Surface irrigation methods.

There are three general methods of applying irrigation water to the land.

In the surface irrigation the water either is ponded on the soil or allowed to flow continuously over the soil surface for the duration of the irrigation.

In sprinkler irrigation the water is conveyed above the field in pipes, and the soil acts as a storage reservoir.

In subirrigation the water flows underground, and the capillary water moves upward toward the surface of the land.

Surface irrigation includes the general methods of flood and furrow and corrugation irrigation. (1)

In flood irrigation, water is permitted to cover the surface of the land in a continuous sheet. (2)

Flood irrigation includes several methods: border strip, basin, contour or bench border irrigation, wild flooding and others. (3)

The object of border strip irrigation is to advance a sheet of water down a narrow strip between low ridges or borders and to get the water into the soil as the sheet advances. The ridges should be low and rounded so they can be planted with the strips and no land lost to production.

Border strip irrigation is well adapted for all close – growing crops and is used for some row crops, such as cotton.

Basin irrigation is adapted especially to flat lands. It consists of quickly filling a diked area with water to the desired depth and allowing the water to percolate into the soil. It is desirable for close – growing crops and orchards and for rice.

Contour, or bench border, irrigation is adapted to fairly uniform, moderate slopes. Border strips are laid out across the slope and the ridges are constructed parallel to each other.

In wild flooding the stream of water is diverted from its course and allowed to spread out over the field at random. It is not recommended, because the low spots in the field will get too much water and the high spots will receive none.

Furrow irrigation is the most common method of applying water to row crops. Water is applied in the furrows between the rows of plants. As water runs down the row, parts of it is being absorbed all along the furrow. It is adapted to all row crops, truck crops, orchards, vineyards, and berry patches on gentle slopes.

Corrugation irrigation is well adapted to close – growing crops on sloping lands and to soil slow to take water. The water is applied in small furrows running down the slope from the head ditch. Corrugation irrigation provides uniform wetting and prevents erosive water accumulation on land too steep for borders or basins and make use of small irrigation streams.