This study was funded by the Canadian Fertilizer Institute and ARDI and is ongoing. One of the things that we are exploring in this study is to compare simple soil test P with the newly formulated degree of phosphorus saturation (DPS) as measures of risk of P loss in runoff from Manitoba soils. Previous studies have shown that the DPS is superior to soil test in measuring the risk of P loss from different soils. However, our preliminary results have shown that for Manitoba soils this may not be so. We have so far obtained better relationships between the amount of P loss in runoff and soil test P compared to DPS. Therefore, further studies will be needed to refine the DPS of Manitoba soils, especially in soils with a history of manure application. The advantage of DPS (over simple soil test P) is that it can be used to define objectively a threshold beyond which the application of phosphorus to soils will not be advisable if the loss of P is to be minimized. Also the runoff studies that we have carried out so far have been in the laboratory using rainfall simulation. We will like to carry out similar studies in the field using rainfall simulation on representative Manitoba soils.