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Tiny Tips for Drought Why Mulch? Mulching can benefit water use by improving soil structure. Soils higher in organic matter have a higher capacity to retain moisture. If possible, mulch the tree-line (after the frost danger period has passed) and irrigate the soil shaded by the tree and not out in the traffic row area. If mulching with straw is possible, especially for young trees, irrigation emitters are best put under the straw next to each tree. It is important to keep the amount of exposed wetted surface to a minimum. (Source: Dry Season Information: Apples, AG1034 (PDF 80Kb) and Guide to best practice water management - orchard crops, Page 71 ) Why Night Irrigation? Irrigating at night will significantly reduce the amount of water lost to evaporation from the soil surface. A check of the FruitCheque Weather website indicates that Swan Hill pan evaporation in January can average 8 mm/day. (Source: Drought Preparation and Survival Guide, - Horticulture, 2002 and FruitCheque Weather Website.) Why No Wind Irrigation? Windy conditions increase the rate of evaporation. According to the laws of physics the faster the water molecules are removed the faster they will be replaced by more. Hence wind has the effect of increasing evaporation by facilitating this effect. Wind also ruins the distribution pattern of sprinklers. (Source: Wikipedia.) Why Shorter Irrigations? Avoid over watering your crops. Over watering cause water to escape into the water table. That water is wasted or can lead to other problems such as root rot, oxygen deficiency, salinity or other nutrient imbalances from concentrating or washing them out. Your soil can act as a reservoir of water but it is not a bank! Days between irrigations cannot be doubled simply by doubling the amount of water being applied during one irrigation. See other documents on RDI, Water Needs for Stone Fruit, Water Needs for Pears, Water Needs for Apples and Soil Moisture Monitoring for more specific information. (Source: Drought Preparation and Survival Guide, - Horticulture, 2002) Wind Break Water Use Simply multiply the length in metres of the windbreak by the flow rate per metre of the irrigation tube to find out how much water your windbreak use's. In extreme water shortages wind breaks should be sacrificed. Many will still offer protection from wind even while they are dead or dying. Wind breaks planted with natives may compete with you crop. Consider using a ripper to prune the roots, being careful not to make them unstable. Natives will, as a general rule withstand periods of low moisture availability. If you have windbreaks planted with non-drought tolerant species it may be an opportunity to plant them or build non vegetative wind structures. A quick calculation should indicate the amount of water used by windbreaks. |
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© The State of Victoria, 1996 - 2008.
This document was published on 04/09/2008.