Page 276 - Nutrient Management Planning Guide

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Factors Affecting Runoff Nutrient Losses

Runoff and water erosion can transport •

nutrients from the field either dissolved in solution or associated with soil particles reducing the amount of nutrients available to support crop production. Precipitation patterns are a major factor in •

the generation of runoff. Most of the runoff in Alberta is generated by snowmelt. Timing and rate of precipitation are critical •

factors affecting runoff. High intensity storms will cause more runoff than low intensity storms. The condition of the soil at the time of •

rainfall or runoff is also important. Wet soils generally have lower infiltration rates than dry soils since pore spaces are already filled with water.

Soil properties including texture, structure •

and organic matter content have

important influences on the permeability of a soil to water and its ability to hold water once it has infiltrated. Length and grade of slopes in a field •

impact soil erosion and therefore nutrient losses. Several runoff control practices are designed to interrupt the continuity of slopes to interfere with free-flow of runoff down slope. Ground cover in the form of vegetation •

or crop residue can reduce erosion and nutrient losses by providing a physical barrier and protecting the soil surface from the erosive energy of rainfall, snowmelt and concentrated flow.

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