A study into the effects of sodicity on the capping of soils
A study into the effects of sodicity on the capping of soils
The hypothesis that the development of sodicity at the soil surface might increase soil strength to give adverse effects on agricultural productivity through impaired germination and poor crop stand simulated this investigation. The study aimed to investigate the link between rising salinity and sodicity at the soil surface from saline irrigation water or capillary rise from groundwater and the development of surface cap strength as well as the effects of leaching and mechanical action on soil surface and profile strength.
Efford soil containing small amounts of expansible clay, mica, known to be prone to capping was deliberately salinised to impose a range of salinities and sodicities at the soil surface with solutions with electrical conductivities, EC's = 1, 4, 8 and 12 dS m-1 and sodium adsorption ratios, SAR's = 0, 2, 4, 6, 8, 12, 20 and 40. It was established that the strength at the surface increased during the actual salinisation process, but significantly increases in strength were almost exclusively related to the rise in sodicity. Further strengthening occurred on leaching, and this was strongly linked to the increased sodicity at the soil surface before leaching. Surface strength was lowest for the non-sodic soil (550 kN m-2) but increased with sodicity up to a maximum ("1300 kN m-2) around the critical sodicity values. This was consistent with values indicated in the literature and was most likely caused by the problems of infiltration, swelling and dispersion. Above the ESP range 15-20, the strength of the surface remained unaffected (" 13 kN m-2) even though sodicity rose to a higher value. These processes could therefore account for the observed poor germination on similar textured soils under irrigation worldwide.
University of Southampton
Kyei-Baffour, Nicholas
cf6e62f5-8631-4423-bf05-be856335e4be
2002
Kyei-Baffour, Nicholas
cf6e62f5-8631-4423-bf05-be856335e4be
Kyei-Baffour, Nicholas
(2002)
A study into the effects of sodicity on the capping of soils.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The hypothesis that the development of sodicity at the soil surface might increase soil strength to give adverse effects on agricultural productivity through impaired germination and poor crop stand simulated this investigation. The study aimed to investigate the link between rising salinity and sodicity at the soil surface from saline irrigation water or capillary rise from groundwater and the development of surface cap strength as well as the effects of leaching and mechanical action on soil surface and profile strength.
Efford soil containing small amounts of expansible clay, mica, known to be prone to capping was deliberately salinised to impose a range of salinities and sodicities at the soil surface with solutions with electrical conductivities, EC's = 1, 4, 8 and 12 dS m-1 and sodium adsorption ratios, SAR's = 0, 2, 4, 6, 8, 12, 20 and 40. It was established that the strength at the surface increased during the actual salinisation process, but significantly increases in strength were almost exclusively related to the rise in sodicity. Further strengthening occurred on leaching, and this was strongly linked to the increased sodicity at the soil surface before leaching. Surface strength was lowest for the non-sodic soil (550 kN m-2) but increased with sodicity up to a maximum ("1300 kN m-2) around the critical sodicity values. This was consistent with values indicated in the literature and was most likely caused by the problems of infiltration, swelling and dispersion. Above the ESP range 15-20, the strength of the surface remained unaffected (" 13 kN m-2) even though sodicity rose to a higher value. These processes could therefore account for the observed poor germination on similar textured soils under irrigation worldwide.
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Published date: 2002
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Local EPrints ID: 464883
URI: http://eprints.soton.ac.uk/id/eprint/464883
PURE UUID: 6d9d11dc-967c-46f8-a2d6-61eeea95b4f1
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Date deposited: 05 Jul 2022 00:07
Last modified: 23 Jul 2022 02:14
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Author:
Nicholas Kyei-Baffour
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