Temperature affects the rate of nutrient leaching by controlling how water moves through the soil and how active plants and microbes are. During periods of warm weather, even in winter, melting snow or rainfall can produce enough liquid water to carry nitrogen and other soluble nutrients downward through the soil profile.
Cold temperatures slow the biological activity that normally holds nutrients in place, since plants are not taking them up and soil microbes are far less active. So if the soil is thawed or partially thawed, water can percolate downward rather than running off, allowing nutrients to move toward groundwater. Sudden shifts from freezing to mild conditions can even create a temporary window where water moves freely while the soil structure is still disrupted from freezing.
