Year: 1993
Type: book-chapter
Abstract: Aggregate stability, which influences soil\nresponse to raindrop impact and other\nerosive forces, is affected by freezing. We\nhypothesized that lime or gypsum added\nat agriculturally feasible rates may act\nas bonding agents to mitigate the effects\nof freezing on the stability of aggregates\nfrom different soils. Thus, the objectives\nof the laboratory study were to\ndetermine the effects of freeze-thaw cycles,\nwater content at freezing, and lime\nand gypsum additions on the aggregate\nstability of six soils differing in texture,\nmineralogy, and organic matter. To all\nsamples but the control, either CaCO3\nor CaSO4 - 2H2O was added at a rate\nof either 0.2 or 1.0% by weight of oven-dry\nsoil. Field-moist aggregates were\nvapor-wetted to either a low water content\n(5-10% w/w) or a high water content\n(25-30%), then frozen and thawed\neither 0, 1, or 3 times in brass cylinders.\nAfter thawing, they were vapor-wetted\nto 0.30 g g-1 and their stability\nwas characterized by wet sieving. For all\nsoils, aggregate stability decreased significantly\nwith increasing water content\nat freezing. When averaged over bonding\nagents and addition rates, soils commonly \n\nincreased in stability, at times\nsignificantly, after one freeze-thaw cycle.\nSoils with clay contents of 20% or\nmore and organic matter contents over\n3% were the most stable after freezing.\nWhen averaged over soils and freeze\nthaw cycles, aggregate stability was not\naffected by bonding agents at low water\ncontents. At high water contents,\nhowever, stability increased significantly\n(P<0.05) when CaSO4 at a rate of 0.2%\nwas added. Though the differences from\nagent to agent at high water contents\nwere not significant at the 0.05 level,\nCaSO4 appeared to increase aggregate\nstability more than CaCO3 . Surprisingly,\nstability tended to be greater at\nthe lower rather than higher application\nrates. In conclusion, aggregate stability\n1. decreased with increasing water\ncontent at freezing, and\n2. increased after CaSO4-amended soil\nsamples at high water contents were\nfrozen.
Authors: G.A. Lehrsch, R.E. Sojka, P.M. Jolley
Language: English
Subfield: Soil Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W2122442801