Irrigation performance and water use efficiency of turf production

Abstract

[Abstract]: Turf water requirements on the Darling Downs have never been analysed and it is the purpose of this project to find the minimal water requirements to grow turf for production use. The water quantity will be measured from the initial bare soil to the date of cutting the turf. The minimum water requirement is the amount needed to sufficiently provide the sustained growth at a certain quality needed to sell the turf to the public. The irrigation application rates must be small enough that there is no water lost through deep drainage. The two turf species that were investigated were wintergreen couch and kikuyu. The project was designed to remedy many issues, the first was the low distribution uniformity produced by the in ground solid set sprinkler system at the business of Cabarlah Park Turf. Both Cu and Du figures were found by performing a number of catch can tests while pressure performance at pump and nozzle. Recommendations of how to fix the low uniformity were then put forward to the grower. These recommendations were carried out and further catch can tests were carried out to see what kind of improvements were made to the distribution uniformity of the system. Using the catch can data, each part of the trial site had a known amount of irrigation application per hour. The required irrigation times were calculated using daily ETo figures from the on site weather station. From this point the value was multiplied by a relative crop factor and the application amount was able to be received. The amount of hours that the irrigation was run was logged and the quantity of water that each part of the trial site received for the entire growth period was calculated. The turf was evaluated using a one to nine scale for strength and colour. Evaluations on which turf received the greatest ratings at the lowest water quantity were undertaken. The results showed a low distribution uniformity of 52.4% which was improved to 57% after the distribution enhancement recommendations were carried out. The wintergreen couch was able to be grown with a minimum water requirement of 392mm over a period of a month and a half. The kikuyu trial had to be abandoned due to a pump break down for most of it’s growth period therefore there was no minimum water requirement found for kikuyu during this project. The project showed that there could be significant savings in water use by initiating an irrigation application rate derived from ETo calculations. Soil moisture meters showed that there could be further improvement to water saving, for the purpose of turf production. The results showed that uniformity must be increased to see any decrease in yield loss.