New Mexico State University scientists are evaluating a high-tech soil moisture monitoring system that's relatively cheap and can send data from the field to a farmer's desktop computer in real time via radio waves.

The system, called ECH2O, uses a new sensor for measuring soil water content, said Robert Flynn, an agronomist with NMSU's Agricultural Science Center at Artesia. The goal is to give New Mexico farmers a tool that allows them to irrigate where they need to and to use only the water necessary, he said.

Experimental fields of alfalfa, row crops, and warm and cool season grasses are being used as test plots for the equipment. “Alfalfa and the forage grasses were chosen first because of their importance to New Mexico's livestock industry,” Flynn said. “They're high water users, but they can be drought tolerant once they're established.”

The ECH2O project is funded with a grant from Sandia National Laboratories' Small Business Division and support from NMSU's Agricultural Experiment Station. The project expands this summer to experimental fields of cotton and corn.

While spring thunderstorms packing heavy rain and strong winds have rolled through the state, experts agree the dry spell isn't over. The relentless drought still means that New Mexico farmers must brace for dramatic reductions in water supplies this summer.

It also calls for using water wisely now and in the future, said Flynn, who serves as acting superintendent of the 75-acre science center six miles south of Artesia.

The ECH2O sensors — made by Decagon Devices of Pullman, Wash. — were selected for their ability to maintain good physical contact with the soil and maintain readouts at very low soil moisture, Flynn said. Prices for soil moisture monitors range from $20 for garden tensiometers to thousands of dollars for advanced technology units.

The NMSU project began last summer with software and sensor installations. ECH2O sensors were placed in one foot increments to a depth of five feet, and then linked to an above-ground data logger. The configuration is used to determine the most effective depth for farmers to eventually place the sensor.

One advantage of this system is that the data can be remotely downloaded by radio signal to computer workstations off site or in the field through a hand-held computer that is inserted directly into a data logger, Flynn said.

Calibrate to area

To get accurate readings Flynn spent last summer calibrating preset factory settings to Artesia's growing conditions and soil types. He found that the sensors were effectively measuring soil moisture to total dryness, well past the plant's wilting point. To accomplish that task, the tongue-depressor shaped sensors send an electrical signal to a computer program, which translates that data into soil water content.

Next step for Flynn is to finish field installations, collect data over the summer, and then begin correlating moisture readings with plant performance and weather conditions.

“If we can model and monitor a system at the science center, then we can look at applying this information to larger systems such as the Carlsbad Irrigation District,” Flynn said. “This type of information could be used for water delivery based on verifiable demand for water when it's needed most, as well as to prevent overirrigation.”