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Use of calcareous compounds to correct soil characteristics

I would like to obtain some information about the use of calcareous compounds to correct soil characteristics. I would appreciate some answer as well as suggestions of useful sites to obtain more information.

Efraín Barbery

e.barbery@lettera.net

Answer

Crushed or ground limestone (CaCO3 with some impurities) is the most widely used calcareous material to correct soil characteristics in agriculture, forestry and lakes in Scandinavia. Dolomite (mixture of CaCO3 and MgCO3) is used in case magnesium (Mg) content in soil is low and needs to be corrected simultanously with liming.

Burning limestone results in CaO, which is the same as "burnt lime" or "quick lime". It is often used in gardening, where its higher price my be compensated by less voluminous and faster reaction. CaO plus water will result in "hydrated lime" or "slaked lime", Ca(OH)2. Adding CaO or Ca(OH)2 in excess to moist soil will rapidly result in CaCO3. This is done to improve soil structure in some cases, e.g. over drainage pipes. CaCO3, CaO and Ca(OH)2 will all increase soil pH, most rapidly with CaO and a little slower with CaCO3. The speed of the latter is dependent on the size of the granules: the finer the powder the faster the reaction.

The objectives of using liming agents is to increase soil solution pH or lake water pH in order to counteract toxic levels of aluminium (Al) and manganese. Vulcanic ash soils have a high content of soluble Al in spite of a pH around 7. Gypsum (CaSO4) is sometimes applied to vulcanic ash soils in order to reduce toxic levels of Al by formation of aluminium sulphates without increasing soil solution pH.

A short review about liming in Sweden can be found in Hylander, L.D. (1995) "Diverging liming effects: a causal study". It can be ordered for a small fee from Swedish University of Agricultural Sciences, Department of Soil Sciences. Att. Pia Edfeldt.

Agricultural books about plant production and horticultural books also address the handling of liming.

Lars Hylander

Lars.Hylander@ebc.uu.se
Evolutionary Biology Centre
Department of Limnology
Uppsala University
Sweden