605-4 Soil and Phosphorus Source Effects on Phosphorus Buffering Capacity.

See more from this Division: S11 Soils & Environmental Quality
See more from this Session: Nutrients and Soil Structure: I (includes Graduate Student Competition)

Monday, 6 October 2008: 8:45 AM
George R. Brown Convention Center, 361AB

Angela M. Ebeling1, Larry Bundy2, Joel G. Davis3 and Daniel Ebeling3, (1)Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA
(2)University of Wisconsin-Madison, Madison, WI
(3)Chemistry, Wisconsin Lutheran College, Milwaukee, WI
Abstract:
The use of phosphorus (P)-based nutrient management planning makes it important to understand the effects of P additions from various sources on changes in soil P status as measured by soil P tests.  The impact of P inputs and removals on soil test P (STP) status is often expressed in terms of the soil P buffer capacity (PBC), which describes the amount of P removal or addition necessary to achieve a one-unit change in STP value.  The objectives of this study were: 1) to determine soil PBC values where P is added in dairy manure, biosolids, and inorganic P and 2) to determine differences in PBC of several Wisconsin soils.  An incubation was performed in which potassium phosphate, dairy manure, and a biosolid were applied at 110 kg total P ha-1 to four soils representing major soil groups in Wisconsin.  Differences between soils were evaluated using Bray P1, Mehlich 3P, water extractable P, degree of phosphorus saturation, and PBC.  The P fertilizer had the lowest PBC (3-5 kg P ha-1) and the biosolid produced similar or slightly higher PBC values than the dairy manure (7-11 kg P ha-1 for the biosolid and 6-9 kg P ha-1 for the diary manure).  Additionally, PBC differed among the soils used, and changes in STP were related to initial STP level but not to P source characteristics such as WEP, TP, or the molar ratio of P to Fe and Al.  These data validate the need to incorporate PBC values that are appropriate to specific P sources and soils for Wisconsin P Index runoff risk calculations.  Accurate PBC values will also improve fertilizer recommendations and should provide better economic and environmental resource management.

See more from this Division: S11 Soils & Environmental Quality
See more from this Session: Nutrients and Soil Structure: I (includes Graduate Student Competition)