News & Insights

Public Comment on Initiatives to Protect and Improve Water Quality

The Natural Resources Conservation Service (NRCS) recently requested public input for use in refining the Mississippi River Basin Healthy Watershed Initiative and the National Water Quality Initiative. These initiatives are designed to address pollution issues that affect water quality in the Mississippi River. Because one source of nutrient pollution is the leaching of nitrogen and phosphorus from agricultural soils, and because we have the means to address conditions that lead to that leaching, Trace Genomics issued a public comment. The full text is below and may also be accessed here.

Agricultural soils are a major contributor to nutrient pollution due to the leaching of nitrogen and phosphorus from overapplication of fertilizers on many fields. This source of pollution is one of the easiest to resolve, since it is not necessary to build additional infrastructure like what is required to remove nutrients from wastewater. Reducing the nutrient runoff from agricultural sources can be as simple as reducing fertilizer application where soils are already saturated with phosphorus and nitrogen.

To better protect and improve water quality, the NRCS should consider the value of measuring nutrient levels in agricultural soils directly. A map of the soil phosphorus saturation over a wide geographic area can provide an informed picture of where nutrient runoff is most likely to originate. Understanding the level and mobility of soil nitrogen and phosphorus also has collateral cost-saving and environmental benefits for farmers and landowners. Soil tests are cost-effective and scalable, and growers can use this information to be more strategic about fertilizer type and placement.

In order to have the best understanding of phosphorus availability in agricultural soils, the NRCS should take into account all components of the soil, including the soil microbiome. Phosphorus mineralizing and solubilizing microbes can impact the phosphorus saturation level and should be considered when measuring phosphorus availability. The best technology available to do this is shotgun metagenomics (sequencing all DNA in a soil sample) to measure these genes directly, rather than using fingerprint DNA sequences to make assumptions about microbial community functions.

The Maryland Department of Agriculture has set a precedent for using soil phosphorus tests to protect vulnerable watersheds. In the Chesapeake Bay watershed, soil tests are used to identify areas where soil is fully saturated with phosphorus. In saturated areas, fertilizer application is restricted and management techniques to remove excess phosphorus, such as crop rotations, are encouraged. Their strategy has been effective at reducing phosphorus runoff into the Chesapeake Bay and has contributed to improved water quality.

You may browse all posted comments issued in response to this request here.