This is accomplished by conducting water directly to individual plants instead of providing water to the entire Garden area, as with flood or sprinkler irrigation. A wetted profile develops in the plant's root zone as shown in Figure 1. Its shape depends on soil characteristics. Ideally, the area between crop rows is dry and receives moisture only from incidental rainfall. Drip irrigation saves water because only the plant's root zone receives moisture.
Little water is lost to deep percolation if the proper amount is applied.
Water that passes below the root zone and eventually to the water table is lost to the plant. It is useful only for leaching or removing salts from the soil profile. Leaching also removes nutrients and therefore should be minimized. This is easily accomplished with drip irrigation. Idealized wetted profile below a trickler or an emitter.