In furrow irrigation, the surface of the soil is shaped into rows of ``furrows,'' U or V-shaped banks in the soil. Furrows are separated with ridges, upon which crops are planted. Depending on the size of ridges, only about half of the surface is covered with water, resulting in less loss due to evaporation. Furrows are generally sloped to promote gravity-driven water distribution.
The application and distribution of water for furrow systems is very similar to surface irrigation. Water partially flows downward, under the furrows themselves, and sideways, into the ridges. However, because there is no water flowing over the ridges themselves, evaporation of the water leads to saline deposits on the ridges. Salination can hinder seed germination and reduce crop growth. For this reason, furrow irrigation is often rotated with other forms to facilitate leaching and removal of salt accumulations (Hillel, 1987).