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United States Department of Agriculture

Agricultural Research Service

Title: Determination of Phosphorus Retention and Flux in Soil.

Author
item Dao, Thanh

Submitted to: Southern Association of Agricultural Scientists Bulletin of Biochemistry and Biotechnology
Publication Type: Experiment Station
Publication Acceptance Date: September 1, 2001
Publication Date: January 18, 2002

Interpretive Summary: Uncontrolled discharges of manure nutrients from animal feeding facilities and manure storage areas, and repeated land application of manure can result in excessive phosphorus (P) concentrations in soils and losses of P to the environment. These non-point source discharges of agricultural P, along with other manure components can cause accelerated eutrophication of nearby lakes and streams. The process lowers the esthetic value and the quality of the water body for recreational and drinking purposes while poses potential risks to the watershed and human health. To address this nationwide problem we need to better understand the transformation processes and the movement of P compounds in the soil and water environment. In soil, dissolved reactive P compounds are taken up by plants, sequestered in soil, or transported across the landscape and potentially reach surface water bodies. A laboratory procedure was described in the paper for estimating the retention capacity of a particular soil for phosphate-P and the characteristics of the movement of the P with the water moving through a soil column.

Technical Abstract: In soils and sediments, physicochemical and biological processes act jointly to control the amount of phosphorus (P) that is in solution. The dissolved reactive P fraction is taken up by plants, sequestered in soil, or disperses in the surrounding environment. Typical methods used for assessing the environmental behavior of native and added P in terrestrial and aquatic ecosystems include procedures for measuring the retention capacity of soils and sediments and the associated kinetic parameters. A flow displacement method, calculation, and interpretation of breakthrough results are described herein. Flow methods are open systems where solute and the reaction products with soil/sediment constituents are removed and insure that re-adsorption, secondary precipitation reactions, or inhibition of desorption are minimized. Important parameters include water flux, dispersion, sorption, exchange and desorption characteristics, and decay or formation rates coefficients. Miscible displacement studies can provide valuable insights in the kinetics of P release and physical and chemical non- equilibrium conditions that may influence nutrient mineralization and transport in soil.

Last Modified: 4/24/2014
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