[03 May/Farmers Weekly]

AgResearch senior scientist Dr Val Snow and Auckland University acoustics physicist Professor Stuart Bradley have found that directing sound signals at soil could ultimately help improve its health, reduce nutrient losses and save farmers money. They have been researching how sound waves can be used to determine optimal irrigation levels with the technology Surface Water Assessment and Mitigation for Irrigation (SWAMI), which is being used to define a relationship with sound waves bouncing off the soil surface and controlling irrigation applications. Dr Snow reported the traditional means of determining optimal irrigation levels cannot take account of the free water that ponds on the soil surface. The patented technology developed in the joint venture is still in its early stages but researchers are starting to find an algorithmic relationship between the signal change and the amount of ponded water on the soil.