Soil Moisture Monitoring Using Wireless Sensor Network

Ruixiu Sui

USDA-ARS Crop Production Systems Research Unit

Stoneville, Mississippi

18th World Congress of CIGR Beijing, China

September 16-19, 2014

Non-Irrigated

Irrigated

• Mid-South of USA• Major crop production Area• Annual Precipitation: 130cm• Hot and Less rainfall in summer• Supplemental irrigation needed

INTRODUCTION

Irrigated

INTRODUCTION

• Uncertainty in the amount and timing of rainfall is a serious risk to producers in the Mid-South

• Producers have become increasingly reliant on irrigation, but very few use any irrigation scheduling aids

• Timely and accurate determination of soil water status and weather conditions are essential to irrigation scheduling

INTRODUCTION

Mid-SouthRegion

INTRODUCTION

• Irrigation scheduling methods–Weather-based -- schedule irrigation based on

the amount of water lost by plant ET and the amount of effective rainfall and irrigation water entering into the plant root zone.

– Soil moisture-based -- measure soil moisture levels in the plant root zone and apply water if there is water shortage for plants

– Plant-based -- directly detect plant responses to water stress and initialize irrigation as plants indicate suffering from water stress.

INTRODUCTION

• Soil moisture measurement required for soil-moisture-based irrigation scheduling

• Sensor technologies available for measuring soil moisture -- neutron probes, electromagnetic (EM) sensors (capacitance, TDR, resistance,..)

• Wireless sensor networks offer capability of providing continuous, real-time, in-situ measurements under a variety of operating conditions

OBJECTIVES

• The goal of this research is to develop improved irrigation application and scheduling techniques for humid regions

• Specific objective is to develop wireless sensor network (WSN) for monitoring soil water status and collecting weather data for irrigation applications

6”

12”

24”

Point AreaData Logger &

Wireless modemAccess

Data online

Wireless Sensor Network

Wireless Data Logger Frequency: 900 MHz Input: 5 Channels Storage: 1M Power: 5 AA Bat.

Em50GEm50R EC-5 5TM

Wireless Sensor Network

Data Station receives and stores data from Em50R loggers; Em50G cellular data logger; Modem transmits data online via cellular network

Data Station Wireless ModemData logger

• Rain gauge sensor

• Radiation sensor

• Temperature sensor

• Humidity sensor

• Wind speed & direction sensors

• Data logger

• Solar panel for power supply

• 10-ft Tower

• Software package

Weather Sensors

• Installed sensors and loggers in multiple locations in cotton, corn, soybean fields

• 3-4 sensors each location in 15, 30, 46 cm depths

• Sensor models: EC-5, 5TM, MPS-2

• Soil moisture measured 24/7 at one hour interval

Sensor Installation

Sensor Installation

2. Put in bracket

Data Station

• Dig a hole• Insert the sensors

Horizontally• 3 MC sensors/hole

• Soil sampler• Gas-powered

auger

Required to lay down the logger pole for applying Chemicals

Issue for Field Operation

Antenna Mounts Developed

Click on picture to play video

Antenna Mounts Test

Data Logger Installation

2. Put in bracket

Data Station

EM50R Logger

EM50G Logger

WSN in Soybean Field

Cotton Field (Logger 18-50G)

Corn Field (Logger19-50G)

Soybean Field (Logger 20-50G)

Date RSSI Attempts RSSI Attempts RSSI Attempts14-May-12 19 1 14 1 NA NA21-May-12 19 1 10 1 NA NA28-May-12 19 1 11 1 NA NA4-Jun-12 20 1 9 1 NA NA11-Jun-12 19 2 9 1 NA NA18-Jun-12 18 1 9 1 10 125-Jun-12 17 1 9 2 13 12-Jul-12 14 1 10 1 12 19-Jul-12 10 1 10 1 10 116-Jul-12 11 1 8 1 11 123-Jul-12 13 1 8 1 10 130-Jul-12 10 1 9 1 13 16-Aug-12 10 1 11 1 13 113-Aug-12 15 1 9 1 12 120-Aug-12 16 1 NA NA 12 127-Aug-12 16 1 NA NA 16 13-Sep-12 17 1 NA NA 20 110-Sep-12 17 1 NA NA NA NA

Received Signal Strength Indication (RSSI)

Logger Location

Crop5/1/13 – 5/15/13

5/16/13 - 5/31/13

6/1/13 - 6/15/13

6/15/13 - 6/30/13

7/1/13 - 7/11/13

1 Cotton NA* 8 12 11 20

2 Cotton NA 17 19 19 18

3 Cotton NA 19 20 20 19

4 Cotton NA 19 18 20 20

5 Cotton NA 20 19 19 17

6 Cotton NA 19 16 17 15

7 Corn 77 72 57 55 52

8 Corn 71 64 40 54 55

9 Corn 70 62 33 25 18

10 Corn 66 59 25 29 30

11 Corn 62 43 29 12 12

12 Soybean NA* 70 77 77 76

13 Soybean NA* 62 63 61 70

14 Soybean NA* 67 67 64 60

15 Soybean NA* 63 64 62 59

16 Soybean NA* 60 60 56 50

RSSI in 2013

Downloading Data Online

Soil Moisture Data From WSN

Soil Moisture Data From WSN

• WSN collected data for 3 years• Data have been used for

irrigation scheduling• Performed well in general• Thunderstorms could interrupt

data transmission• Animals (wild dog, pig, turtles)

might chew cables

Variable Rate Irrigation in Soybeans Corn Research Field

Irrigation Research in Cotton

SUMMARY

• Wireless sensor network was built and deployed for monitoring soil moisture and collecting weather data for 3 years. The WSN is capable of automatically measuring and wirelessly transferring soil moisture and weather data online, enabling remote access of the data;

• An antenna mount was developed for field use with wireless data loggers;

• Evaluated for 3 years; The WSN performed well;

• Soil moisture data and weather data collected by the WSN has been used for irrigation research.

Acknowledgements This project was partially supported by

Cotton Inc.Thank Mr. Jonnie Baggard for his assistance in this project.

Disclaimer Mention of a commercial product is solely for the

purpose of providing specific information and should not be construed as a product endorsement by the authors or the institutions with which the authors are affiliated.

Ruixiu Sui, Ph.D.Research Agricultural Engineer, Lead ScientistUnited States Department of Agriculture (USDA)Agricultural Research Service (ARS) Crop Production Systems Research Unit141 Experiment Station RoadStoneville, MS 38776Email: ruixiu.sui@ars.usda.govhttp://www.ars.usda.gov/msa/jwdsrc/cpsru/sui