Researchers evaluating Ohio’s Phosphorus Risk Index to keep nutrients on fields

Ohio researchers are in the midst of evaluating the state's Phosphorus Risk Index through a three-year project that monitors edge-of-field runoff.

Edge-of-field monitoring equipment has been installed on eight fields in the Scioto, eight in the Grand Lake St Mary’s and 14 in the Western Lake Erie Basin watersheds. Data is being collected on surface and subsurface runoff water, soil, site and farmer management practices. In the first year the team has collected and analyzed more than 4,000 water samples.

Ohio State University researcher Libby Dayton is using the results from the project to evaluate/revise the U.S. Department of Agriculture-Natural Resources Conservation Service Ohio Phosphorus Risk Index (Ohio P Index). The goal is to accurately assess the risk of offsite phosphorus transport and to integrate additional management options that may help reduce offsite phosphorus transport. Delivery of the revised P Index as an interactive Web-based tool will allow for easy calculation of P Index scores and evaluation of management options to reduce phosphorus runoff risk.

Some management practices being evaluated include tillage, soil type, fertilizer placement, soil phosphorus content, field topography, water infiltration, drainage control structures and cover crops.

Key points:

• Phosphorus is the agricultural pollutant most often implicated in the degradation of Ohio fresh surface water quality and a major contributor to harmful algal blooms.
• Increased risk of phosphorus transport into surface water is associated with excessive and/or poorly managed phosphorus applications.
• Agricultural phosphorus runoff into Ohio waters harms the state’s economy in terms of fishing, recreation and drinking water sources.
• Reducing agricultural nutrient runoff in Ohio should be beneficial to farmers by reducing input costs while protecting water quality.
• The Ohio P Index is an integral part of nutrient management plans for both manure and commercial fertilizer application.