You will have to work out the the available water content of the soil (AWC) , and accordingly , you will have to impose treatments based on depletion of 10%, 20% , 30% , 40% etc of AWC, keeping in mind the daily evaporation rate, to cover both wet and dry soil moisture level . these levels could finally be cross verified either through gravimetric soil moisture content or using moisture sensors , including neutron moisture probe...