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Tending the fields from afar.

Here's a pipe dream for you: At the push of a button, faraway fields report in on the status of their soil, water, and crops. Instantly, farmers are able to take action against insect pests, weather changes, or deteriorating soil conditions.

Currently, the concept of long-distance monitoring--scientists call it "remote sensing"--promises more than it can effectively deliver, in part because of the heavy investment required for the high technology equipment. And often the result is a mountain of data needing interpretation before it can be used in making day-to-day farming decisions.

But now ARS scientists have some down-to-earth, remote-sensing solutions to a number of these problems. In this issue, an article describes how tractor-mounted computers may use Global Positioning System (GPS) satellites to help farmers save fertilizer, cut water pollution risks, or measure encroaching salinity in crop fields.

Some remote-sensing systems do not require orbiting satellites. In February 1991, Agricultural Research told of airplanes equipped with special video cameras that bring back to research labs a videotaped bird's-eye view of the relative health of crops still growing in the fields. The same system is also used to provide information on the effectiveness of various irrigation management systems.

One camera uses a near-infrared filter, one uses a red filter, and the third is equipped with a yellow-green filter. The three images feed into three Super-VHS recorders, and a fourth recorder captures the color-infrared composite.

The scientists can tell whether the crops they're seeing on tape are healthy or plagued by pests, environmental stress, or disease--information that farmers can use in limiting the damage.

An important side benefit for farmers: Such aerial videos could speed up the process of settling crop insurance claims after a disaster. As an alternative to waiting for an adjustor to finish trudging the fields, video offers a quick photographic document of the location and size of damaged areas.

Other potential benefits of an "eye in the sky" include early information on:

* Range regrowth, a prime consideration in calculating stocking rates for livestock.

* Damage from herbicides drifting from nearby crops.

* Changes in the vegetative lineup on the range due to weather or grazing patterns.

* Nutrient deficiencies in crop and range plants.

Such monitoring can help reveal what happens to rain once it's fallen: How much moves downward through the soil, how much drains away, how much is taken up by thirsty plants.

Another very interested audience includes those whose livelihood depends on the latest news on the status of the nation's ranges, pastures, and croplands.

Someday, scientists say, farmers and ranchers may be able to pop a tape into their home VCR to check on the health of their crops, whether the potential problem is an encroaching insect, an invasion of weeds, or simply lack of rain.

Remote sensing's benefits aren't limited to farmers. The same three-camera system developed by the ARS researchers to monitor crop health might someday go into space with NASA craft. There it might be used for purposes like checkups of marine environments such as Texas' South Padre Island, where oyster beds are threatened by urban pollution.

Turning to another area of concern, when scientists wanted a closer look at what happens to heavy rains hitting the range at Walnut Gulch near Tombstone, Arizona, in the summer of 1990, they tackled the problem with equipment ranging from rain gauges to airplanes and satellites. [See Agricultural Research, November 1990]

While researchers on the ground measured rainfall, runoff, water movement into and through the soil, soil moisture levels, evaporation, water uptake by plants and other factors, remote-sensing equipment on the airplanes and satellites spewed out similar data from on high.

One early finding from the Arizona effort: Soil moisture levels after heavy rains tend to be more uniform over larger areas than was previously thought. Researchers say this sort of information could have an impact on the use of remote sensing in flood prediction.

Improvements in drought prediction could also be a possibility. It appears that "sensible" heat from the land--the kind of heat you can feel--as well as "latent" heat, energy stored in the form of evaporating water, play a major role in determining when and where rain will fall.

If this proves true, reliable remote-sensing data on the water and energy balances of semiarid rangelands could play a role in anticipating changes in climate on a regional or even a global scale, scientists say. In turn, scientists must learn how to monitor more accurately the hydrologic cycle of the rangelands.

Fine-tuning applications of crop inputs such as fertilizer means less is wasted--a savings to the farmer. And tightening the margin between what's applied and what's needed by the crop is also good news for the environment, since the likelihood of problems such as surplus fertilizer leaching into groundwater supplies is lessened.

The heyday of technological advances for U.S. agriculture is far from finished. Someday farmers may count among their most valuable "farm tools" a satellite they've never seen, but that faithfully beams down the information they need to play their part in feeding the world.
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Title Annotation:Forum; how tractor-mounted computers may use satellites to help farmers to check on the health of their crops
Author:Hays, Sandy Miller
Publication:Agricultural Research
Article Type:Column
Date:Feb 1, 1992
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