15. Water and Energy Balance in the Field and Soil-Water Regimen

Management of soil water to optimize biomass production is the primary aim of amelioration activities. Soil-water management, i.e. the design and operation of irrigation and drainage systems in the field have to be based on diagnoses of soil-water regimen. The soil-water regimen is a statistical characteristic of individual (mostly annual) cyclic courses of soil water (or soil-water matric potential); it is the generalisation of the individual annual courses by processing long-time (many years) average values of regimen characteristics. Then, the type of soil-water regimen and ways to manage it can be proposed and an expected yield can be calculated. Based on analysis of soil-water balance equations, one can propose the principles of soil-water management. Hydrological classification of the soil-water regimen and the principles of soil-water regimen diagnostics are presented.