Soil structure is a key component to soil quality. Substitution of conservation tillage and no-till for conventional tillage practices greatly affects soil structure and decrease runoff and losses of soil, nutrients, and agrochemicals in overland flow. However, enhanced infiltration increases the potential for sub surface flow, especially in tile lines. Earthworm burrows, root holes, cracks and structural porosity in the soil surface can allow for rapid transport of nutrients and chemicals to tile lines.

Liquid manure has become the norm on many livestock operations. These liquid wastes are applied by surface application or incorporated with tillage or by direct injection. Because of concerns with odor and surface runoff, subsurface injection is becoming more widely used by livestock operations. The issue of liquid manure entering subsurface drainage systems is being increasingly recognized as an important environmental issue throughout drained areas in the U.S. Midwest. The combination of increased conservation tillage, increasing use of liquid manure, and deeper incorporation of liquid manure, transport of manure through soil to tile lines has become an issue.