How Much Water?
When To Irrigate?
On sand, because of the low moisture holding capacity, it’s best not to apply more than about 6 mm in any one irrigation, so split the watering into two shifts. Ideally one shift early using off-peak power before 8 am in summer and the other around the middle of the day, assuming water quality is good.
In summer because average evaporation is high (greater than 7 mm/day), irrigation is applied daily, sometimes 2 or 3 times. However in winter when evaporation is low (average is close to 2 mm/day), a ‘deficit’ of irrigation requirement can be allowed to accumulate before applying water. In winter on yellow sands this deficit can be allowed to reach 8 mm for an established crop. In winter some anticipation of rain from weather forecasts should also be factored into irrigation management.
On sandy soils it is necessary to apply irrigation during periods of high wind to prevent wind erosion damage to sensitive crops. Irrigation for frost control may be required on occasions for frost sensitive crops such as potatoes mainly in the months from June until September.
