Evaluation of Wireless Soil Evaluation of Wireless Soil Moisture Measurement Systems Moisture Measurement Systems

with regards to water quantity with regards to water quantity and qualityand quality

Sanjay ShuklaSanjay ShuklaChambal PandeyChambal Pandey

Department of Agricultural and Biological Department of Agricultural and Biological EngineeringEngineering

IntroductionIntroduction Florida ranks 2Florida ranks 2ndnd in vegetable production in vegetable production in USin US

Seepage irrigation is common - upflux Seepage irrigation is common - upflux from the shallow water table (~45 cmfrom the shallow water table (~45 cm))

Visual observation and/or hand-feel Visual observation and/or hand-feel methods result in under/over irrigationmethods result in under/over irrigation

Conventional practice-high water tableConventional practice-high water table• Wastage of water, more runoff, and less Wastage of water, more runoff, and less rainfall storagerainfall storage

• Nutrient leaching to groundwaterNutrient leaching to groundwater SolutionsSolutions

Soil moisture based water table managementSoil moisture based water table management

ObjectivesObjectives

Collect background soil Collect background soil moisture data at a vegetable moisture data at a vegetable farm in South Florida.farm in South Florida.

Evaluate the effects of Evaluate the effects of wireless soil moisture based wireless soil moisture based water table management practice water table management practice on water use, water quantity on water use, water quantity and crop yieldand crop yield

Experimental DetailsExperimental Details Study area = 6.5 haStudy area = 6.5 ha Eight fields (each: Eight fields (each: 274 m x 31 m )274 m x 31 m )

Subsurface Subsurface irrigation and irrigation and drainage system drainage system (SID)(SID)

Study periods:Study periods:• Sep, 02 - May 03 Sep, 02 - May 03 • Sep, 03 - Apr 04Sep, 03 - Apr 04

Soil: Myakka sandSoil: Myakka sand Eggplant and PepperEggplant and Pepper

Data CollectionData Collection

HydrologicHydrologic• Soil moistureSoil moisture

• Wireless Capacitance probeWireless Capacitance probe• Data transmission from field to grower’s Data transmission from field to grower’s officeoffice

• Water tableWater table• RainfallRainfall• IrrigationIrrigation

NutrientsNutrients• GroundwaterGroundwater• SoilSoil

Monitoring DesignMonitoring Design

Background and Test PeriodBackground and Test PeriodSoil Soil Moisture and Water TableMoisture and Water Table

0

10

20

30

40

50

60

70

80

09/2

4/02

10/0

8/02

10/2

2/02

11/0

5/02

11/1

9/02

12/0

3/02

12/1

7/02

01/0

1/03

01/1

5/03

01/2

9/03

02/1

2/03

02/2

6/03

03/1

2/03

03/2

6/03

04/0

9/03

04/2

3/03

Date

% S

oil M

oist

ure

(VW

C)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Wat

er T

able

Dep

th (

m)

SM @ 10 cm (Improved) SM @ 10 cm (Conventional)

Water Table Depth (Improved) Water Table Depth (Conventional)

Potential runoff

Field capacity

Permanent wilting point

Test periodBackground period

Evaluation PeriodEvaluation PeriodSoil Soil Moisture and Water TableMoisture and Water Table

0

10

20

30

40

50

60

70

80

09/1

0/03

09/2

3/03

10/0

5/03

10/1

8/03

10/3

0/03

11/1

2/03

11/2

4/03

12/0

7/03

12/1

9/03

01/0

1/04

01/1

3/04

01/2

6/04

02/0

7/04

02/2

0/04

03/0

3/04

03/1

6/04

03/2

8/04

04/1

0/04

04/2

2/04

Date

% S

oil M

oist

ure

(VW

C)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Wat

er T

able

Dep

th (

m)

SM @ 10 cm (Improved) SM @ 10 cm (Conventional)

Water table depth (Improved) Water table depth (Conventional)

Potential runoff

Field capacity

Permanent wilting point

Total water useTotal water use

101

157

0

20

40

60

80

100

120

140

160

180

Improved Conventional

Tot

al W

ater

Use

(M

illi

on L

)

36% 36% saving saving of total of total water water useuse

Groundwater PGroundwater P

0

0.2

0.4

0.6

0.8

1

1.2

Field 2 Field 4 Field 7

Tot

al P

Con

cent

rati

ons

(mg/

L)

Improved Conventional

p-value = 0.00

p-value = 0.00

p-value = 0.28

Groundwater NOGroundwater NO33

0

10

20

30

40

50

60

70

80

Field 2 Field 4 Field 7

Gro

undw

ater

NO

x-N

con

cent

rati

ons

(mg/

L)

Improved Conventional

p-value = 0.38

p-value = 0.37 p-value = 0.21

Fruit WeightFruit Weight

0

200

400

600

800

1000

1200

1400

1600

1 2 3 4 5 6 8

Field

Ave

rage

fru

it w

eigh

t (g/

plan

t)

Improved Conventional

p-value = 0.06

p-value = 0.47

p-value = 0.18

p-value = 0.65

p-value = 0.03

p-value = 0.19

p-value = 0.18

Waterborne disease-Waterborne disease-PhytophthoraPhytophthora

SummarySummary

Soil moisture based water table Soil moisture based water table management management saved 36% of water.saved 36% of water. 50% less runoff50% less runoff reduced nitrate leaching to the reduced nitrate leaching to the groundwatergroundwater

better crop performancebetter crop performance overall better or equal yieldoverall better or equal yield 100% more yield compared to the 100% more yield compared to the conventional side due to crop diseaseconventional side due to crop disease

ConclusionsConclusions

1.1. Considerable reduction in irrigation Considerable reduction in irrigation water use by soil moisture based water use by soil moisture based water table management compared to water table management compared to the conventional irrigation the conventional irrigation management.management.

2.2. Soil moisture based water table Soil moisture based water table management increased available soil management increased available soil water storage resulting in less water storage resulting in less frequent drainage and runoff eventsfrequent drainage and runoff events

3.3. Soil moisture based water table Soil moisture based water table management reduced nutrient leachingmanagement reduced nutrient leaching