Where irrigation applications do no

Where irrigation applications do not equal evapotranspiration requirements, precipitation of the least soluble salts in the water occurs within the root zone as the plants extract water. The plants will extract the maximum amount of water because they are underirrigated, i.e., less than the required average amount of irrigation water is applied. The rate of accumulation of salt precipitating in" the root zone depends on the relative amount of salt in the irrigation water and the proportion of the applied water that is consumed by the plants. Before the soil pores become clogged with precipitated salt, crop production will be reduced by the increasing salt concentration in the root zone due to the resulting increased solute potential or osmotic pressure. A high salt concentration in the root zone reduces the effective availability of water to the plants.Continued application of the theoretical evapotranspiration water requirement would therefore begin to result in a deep percolation water loss at some relatively high salt concentration and the establishment of a new dynamic salt inflow-outflow equilibrium with continuing precipitation of salt in the root zone.