Types of deep drainage under irrigated cotton farming systems on a cracking clay soil.

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Ringrose-Voase, Anthony ORCID ID icon; Nadelko, Tony ORCID ID icon


2013-09-09


Conference Material


2013 Australian Cotton Research Conference, Narrabri, NSW, 8–11 September 2013


p. 53


Deep drainage under irrigated cotton can waste a scarce resource and lead to salinity problems if it causes watertables to rise. The magnitude, timing and process of drainage under a cotton-wheat rotation on a cracking clay has been investigated using the variable tension lysimeter at the Australian Cotton Research Institute near Narrabri since October 2006. The lysimeter allows accurate, high frequency measurement of drainage. Over the three cotton seasons for which drainage was measured, 0 to 73 mm of drainage per season was recorded. The high frequency measurements revealed there were two types of drainage – matrix and bypass. Matrix drainage occurred at relatively low rates of 0.5 mm/day over extended periods of a month during wet periods when rainfall exceeded ET causing a wetting front to move down the profile until it passed out of the root zone. Bypass flow occurred after furrow irrigation with peak rates of up to 3.2 mm/day 25 hours after irrigation. The water content and soil water potential of the soil at 1-2 m depth remained largely unaffected by the irrigation, showing that water was bypassing the soil matrix and travelling via macropores. Bypass drainage accounted for most drainage during the two year rotation. Drainage was greatest after irrigations early in the season necessitated by low, early season rainfall. Apart from lowering water use efficiency it also means a higher leaching fraction is required to prevent a build up of salt, because bypass drainage is less efficient at removing salt.


Association of Australian Cotton Scientists


Deep drainage; Irrigated cotton; Vertosols; Bypass flow


Soil Physics


Link to Publisher's Version


© Copyright 2013 CSIRO


EP139220


Conference Abstract


English


Ringrose-Voase, Anthony; Nadelko, Tony. Types of deep drainage under irrigated cotton farming systems on a cracking clay soil.. In: 2013 Australian Cotton Research Conference; 8–11 September 2013; Narrabri, NSW. Association of Australian Cotton Scientists; 2013. p. 53. http://hdl.handle.net/102.100.100/96668?index=1



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