Irrigation controlled by a wetting front detector: field evaluation under sprinkler irrigation
R. J. Stirzaker A and P. A. Hutchinson BA Corresponding author. CSIRO Land and Water, PO Box 1666, ACT 2601, Australia. Email: Richard.stirzaker@csiro.au
B CSIRO Land and Water, Private Bag 3, Griffith, NSW 2680, Australia.
Australian Journal of Soil Research 43(8) 935-943 https://doi.org/10.1071/SR05005
Submitted: 7 January 2005 Accepted: 8 August 2005 Published: 8 December 2005
Abstract
The accuracy of scheduling irrigation to turf by sprinkler was evaluated using a simple wetting front detector that automatically switched the water off after the wetting front had reached a prescribed depth in the soil. The detector consists of a funnel-shaped container that is buried in the soil. When a wetting front reaches the detector, the unsaturated flow lines are distorted so that the water content at the base of the funnel reaches saturation. The free water produced is detected electronically and this provides the signal to stop irrigation. The performance of the detector was evaluated over 38 consecutive irrigation events to test the theory that the velocity of a wetting front depends on the difference in water content ahead of and behind the front. The experimental data plotting the irrigation amount permitted by the wetting front detectors as a function of the soil water content before and after irrigation yielded a linear relationship with a slope of 0.95 and a correlation coefficient of 0.73. Thus, if the soil is dry before irrigation the front will move slowly and an irrigation of long duration will be permitted, with the converse applying to wet soil. Independent monitoring of soil water content showed that irrigation was, for the most part, scheduled accurately. Irrigation interval was the key variable to control. When the interval was too short then over irrigation occurred.
Additional keywords: irrigation scheduling, soil moisture sensors, irrigation interval, irrigation uniformity, soil water content.
Acknowledgments
We thank Chris Drury for assisting with the field electronics, Chris Smith and Evan Christen for helpful comments on the manuscript and 3 insightful reviewers.
Ahuja LR, Nielsen DR
(1990) Field soil-water relations. ‘Irrigation of agricultural crops’. Agronomy Monograph No. 30.,(Eds BA Stewart, DR Nielsen)
pp. 144–190. (ASA-CSSA-SSSA: Madison, WI)
Augustin BJ, Snyder GH
(1984) Moisture sensor controlled irrigation for maintaining bermudagrass turf. Agronomy Journal 76, 848–850.
Cary JW, Fisher HD
(1983) Irrigation decisions simplified with electronics and soil water sensors. Soil Science Society of America Journal 47, 1219–1223.
Charlesworth, PB (2005).
Connellan G
(2004) Performance benchmarking of turf and landscape irrigation systems. ‘Irrigation Australia 2004 Conference’. 11–13 May 2004, Adelaide. (The Irrigation Association of Australia Ltd)
Evett S, Laurent J-P, Cepuder P, Hignett C
(2002) Neutron scattering, capacitance, and TDR soil water content measurements compared on four continents. ‘17th World Congress of Soil Science’. 14–21 August 2002, Bangkok. (IUSS: Bangkok)
Hutchinson PA, Stirzaker RJ
(2000) A new method and device for scheduling irrigation. ‘Irrigation Association of Australia 2000 National Conference’. 23–25 May 2000. (The Irrigation Association of Australia Ltd)
McKenzie N, Henderson B, McDonald W
(2002) Monitoring soil change. Principles and practices for Australian conditions. CSIRO Land and Water Technical Report 18/02.
Pathan SM, Barton L, Colmer TD
(2003) Evaluation of a soil moisture sensor to reduce water and nutrient leaching in turf. Final Report to Horticulture Australia.3. http://www.fnas.uwa.edu.au/__data/page/17750/Final_report_for_HAL_project_TU02006.pdf
Philip JR
(1957) The theory of infiltration. 2. The profile at infinity. Soil Science 83, 435–448.
Philip JR
(1969) Theory of infiltration. Advances in Hydroscience 5, 215–296.
Rubin J, Steinhardt R
(1963) Soil water relations during infiltration. I. Theory. Soil Science Society of America Proceedings 27, 246–251.
Schmitz M, Sourell H
(2000) Variability in soil moisture measurements. Irrigation Science 19, 147–151.
| Crossref | GoogleScholarGoogle Scholar |
Stirzaker RJ
(2003) When to turn the water off: scheduling micro-irrigation with a wetting front detector. Irrigation Science 22, 177–185.
| Crossref | GoogleScholarGoogle Scholar |
White I,
Smiles DE, Perroux KM
(1979) Absorption of water by soil: The constant flux boundary condition. Soil Science Society of America Journal 43, 659–664.
Zegelin SJ,
White I, Jenkins DR
(1989) Improved field probes for soil water content and electrical conductivity using time domain reflectometry. Water Resources Research 25, 2367–2376.
Zur B,
Ben-Hanan U,
Rimmer A, Yardeni A
(1994) Control of irrigation amounts using the velocity and position of wetting front. Irrigation Science 14, 207–212.
| Crossref | GoogleScholarGoogle Scholar |
