Irrigation efficiencies

Paper presented at South Island Dairy Event (SIDE) conference, 5-7 July 1999, Christchurch.Irrigation has been a frequently discussed subject in New Zealand for many years. A book called Practical Irrigation was written by John McKeague and published in Ashburton in 1899, 100 years ago. Although there were some small developments in irrigation from that time, it wasn't until the 1930s that state-funded irrigation schemes progressed as we know them today. All of the early schemes were surface water irrigation schemes - border strip irrigation and wild flooding. Spray irrigation was introduced on private schemes in the 1960s and later on into some of the state-funded schemes. However, even in the early 1980s the majority of the new schemes utilised border strip irrigation. The interesting thing about these developments is that the surface water irrigation systems were often constructed on soils that were likely to result in low water use efficiency. In fact, in some of the later schemes, provision was made for drainage to prevent water-logging of farms at the bottom of schemes. Using water efficiently did not appear to be high priority. The situation is changing rapidly. Irrigation efficiency is one of the key issues facing irrigation farmers and water managers in New Zealand. The general population is now much more environmentally aware than in the past and sees inefficient water use as a threat to environmental sustainability. Farmers may be forced to irrigate efficiently by being allocated water on an efficient basis. To maintain access to water, there will also be more pressure on farmers to demonstrate that they are using water effectively and efficiently. On most of the irrigated dairy farms in the South Island, irrigation is a necessary part of the farming enterprise, because without irrigation, dairy farming would not be viable in these areas. Maintaining access to water, therefore, is vital