Water is delivered to the field by the main line .
Lateral lines are attached to manifolds or sub-mains. The terms drip, trickle and spray can be merged under one term micro irrigation. Micro irrigation includes all methods of frequent water application, in small flow rates, on or below the soil surface. Ideally, the volume of water is applied directly to the root zone in quantities that approach the consumptive use of the plants. It is essential that the discharge from the emitter be uniform and that it not change significantly with small pressure variations in the system.