The
Net Irrigation Requirement is defined in the GWPA Regulations
as: "the amount of water needed to bring the soil
in the crop root zone to field capacity
at the time of irrigation. It can be determined by direct
soil moisture measurements of soil moisture, such as by
using tensiometers, or indirect measurements of soil moisture,
such as by estimating evapotranspiration that has accumulated
since the last irrigation."
The definition states that the Net Irrigation Requirement
can be determined by direct soil moisture measurement
and by estimating crop water use (evapotranspiration)
since the last irrigation. The following 2 subsections
"Direct Soil Moisture Measurement" and "Estimating
Crop Water Use" provide detailed guidance on determining
the Net Irrigation Requirement.
