Relationship between soil organic matter lability and liming requirement in acid sandy-loam Cambisols
2007
Kolar, L.,Jihoceska Univ., Ceske Budejovice (Czech Republic). Zemedelska Fakulta | Klimes, F.,Jihoceska Univ., Ceske Budejovice (Czech Republic). Zemedelska Fakulta | Gergel, J.,Jihoceska Univ., Ceske Budejovice (Czech Republic). Zemedelska Fakulta | Svecova, M.,Jihoceska Univ., Ceske Budejovice (Czech Republic). Zemedelska Fakulta
The presence of organic matter and its microbial oxidation to CO2 considerably influences soil requirements for calcareous compounds as well as the lime dose to reduce soil acidity resulting from the impact of balanced buffering CO2-HCO3- system. Topsoil samples were taken from acid sandy-loam Cambisols in three different localities and analysed. If we take into consideration that the content of water per hectare of topsoil (total weight of 6,000,000 kg) is 1,200,000 L, soil water is able to use up to 220 kg CaCO3/ha for the fixation of free surplus CO2 to the value of equilibrium CO2, at zero elution! This process leads to 300-400 kg water-soluble Ca(HCO3)2. Of course, the ion exchange and the buffering system of the soil have further requirements for Ca compounds. Consequently, the doses of calcareous compounds cannot be calculated only on the basis of soil acidity and Ca needs of plants. Therefore, during the years 1986-2004, we studied changes in the stability of soil organic matter in nine watersheds of Sumava (Czech Republic) and their relationship with variations in calcium carbonate equilibriums. The loss of the least stable fraction of soil organic matter and the associated loss of the microbial activity were found to lead to a decrease in Langelier saturation index in the waters, hence to a reduction in water corrosivity against CaCO3, and so to a smaller need of liming to establish the calcium carbonate equilibrium in soil solutions, even though exchange and active acidity of soil increased.
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