Irrigation timing)?

How much water do I apply (Required depth)?How much water do I apply (Required depth)?

How do I (design and) operate my system?How do I (design and) operate my system?

FlowFlow

Border length and widthBorder length and width

Land slopeLand slope

Cutoff (time or distance)Cutoff (time or distance)

Elements of Efficient IrrigationElements of Efficient Irrigation

Irrigation Scheduling (Timing and Required Irrigation Scheduling (Timing and Required Depth).Depth).

Adjustment of required depth for salt Adjustment of required depth for salt management (Leaching Requirement).management (Leaching Requirement).

Irrigation Design and Management (Efficient Irrigation Design and Management (Efficient and Uniform application of Required Depth).and Uniform application of Required Depth).

0

0.2

0.4

0.6

0.8

1

1.2

0 0.2 0.4 0.6 0.8 1

Depletion of Available Water to 30 cm (%)

Re

lati

ve Y

ield

Design and management

Design and management– physical dimensions [design] – Bed slope [design] – inlet flow rate [design + management]– cutoff time (distance) [design + management]

Zero-Inertia Model

Q

x

A

t

Z

t 0

Y

xs so f

S fQ

nC

2

A Ru

2

2 43

Aggregate comparison of model-predicted and field-observed advance, vegetables.

0

30

60

90

120

0 30 60 90 120

Model-predicted advance (min)

Fie

ld-o

bse

rve

d a

dva

nce

(m

in)

1:1

1 0 1 4 1 8 2 2 2 6 3 0 3 4 3 8 4 2 4 6 5 0

F u r r o w i n l e t f l o w r a t e ( G P M )

5 0

8 4

1 1 9

1 5 3

1 8 7

2 2 1

2 5 5

2 8 9

3 2 4

3 5 8

3 9 2

Cu

toff

tim

e (m

in)

Application efficiency (fine-textured soil)

0

25

50

75

100

0 0.02 0.04 0.06 0.08

Bed slope (%)

Ea,

Er

and

DU

lq (%

)

Er

Ea

DUlq

Performance indices as a function of bed slope, Qo = 0.08 cfs/ft

Application efficiency expressed as a function of furrow length, Zr = 80 mm

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25

50

75

100

0 50 100 150 200 250 300

Furrow length (m)

Ap

pli

ca

tio

n e

ffic

en

cy (

%)

Qo = 50 GPM Qo = 24.8 GPM Qo = 11.9 GPM

Current Research

FertigationSalinity Assessment for Irrigation

ManagementRemote Sensing for Irrigation Management

Soil Br- profile along three transects in an irrigation basin, two days after a fertigation event

0.0

1.0

2.0

3.0

4.0

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6.0

7.0

8.0

9.0

0 40 80 120 160 200

Distance (m)

Br-

am

ou

nt

(g/m

)

Transect 1 Transect 2

Transect 3 Average required application

EM 38-DD

gps control boxComputer platform

gps antenna

Retractable Tube

SALT MAPPER

Thermal detector aerial image collected on Oct. 23, 2001

0 200 400 600 800

Highly Organic

Clay

Clay Loam

Silt Loam

Loam

Sandy Loam

Loamy Sand

Sand

Soil Texture Variation in Lettuce Field

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Distance (ft)

0

200

400

600

Dis

tan c

e (f

t)

Volumetric Soil moisture before irrigation on Oct. 18 2001

0 200 400 600 800 1000 1200

Distance (ft)

0

200

400

600

Dis

tan c

e (f

t)

GPS referenced lettuce yield in Imperial Valley

Summary

N uptake patterns are useful for developing efficient N management strategies

Depending on the production scenario, split sidedress N application, fertigation, and CRN are all viable options for enhancing fertilizer use efficiency

Soil and plant testing can be useful in guiding post plant N applications

Efficient Irrigation is an important prerequisite for efficient N management

II. P Management for Desert Vegetables

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20

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100

0 100 200 300 400

Time (hr)

P so

rbed

(%)

25ppm

1000ppm

Sanchez 1980

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100

200

300

400

500

600

700

800

900

1000

0 10 20 30 40 50 60

Equilibrium P (ppm)

P s

orb

ed (

pp

m)

Sanchez 1982

• The reaction of P with CaCO3 consist of initialsorption reactions followed by precipitationwith increasing concentrations of P (Cole, 1953;Griffin and Jurinak, 1973; Holford andMattingly, 1975).

• Most added P would precipitate initially asdicalcium phosphate dihydrate (DCPD) anddicalcium phosphate (DCP) (Lindsay, 1979).

• These products undergo a slow conversion tosuch compounds as octacalcium phosphate(OCP), tricalcium phosphate, (TCP) or one ofthe apatites (Lindsay and Moreno, 1960).

P reactions in calcareous soils

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1

1.2

1.4

1.6

8 10 12 14 16

Soil Temperature

PS

-P (

pp

m)

for

max

imu

m y

ield

Sorbed P

Organic PSolution PP Minerals

Plant Uptake

Fertilizer P

Immobilization

Mineralization

Precipitation

Dissolution

Desoption

Sorption

Leaching and Runoff

Response of lettuce to Preplant and Sidedress NPK

0

10

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30

40

50

60

70

0 25 50 100

NPK Fertilizer Recommendation (%)

Yie

ld (

Mg

/ha)

No SD

SD 7 DAT

SD 14 DAT

SD 21DAT

SD 28 DAT

05

10152025

303540

4550

0 100 200 300 400

P rate (kg/ha)

Yie

ld (

Mg

/ha

)Band

Broadcast

Sanchez, Swanson, and Porter 1990

Response of Celery to P Rate and Placement

P rate Marketable yield

(kg/ha) (Mg/ha)0 21.650 40.1100 36.7150 40.8200 39.9

L**Q**P placementBroadcast 35.3Band 32.6

NS

Espinoza, Sanchez, and Schueneman, 1993

• The effectiveness of P placementstrategies depends on the crop, thesoil, and crop cultural practices.

SummaryP added to soil is quickly rendered

insoluble.Both physical sorption and precipitation

reactions appear to be involved.At high soil pH values P fixation is

associated with the carbonate fraction.Soil temperature can influence P availability

to crops under some circumstances.

Summary (continued)

Soil and plant tissue tests are viable tools for P management of vegetable crops.

The P fertilizer required should be applied preplant

P placement is often an effective management strategy for improving fertilizer use efficiency.

III. Understanding Why Crops in the Desert Rarely Respond to

K Fertilization

Properties of Selected Soils

Soil Series Total K(g kg-1)

Exchangeable K(mg kg-1)

Clay Mineralogy

Antho 22.0 366 S>MI>K

Gilman 21.1 280 S>MI>K

Glenbar 20.1 257 S>MI=K>Q

Grabe 24.8 549 S>MI>K=CA

Indio 17.3 315 S>MI=K>Q

Pima 26.0 430 S>MI K Q

Casa Grande 29.9 560 S<MI>K<PG

Mohall 27.7 309 S=MI<K

Superstition 31.0 100 S>MI=K=PG>Q

Gadsden 18.1 460 S>MI=K>Q

S-SMECTITE; MI-MICA; K-KAOLINITE; Q-QUARTZ; CA-CALCITE;PG-LYGORSKITE

Calculated Sufficiency and K Desorption

Soil Series SufficiencyLevel K(mg kg-1)

Difference betweenExchangeable and Sufficiency (mg kg-1)

K DesorbedPer 30 min.(mg kg-1)

Antho 143 223 18

Gilman 136 144 17

Glenbar 138 119 15

Grabe 171 378 16

Indio 158 157 12

Pima 169 261 13

Casa Grande 137 423 33

Mohall 141 168 16

Superstition 120 -20 11

Gadsden 173 287 13

Summary of Clay Mineralogy

Clay mineralogy was a mixed composition of smectitie, mica, kalonite, palygorskite, calcite, and quartz.

All soils contained K bearing mica, typically associated with high K release rates.

These soils contained negligiable amounts of vermiculite, known for a high capacity to fix K.

Cumulative Time, hours

K R

ele

as

e, m

g k

g-1

0

2000

4000

6000

8000

10000Pima Casa Grande Mohall Gilman Indio

Cumulative K released to calcium resin by ten representative soils.

0 200 400 600 800

K R

ele

as

e, m

g k

g-1

0

1000

2000

3000

4000

5000

6000Gadsden Glenbar Antho Grabe Superstition

Cumulative Time, hours

K R

ele

as

e, m

g k

g-1

200

400

600

800

1000

1200

1400

1600Pima Casa Grande Mohall Gilman Indio

Cumulative K released to calcium resin by claysof ten representative soils on a whole soil basis.

0 200 400 600 800

K R

ele

as

e, m

g k

g-1

0

200

400

600

800

1000

1200

1400

1600Gadsden Glenbar Antho Grabe Superstition

Nonexchangeable K

Solution PExchangeable K

Plant Uptake

Applied K

Release

Fixation

Leaching and RunoffMineral K

Potassium Applied in Irrigation Water

5071Sweet Corn

5984Onions

2130Lettuce

4260Carrots

5274Melon

5071Broccoli

Irrigation K

(kg ha-1)

Irrigation

Water (cm)

Crop

Irrigation AE=70%

Comparison of K Applied in Irrigation Water and Amount Accumulated by

CropCrop Irrigation K

(kg ha-1)

Crop Accumulation(kg ha-1)

Broccoli 50 238

Melon 52 176

Carrots 42 409

Lettuce 21 192

Onions 59 196

Sweet Corn 50 119

100 200 300 400 500 600

Soil Test K (mg/dm3)

100

200

300

400

500

600

So

il T

est

Na

(mg

/dm

3)

Celery (Harmer and Benne, 1945; Harmer et al. 1953).

Cabbage (Costigan and McBurney, 1983; Costigan and Mead, 1987).

Lettuce (Pereira and Westerman, 1978; Burns, 1986; Burns and Hutsby, 1986; 1987; Costigan and Mead, 1987).

Tomatoes (Figdore et al., 1987;1989).

Other Vegetable Crops Showing Responses to Na when K Limiting

Sodium Applied in Irrigation Water

Crop IrrigationWater (cm)

Irrigation Na(kg ha-1)

Broccoli 55 719

Melon 60 785

Carrots 62 806

Lettuce 27 355

Onions 79 1030

Sweet Corn 60 780

Irrigation =ET/(1-LR)

Summary Many agricultural soils in the southwestern desert

have soil test K levels sufficient for optimal crop production.

Many agricultural soils have a high capacity to replenish K to the soil solution and exchange sites due to their clay content and clay mineralogy.

Irrigation water used in the area has the potential to contribute significant amounts of K (and Na) for crop production.

In addition, Na can partially substitute for K for some important crops produced in the region.