HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Casson, J. P. Articles by Ontkean, G. R. Search for Related Content PubMed PubMed Citation Articles by Casson, J. P. Articles by Ontkean, G. R. Agricola Articles by Casson, J. P. Articles by Ontkean, G. R. Related Collections Surface Water Quality Runoff Phosphorus

TECHNICAL REPORTS

Surface Water Quality

Degree of Phosphorus Saturation Thresholds in Manure-Amended Soils of Alberta

^a Alberta Agriculture, Food and Rural Development, 100, 5401 1st Avenue South, Lethbridge, AB, Canada T1J 4V6
^b Alberta Agriculture, Food and Rural Development, 206, 7000 113 Street, Edmonton, AB, Canada T6H 4Z9

^* Corresponding author (janna.casson{at}gov.ab.ca)

Received for publication February 28, 2006. The risk of P losses from agricultural land to surface and ground water generally increases as the degree of soil P saturation increases. A single-point soil P sorption index (PSI) was validated with adsorption isotherm data for determination of the P sorption status of Alberta soils. Soil P thresholds (change points) were then examined for two agricultural soils after eight annual applications of different rates of cattle manure and for three agricultural soils after one application of different rates of cattle manure. Linear relationships were found between soil-test P (STP) levels up to 1000 mg kg^–1 and desorbed P in the five Alberta soils. Weak linear relationships were also found between STP and runoff dissolved reactive phosphorus (DRP) in three of these soils. Change points for the degree of P saturation (DPS) were detected in four of the five soils at 3 to 44% for water-extractable P (WEP) and at 11 to 51% for CaCl₂–extractable P (CaCl₂–P). Change points were not found for DPS or runoff DRP. Overall DPS thresholds for the five soils combined were 27% for WEP and 44% for CaCl₂–P at a critical desorbable-P value of 1 mg L^–1. The corresponding STP levels (44 mg kg^–1 for WEP and 71 mg kg^–1 for CaCl₂–P) are similar to agronomic thresholds for crops grown on Alberta soils. Soluble P losses in overland flow and leaching may be greater in soils with DPS values that exceed these thresholds than in soils with lower DPS values.

Abbreviations: CaCl₂–P, calcium chloride extractable phosphorus • DPS, degree of phosphorus saturation • DRP, dissolved reactive phosphorus • PSC, phosphorus sorption capacity • PSI, phosphorus sorption index • STP, soil test phosphorus • WEP, water-extractable phosphorus

This article has been cited by other articles:

				J. L. Little, S. C. Nolan, J. P. Casson, and B. M. Olson Relationships between Soil and Runoff Phosphorus in Small Alberta Watersheds J. Environ. Qual., July 17, 2007; 36(5): 1289 - 1300. [Abstract] [Full Text] [PDF]

				C. A. Volf, G. R. Ontkean, D. R. Bennett, D. S. Chanasyk, and J. J. Miller Phosphorus Losses in Simulated Rainfall Runoff from Manured Soils of Alberta J. Environ. Qual., April 5, 2007; 36(3): 730 - 741. [Abstract] [Full Text] [PDF]