About 60 percent of California is experiencing “exceptional drought,” the U.S. Drought Monitor’s most dire classification. Without enough water in the soil, seeds can’t sprout roots, leaves can’t perform photosynthesis, and agriculture can’t be sustained.
Currently, there is no global network monitoring soil moisture at a local level. Farmers, scientists and resource managers can place sensors in the ground, but these only provide spot measurements and are rare across some critical agricultural areas in Africa, Asia and Latin America. The European Space Agency’s Soil Moisture and Ocean Salinity mission measures soil moisture at a resolution of 50 kilometers, but because soil moisture can vary on a much smaller scale, its data are most useful in broad forecasts.
Enter NASA’s Soil Moisture Active Passive (SMAP) satellite. The mission, scheduled to launch this winter, will collect the kind of local data agricultural and water managers worldwide need.
SMAP monitors the top 5 centimeters of soil on Earth’s surface. It creates soil moisture estimates with a resolution of about 9 kilometers, mapping the entire globe every two or three days. Although this resolution cannot show how soil moisture might vary within a single field, it will give the most detailed maps yet made.
“If farmers of rain-fed crops know soil moisture, they can schedule their planting to maximize crop yield,” said Narendra Das, a water and carbon cycle scientist on SMAP’s science team at NASA’s Jet Propulsion Laboratory in Pasadena, California. “SMAP can assist in predicting how dramatic drought will be, and then its data can help farmers plan their recovery from drought.”