Increasing concern about the falling water quality associated with phosphorus from agricultural soils calls for urgent regulation of phosphorus application to soil. Such regulation requires the use of an appropriate risk indicator method and the establishment of threshold limits beyond which phosphorus input to agricultural soil becomes unacceptable. The degree of phosphorus saturation is one of the methods that have been used in phosphorus loss risk assessment and some regulatory limits are available for acid soils. Such limits are not available for neutral to calcareous soils of Manitoba, Canada. The objective of the study is, therefore, to evaluate the applicability of the degree of phosphorus saturation in assessing the risk of phosphorus loss from soil to surface water in neutral to calcareous soils of Manitoba and to establish an environmental threshold for the degree of phosphorus saturation in these soils. The method for estimating the degree of phosphorus saturation in neutral to calcareous soils and the degree of phosphorus saturation limits for these soils will be presented.