TY - JOUR
AU - Sims, J. T.
AB - The role that soil testing can play in identifying agricultural soils with an increased potential for P loss is an important topic. Our research compared the Mehlich 3 P saturation ratio (M3‐PSR) with the ammonium oxalate degree of P saturation (DPSox), and the M3‐PSR was then evaluated for predicting agronomic and environmental soil P saturation thresholds. Intact soil columns (15‐cm diam, 20 cm deep) and soil samples were collected from five soil series that ranged in soil texture, chemical properties, and Mehlich 3 P. The soils were analyzed for pH, organic matter (OM) and oxalate and Mehlich 3 extractable P, Al, and Fe. Each intact column was leached with the equivalent of 5 mm of rainfall and resulting leachate analyzed for P. Mehlich 3 extractable Al, Fe, and P were closely related to oxalate extractable Al, Fe, and P, although Mehlich 3 extracted only a small amount of Fe compared with oxalate. The M3‐PSRs, calculated as the molar ratios of Mehlich 3 extractable P/[Al + Fe] (ratio I) and P/Al (ratio II), were well correlated to each other and to DPSox All three P saturation measurements showed a threshold or change point above which the concentration of P in column leachate increased rapidly. Both the agronomic optimum M3‐PSRs and the environmental limit suggested in the Netherlands for DPSox (25%) were below the observed change point. The M3‐PSR measured in a single Mehlich 3 extraction shows excellent promise for identifying soils that represent an increased risk for P leaching losses.
TI - Measuring Agronomic and Environmental Soil Phosphorus Saturation and Predicting Phosphorus Leaching with Mehlich 3
JF - Soil Science Society of America Journal
DO - 10.2136/sssaj2002.2033
DA - 2002-11-01
UR - https://www.deepdyve.com/lp/wiley/measuring-agronomic-and-environmental-soil-phosphorus-saturation-and-GHvC9onsv7
SP - 2033
EP - 2039
VL - 66
IS - 6
DP - DeepDyve
ER -