Manure is a valuable source of P for crop production. However, applying too much manure P,
especially in the wrong place, is not only agronomically wasteful, but potentially harmful to the
environment. As a result of recent increases in Manitoba’s production of livestock, the risk of
transfer of manure P from agricultural land to surface water is probably increasing. However,
the amounts of P that are discharged from livestock production and other agricultural activities
are very difficult to determine due to a lack of hydrological data and, more important, a lack of
data on the transfer of P from soil to water. Part of this problem is due to the highly variable
impact of soil type, P management, landscape and climate on P retention and release by soil,
information that is not well documented for Manitoba conditions. Fortunately, livestock
producers have a wide variety of potential techniques for reducing P discharge from their
operations; however, the technical and economic merit of these techniques is generally not well
documented either, for Manitoba conditions. As a result of these challenges, legislation and
regulation regarding P management should be introduced cautiously to ensure environmental
protection without undue hardship to the agricultural industry.