The concluding phase(s) of a rice rotation experiment presented the opportunity to assess the
effect of consecutive crops of rice on the chemistry of the soil profile.
An experiment which aimed to determine the potential to use high salinity groundwater for
the irrigation of the non-rice phases of a wheat - sub.clover - rice rotation, and then use rice,
irrigated with low salinity channel water (<0.1 dS/m), as a leaching crop was undertaken.
The rotation included a single rice crop between each cycle of the application of saline
Although soil salinity of most horizons under saline treatments could be reduced by leaching
in the rice phase (single crop), this was not true for sodicity. Average rootzone sodicity
remained elevated above control values at the end of each cycle and increased following
This project was implemented to further assess the effectiveness of rice as a leaching crop. As
the blocks completed two cycles within the rice rotation the opportunity to grow successive
crops of rice was undertaken. At the time of soil sampling (May, 2000) separate blocks had
grown one, two, three or four consecutive rice crops. Soil samples were taken from each plot
and processed for electrical conductivity and sodium (Na) content.
Additional consecutive crops of rice resulted in more leaching of salt from the profile. After
three crops sufficient salts had been leached to reduce ECe to below 0.6 dS/m to at least the
depth sampled in this project (90 cm). Similar values were measured after a fourth crop.
The levels of SARe measured after a second consecutive crop of rice were still higher than
pre-treatment levels. Even after three and four crops of rice the SARe at profile depths below
60 cm, whilst reduced from the pre-treatment level, were still between 6 and 8.