Farms are especially vulnerable to nutrient runoff in winter because they tend to have bare surfaces and storage areas exposed to weather at a time when the soil cannot soak up water. Frozen ground, compacted areas around barns, and fields with little vegetation leave nutrients sitting near the surface.
When a warm spell or rain-on-snow event occurs, water flows quickly across these areas and picks up nitrogen and phosphorus that would normally be held in place by active plant growth or unfrozen soil. Manure storage structures, uncovered piles, and heavily trafficked livestock zones also face greater stress during freeze–thaw cycles, which can lead to leaks or surface wash-off.
