A Generic Soil Test Extractant for Environmental Phosphorus Risk Assessment

By Eric Hamilton

The soil is a vital foundation for most plant life. Our crops rely on this rich trove of nutrients and microbes to help turn sunlight into food. But we've learned over the last few decades that there can be too much of a good thing.

While synthetic fertilizers have greatly increased the yield of crops, they have downsides too. When plants can't absorb all of the nutrients from fertilizers, rain can wash them away. Spilling into streams, lakes and oceans, too much nitrogen or phosphorus leads to dead zones. Dead zones are areas of low oxygen that come as a result of rotting algae. That algae growth was boosted by a big gulp of fresh nutrients once meant for our crops.

If farmers know how many nutrients are in their soil, they can plan to add only what they need. The information can also tell them if their fields are at risk of losing nutrients to the water. That's what soil tests are for. But just like how there is no unified power cord for all our tech devices, there are many different soil tests out there.

"The planet we live on has diverse groups of soils with different chemical and mineralogical properties," says Rishi Prasad, a scientist at Auburn University's Crop, Soil and Environmental Sciences Department. "Region-specific soil tests were developed in the past to meet the regional needs for agronomic fertilizer recommendation.".

This research was recently published in Agrosystems, Geosciences and Environment Journal, a publication of the American Society of Agronomy and Crop Science Society of America.

Prasad's team recently tested if one "universal" soil test could perform better than these region-specific ones. One effective test would make it much easier to compare results between different areas. "It is easier to compare 'apples to apples' than 'apples to oranges,'" says Prasad.