It was found that nonequilibrium crystallization of ice from solution leads to decrease of hydrogen index (pH) of frozen part of soil suspension /1/. It was shown /2/ that pH in natural frozen soil decreases on the mounds and increases on the hollows of soil surface.It seems realistic to expect that local soil acidity will be changed by creating of ridged soil surface.It is known that the ridging of soil surface on a field is used as effective method of temperature control during freezing-thawing.As it was pointed out earlier /3/ seasonally changes of soil temperature depend on size,type of ridge and distance between neighbour ridges. In this work we used a ridge factor to control the changes both acidity and water content in soil during freezing-thawing . A set experiments were run with dernopodzolic loam soil (pH=5.0). Disturbed soil samples were taken in the late fall before freezing and in the early spring at once after outset of thawing. We have found that the maximum decrease of acidity and maximum increase of water content followed by maximum decrease of temperature at the top of ridge. We can conclude from this experiments that it is possible to create numerical model of the freezing - thawing affectation on acidity changes on soils formed on the definite parent materials.
References
I.B. Uskov Agrophysical Research Institute 195220 Grazhdansky Prosp.14, St. Petersburg, Russia Tel.: (812) 535-52-13 Fax: (812) 535-52-20 or 534-19-00 E-mail: ivl@agrophys.spb.su E.M. Savelieva 191186 B.Koniushennaia 5, apt.20, St. Petersburg, Russia Tel.: (812) 314-52-40 L.V. Kozyreva 195220 Grazhdansky Prosp. 14, St. Petersburg,Russia Tel.: (812) 534-46-54