Precision agriculture: There’s a drone for that.

In the quest to maximize the efficiency of agriculture for a growing planet, farmers have recently turned to drones. They are using them to detect pests and to map weeds. More recently, researchers have demonstrated that they can aid farmers in making smarter, more efficient use of irrigation water. This helps farmers not only increase yield, but also conserve a valuable resource in high demand.

Researchers’ early forays into employing drones for this end involved mounting them with thermal cameras to take measurements of canopy-air temperature above the crops. Canopy-air temperature is the basis of a widely used index for water stress in plants. The problem with this system is that thermal cameras are expensive, putting them out of reach of many farmers.

A group of Spanish researchers recently found a cheaper approach. In a study published in the journal Precision Agriculture, they showed that a drone mounted with an infrared thermometer does just as good a job—even better, in some regards—at measuring water stress in crops as thermal cameras. But the infrared system can do it as a fraction of the cost.

For the study, the researchers mounted a small infrared thermometer, along with a processor to collect data, on a rotary-wing drone. They conducted a series of flights over sugar beet crops in southwestern Spain to collect the canopy air temperature. They flew the drones at five different altitudes and over two different fields: a normally irrigated one, and one where irrigation had been partially withheld.

The researchers compared these temperature readings with ones from a thermal camera mounted on a drone, which has been the subject of previous research.

Prior to the field tests they ran laboratory experiments to validate the use of the infrared system to accurately measure temperature, and to validate the use of canopy temperature as an indicator of water stress in beets.

In the lab, the researchers found the infrared system accurately measured temperature. They also found that canopy-air temperature was a faithful indicator of the amount of water the beets received. (Water-stressed plants have higher canopy-air temperatures).

In the field, they found that the infrared system did just as good a job as the thermal system in capturing differences in temperature between the normal plots and the drought-induced plots. The main advantage, researchers say, is that the infrared system costs a whopping  3 to 5 percent of the what the thermal camera costs. Another advantage is that unlike the thermal camera system, the infrared technology’s readings were not affected by changes in flight altitude. However, it remains to be seen if this system would work over fields with less dense coverage—such as fruit orchards—the researchers say.

According to researchers, this system is so affordable that even small and medium size farmers could use it and make better use of their water. —Catherine Elton | 2 September 2016

Source: Martinez J, et al. A cost-effective canopy temperature measurement system for precision agriculture: a case study on sugar beet. Precision Agriculture. 2016.

Image: ©Mauricio Lima/Flickr

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