Newswise — April 24, 2015 - In celebration of the International Year of Soil 2015 (IYS), the Soil Science Society of America (SSSA) is coordinating a series of activities throughout to educate the public about the importance of soil. April’s theme is “Soils Clean and Capture Water”. In SSSA’s April 15 Soils Matter blog post, experts explain how scientists are looking to tap a different water source for agriculture: “green water”.

According to Gary Pierzynski, the traditional source of water for agriculture has been from freshwater sources (lakes, river, and streams). Pierzynski is a soil scientist and professor at Kansas State University.

Scientists refer to this freshwater as “blue water”. Green water is the water in soil that is potentially available for plants to take up and used. Green water must pass through the region of soil found close to and influenced by roots.The rhizosphere is the region of soil found close to and influenced by roots. Green water is held in this portion of soil. Photo courtesy of flickr/NRCS Soil Health.

The key to helping plants get this green water is healthy soils. “Healthy soils with plenty of nutrients and soil physical properties favorable for root growth will lead to healthy plant root systems,” says Pierzynski. Those roots will take up more water for transpiration than smaller root systems. The plants will grow larger and create lush canopies that in turn provide shade and decrease evaporation from the soil. More green water is then available for transpiration that will stimulate more crop growth.

Researchers are currently finding ways to capitalize on plant-soil feedbacks and optimize the community of soil microorganisms in the rhizosphere, one of the great frontiers in soil science. That work is a key ingredient in the recipe for better using green water and expanding crop production.

As part of their celebration of IYS, SSSA is developing a series of twelve 2-minute educational videos. April’s Soils Clean and Capture Water video can be viewed at Educational materials can be viewed at by clicking on the April tab.

Follow SSSA on Facebook at, Twitter at SSSA_Soils. SSSA also has a blog, Soils Matter, at Additional soils information is on, for teachers at, and for students through 12th grade,