Predicting deep drainage in the soil from soil properties and rainfall

Abstract. Simple predictions of deep drainage in the soil profile are often required for preliminary planning of land management where the cost of direct measurement is not warranted. Soil hydraulic conductivity and drainage of water below the root zone can be related to the salt content at the bottom of the root zone, assuming steady-state balances of water and salt. A physically based empirical model uses readily measured soil properties to predict the quantity of drainage below the root zone under varying regimes of water management and shows a good relationship with ponded infiltration rate.