How does subsurface drainage promote better plant growth on poorly drained soils?
Subsurface or “tile” drainage removes excess water from the soil-water that prevents air and oxygen from getting to plant roots. Without artificial drainage, plants have difficulty establishing a healthy root system on poorly drained soils. Subsurface drainage provides the mechanism for these soils to drain to field capacity in a reasonably short period of time so that plant growth is not significantly impaired. In addition, drainage often permits spring field operations (e.g., tillage, planting) to take place in a more efficient and timely way. Depending on seasonal rainfall, this can have the effect of adding days, to a week or more, to the length of the growing season, providing another source of potential crop yield improvement. Does subsurface drainage remove plant-available water from the soil? No, drainage does not increase or decrease plant- available water in the soil profile. Drainage removes “drainable” water from the soil the same way a potted plant with a hole in the botto