Wireless Auto Water
The researchers who developed it call their innovative breakthrough the Scheduling Supervisory Control and Data Acquisition, or ISSCADA. It could well be termed Automatic Irrigation, as the system allows “applying the right amount of water at the right time and in the right location in a field,” explains Susan O’Shaughnessy, an agricultural engineer at the ARS Soil and Water Management Research Unit in Bushland, Texas.
O’Shaughnessy was part of a team of engineers who created the wireless sensor-based decision-support system that could help automate application rates to specific areas of a crop field on-the-fly using real-time data on pivots equipped with variable-rate irrigation (VRI) technology.
Pinpoint watering rates to plant needs
Considerable variability can exist not only in the field’s terrain and soil composition but also in the individual plants’ water needs, points out Paul Colaizzi, who was also part of the ARS development team. Applying too much water can encourage leaching of nutrients below the root zone, putting them beyond the plants’ reach and closer to underground stores of water. Above ground, surplus water creates conditions for weeds and pests to thrive. Overwatered plants are prone to lodging (falling over) and are more vulnerable to rot and other diseases.
“Variable-rate irrigation can make it easier to spread water, without undue risk of underwatering, or to concentrate water with less risk of overwatering,” O’Shaughnessy says.
Although VRI technology is commercially available, there are still costs, learning curves, and other issues associated with adopting it, the researchers note.
“These barriers include the need for high-speed rural internet and cellular service, advanced soil-plant-atmosphere models, appropriate decision-support systems, sufficiently powerful handheld computers, and wireless sensors that can survive harsh field conditions,” O’Shaughnessy says. “These have been perhaps the most intractable technical barriers so far.”
How they made auto water work
The ARS team’s automated system is the culmination of a multifaceted effort to overcome those hurdles. The team’s efforts include not only developing new, wireless soil-water sensors and plant-canopy thermometers but also mathematical algorithms. Using data acquired from the sensors, the algorithms create daily crop-stress indices and threshold levels that can be integrated with color-coded, geographic information system (GIS) maps. The GIS maps show where, when, and how much you should irrigate or if you should withhold irrigation.
In field trials with corn, cotton, sorghum, and soybeans, ISSCADA-controlled pivots performed as well as pivots that had been manually programed by the team. Tests of ISSCADA under different conditions are also under way at other ARS research sites in Missouri, Mississippi, and South Carolina.
The researchers are collaborating with three companies (Valmont, Dynamax, and Acclima) to refine the irrigation-scheduling system they’ve developed and to integrate it with existing VRI systems. Under a cooperative research and development agreement, “we are developing a software package that integrates the sensor network systems with VRI hardware so that farmers can easily use the system for precision irrigation,” O’Shaughnessy explains. A grant from the USDA National Institute of Food and Agriculture also funds this work.
Colaizzi expects this capability to become important, given the increasing off-farm competition for water for residential, recreational, municipal, and other uses.
With the right tools on hand, you can make the best decisions possible.
“As long as you’re growing crops and have to eat, water will be one of the main variables to be managed – whether it’s more crop per drop or less drop per crop,” Colaizzi say.
By Jan Suszkiw and Dave Mowitz, Executive Editor