Location: Soil Drainage Research
Project Number: 5080-13210-003-045-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 15, 2026
End Date: Aug 14, 2029
Objective:
Identify the influence of soil carbon-to-nitrogen-to-phosphorus (C-N-P) ratios on soil P and runoff P dynamics across multiple research sites in Ohio and Indiana. The Cooperator will assess multiple soil P fractions (soil test phosphorus (STP) and dissolved reactive phosphorus (DRP)) and soil C and N concentrations in fields containing excess P from years of P fertilizer application (i.e., legacy P-containing fields). The soil measurements will be paired with on-going water quality measurements (runoff P concentrations and loads) to explore potential relationships between soil P cycling dynamics and water quality impacts. The research will enhance understanding of the dynamics of storage of P in soils, and of the drivers of agricultural P losses and how to mitigate them, from legacy P-containing fields.
Approach:
The cooperator will utilize USDA-ARS soil archives, supplemented with to-be-collected soil samples from USDA research sites, to quantify soil C, N, and P ratios and fractions (e.g., total C, inorganic C, total N, inorganic N, STP, DRP, inorganic P fractionation). Measurements will involve well-established soil P fractionation procedures, analysis of C and N via combustion analyzers, and analysis of P and other metals by inductively coupled plasma (ICP) spectrometry. Additional analysis of the soil samples (e.g., amorphous soil Al and Fe presence, clay mineralology, texture) will be employed when necessary using established laboratory protocols.