Evaluation of the performance of automated bay irrigation of pasture and fodder

Evaluation of the performance of automated bay irrigation of pasture and fodder

Automation of surface (bay) irrigation is a commercial reality with a number of farms in northern Victoria adopting it for whole or part of their irrigated area. Automation provides increased certainty in irrigation management. However in the absence of appropriate decision support, most of the key decisions, such as the scheduling of irrigations, flow rate and irrigation duration, still rely on the skill of the irrigator. Over the 2013/14 irrigation season the authors were engaged to evaluate the application efficiency of automated bay irrigation. The trial involved 9 farms x 1 bay x multiple irrigations. Flow rate into the bay was inferred from measurements at the supply point to the farm. Irrigation advance down the bay and flow depth were measured at three points down each bay. Soil moisture was monitored continuously at a central point in each trial bay. Data were collected automatically and stored on-line.

The results demonstrated that application efficiencies in excess of 90% are achievable and are being achieved through correct and precise management of the automated irrigation. Four of the farms evaluated in this study are already operating at that level. For another four of the farms strategies have been identified that will raise their efficiency close to or above 90%. On the remaining farm soil limitations preclude improvements in efficiency on the trial bay.

As well a number of not unexpected lessons were learnt from the trial:
1. Excessively long irrigation durations are the principal cause of low efficiencies.
2. Soil moisture data is crucial for the optimal management of irrigated pasture.
3. Pastures are deeper rooted and soils more permeable than local mythology presumes.
4. Waterlogging is a major consequence of inefficient surface irrigated pasture.
5. Less frequent irrigations and shorter durations will reduce water logging and give greater pasture productivity.

Abstract only, as supplied here, published in the Conference Proceedings. No evidence of copyright restrictions preventing deposit.