In this Soil Science Australia webinar, Dr Rengasamy challenges traditional ideas about treating soil dispersion based solely on ESP (exchangeable sodium percentage) or SAR (sodium absorption ratio) measures. There are a range of factors the influence dispersion, including salinity, pH, and clay mineralogy and content, the nature of organic molecules and exchangeable potassium and magnesium. He found that dispersion is controlled by the relationship between sodium and the electrolyte strength of the surrounding solution (net dispersive charge). If the net dispersive charge is high, clay particles repel each other and disperse. If it is low or neutralised, particles stay flocculated and soil structure remains stable. To test for dispersive soils, Rengasamy first finds out what the clay dispersion is and then calculates the amounts of amendments e.g. gypsum that will induce flocculation [27:10].#
This is a carefully curated database of important soil resources. The data base is not exhaustive but rather a library of the resources we believe are the most useful for the audience. Each resource has been added after careful consideration against our selection criteria, including but not limited to its scientific validity, accessibility, and readability. The library generally does not include most academic research papers but may include some open-source papers written in accessible English.
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SSA reminds users that these resources are a guide only. Our understanding of soil science is improving continuously so it is important to check the suitability of the information for your purpose with an appropriately qualified professional such as a Registered Soil Professional or a Certified Professional Soil ScientistÂ
