To maintain the pasture in a good condition and achieve the
restoring objectives, irrigation amounts in different periods should
be calculated.
According to Eqs. (2)–(7), the water demand by evapotranspiration
and soil are both impacted by soil water content. Therefore,
the irrigation requirements can be divided into different grades
by soil water content that are field capacity, the critical soil water
content of water stress and the wilting coefficient. Corresponding
to the three soil water contents, the irrigation quantities are the
maximum irrigation amount Wmax, critical irrigation amoun