Using its SMAP satellite — Soil Moisture Active Passive — NASA can monitor the amount of water in soils anywhere on Earth. On this map, dated May 16-May 18, drier-than-normal soils are in brown, while wetter-than-normal soils are in blue-greens. / Courtesy NASA

Editor’s note: The following information is excerpted from a June 4, 2018, NASA news report, “NASA Soil Moisture Data Advance Global Crop Forecasts” (

Data from the first National Aeronautics and Space Administration (NASA) satellite mission dedicated to measuring the water content of soils is now being used by the U.S. Department of Agriculture (USDA) to monitor global croplands and make commodity forecasts.

The Soil Moisture Active Passive mission, or SMAP, was launched in 2015. It has helped map the amount of water in soils worldwide. Now, SMAP soil-moisture data are being incorporated into the Crop Explorer website of the USDA’s Foreign Agricultural Service, which reports on regional droughts, floods and crop forecasts. Crop Explorer is a clearinghouse for global agricultural growing conditions, such as soil moisture, temperature, precipitation and vegetation health.

“There’s a lot of need for understanding, monitoring and forecasting crops globally,” said John Bolten, a research scientist at NASA’s Goddard Space Flight Center in Maryland. “SMAP is NASA’s first satellite mission devoted to soil moisture, and this is a very straightforward approach to applying that data.”

Variations in global agricultural productivity have tremendous economic, social and humanitarian consequences. Among the users of these new SMAP data are USDA regional crop analysts who need accurate soil-moisture information to better monitor and predict these variations.

“The USDA does crop-forecasting activities … and one of the main pieces of information is the amount of water in the soil,” said Iliana Mladenova, another research scientist at Goddard.

These soil-moisture conditions, along with tools to analyze the data, are also available on Google Earth Engine. There, researchers, nonprofit organizations, resource managers and others can access recent data as well as archived information.

“If you have better soil-moisture data and information on anomalies, you’ll be able to predict, for example, the occurrence and development of drought,” Mladenova noted.

The timing of the information matters as well, she added — if there’s a short dry period early in the season, it might not have an impact on the total crop yield, but if there’s a prolonged dry spell when the grain should be forming, the crop is less likely to recover.

With global coverage every three days, SMAP can provide the Crop Explorer tool with timely updates of soil-moisture conditions that are essential for assessments and forecasts of global crop productivity.

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