The way the cotton plant responds to water stress on different soil types changes will influence its requirement for water and may change the irrigation strategy used if yield potential is to be achieved. Soil types are different not only in the total amount of available moisture that they hold, but also in how readily the moisture is made available to the plant. This response has been investigated in a three year project measuring plant water stress under different irrigation conditions during early flowering on three soil types. Initial interpretation of results suggests that plants differ in their response to soil moisture stress on light soils compared with heavier soils, when using a standardized measurement of soil moisture status i.e. the fraction of transpirable soil water (FTSW). FTSW is calculated by changing available water content of the soil to a percentage. The advantage of using FTSW to define soil moisture holding capacity is that it allows people working across different known soil types to compare soil types in terms of irrigation schedule and plant moisture availability.