Chemical Transport During Surface Irrigation :: Agriculture Farming Papers

Chemical Transport During Surface Irrigation Surface irrigation, the most prominent method used for irrigating agricultural crops, is the flowing of water across the field surface. As the water flows, it infiltrates into the soil. The amount of water applied to the field is regulated by the length of time that the water is allowed to flow. Surface irrigation can be subdivided into following four types based the amount of water flow control; wild flooding, graded boarders, level boarders and furrow irrigation. Wild flooding uses a series of field ditches running parallel or perpendicular to the fields' contour. Water is introduced into the field either be overflowing the ditches or by siphon. Once the water enters the field, the water is allowed to flow uncontrolled under the force of gravity. The water then infiltrates the soil as it moves across the field. The graded boarder method is similar to wild flooding except that the field is divided into a series of smaller narrower fields varying from 10 to 20 meters wide and 100 to 400 meters long. Each of these smaller fields is surrounded by a low ridge that keeps the water from spreading to much laterally. This method gives some control over the flow of water. Level boarder irrigation is similar to the graded boarder method except that the field is leveled within the low ridges surrounding it. Water can be introduced into the field at a faster rate so the field is covered much quicker. The water is then allowed to infiltrate into the soil. Furrow irrigation chanalizes the water into narrow furrows running the length of the field perpendicular to the contour of the field. This submerges only about one fifth of the soil surface. As the water flows down the furrow it infiltrates into the soil below and to the sides of the furrow. All four of these methods result in excess water being applied to the field to ensure that the far ends of the field are adequately watered. This means that there will be water running off the field on the downhill side of the field. A ditch is run along the side of the field to collect this water and remove it from the field. This excess water is of concern from a water quality standpoint. Almost all crops grown in the united states are done so under intense fertilization and pest control programs that result in large amounts of fertilizers and pesticides being applied to the soil and crop itself.