Advantage of tile drainage: Tile drainage helps in increasing crop yields by draining the water or by lowering the watertable in the following manner: (i) Removes the free gravity water that is not directly available to the plants. (ii) Increases the volume of soil from which roots can obtain food. (iii) Increases air circulation. (iv) Increases bacterial activity in the soil, thus improving soil structure and making the plant food more readily available. (v) Reduces soil erosion. A well drained soil has more capacity to hold rainfall, resulting in less runoff and hence, reduced erosion. (vi) Reduces and removes toxic substances such as sodium and other soluble salts, which when present in large concentrations may retard plant growth. (vii) Lesser time and labour is required for tilling and harvesting the soils, as these drains do not obstruct farming operations. With a crop such as corn, a delay in planting may decrease the yields. Planting in wet soils is also likely to decrease yields. AH such troubles are removed in tile drained soils. (viii) Tile drains permit deep roots development by lowering the watertable, especially during spring months.