Advance rate measurement for furrow irrigation

Abstract

Furrow irrigation is used for 96% of the irrigated cotton crop area in Australia. The performance of furrow irrigation can be improved by measuring furrow irrigation advance rate, from which optimised values for irrigation parameters can be determined and implemented in subsequent irrigations. Most water detection methods for advance rate measurement use water sensors that are located in the furrow, and which must be tediously collected from the furrow after the irrigation takes place. Design of an alternate system for advance rate measurement has emphasised convenient, immediate recovery of advance data. Machine vision was investigated as an approach for measuring advance rate for furrow irrigation. A high resolution digital camera at a fixed location at the end of the field monitors changes in field appearance during an irrigation. In the absence of a crop canopy, an unobstructed view of the advancing water front can be obtained from the end of the field. For more mature crops, under certain conditions, change in crop canopy appearance during an irrigation also travels visibly down the field. The digital camera has been interfaced with a laptop so that images can be captured, downloaded and analysed during the irrigation. Field trials indicate that a single camera can detect objects for distances up to 500 metres with an accuracy of + or - 5 metres, by use of optical zoom and by increasing the height of the camera. Experiments reveal significant tonal response of dry crop plants to water within twenty minutes of application of water. The image analysis involves two separate approaches for the bare soil and closed canopy conditions. Temperature sensing of soil and crop canopy temperature was considered in conjunction with the digital camera advance front detection, however due to budgetary constraints thermal response of the field could not be investigated for this project.