Chapter 8 - ETc under soil water stress conditions
Chapter 9 - ETc for natural, non-typical and non-pristine vegetation
Chapter 10 - ETc under various management practices
Chapter 11 - ETc during non-growing periods
In well-managed fields, the standard conditions are generally the actual field conditions. The ETc calculated by means of the procedures described in Part B is the crop evapotranspiration under the standard field conditions.
Where the conditions encountered in the field differ from the standard conditions, a correction on ETc is required. Low soil fertility, salt toxicity, soil waterlogging, pests, diseases and the presence of hard or impenetrable soil horizons in the root zone may result in scanty plant growth and lower evapotranspiration. Soil water shortage and soil salinity may reduce soil water uptake and limit crop evapotranspiration. The evapotranspiration from small isolated stands of plants or from fields where two different crops are grown together or where mulches are used to reduce evaporation may also deviate from the crop evapotranspiration under standard conditions.
This part discusses the effect on ET of management and environmental conditions that deviate from the standard conditions. The environmental effects are described by introducing stress coefficients and by adjusting Kc to the field conditions.