Impact of monovalent cations on soil structure. Part II. Results of two Swiss soils
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Faculty of Agriculture, Department of Soil Science, Ferdowsi University of Mashhad, Azadi Square, Mashhad, 917751163 Iran
Agroscope, Department of Agroecology and Environment, Zurich, Reckenholzstrasse 191, CH-8046, Switzerland
Department of Soil and Environment, Swedish University of Agricultural Sciences, Box 7014, SE-75007 Uppsala, Sweden
Publication date: 2018-02-03
Int. Agrophys. 2018, 32(1): 69–80
In this study, we investigated the impact of adding solutions with different potassium and sodium concentrations on dispersible clay, water retention characteristics, air permeability, and soil shrinkage behaviour using two agricultural soils from Switzerland with different clay content but similar organic carbon to clay ratio. Three different solutions (including only Na, only K, and the combination of both) were added to soil samples at three different cation ratio of soil structural stability levels, and the soil samples were incubated for one month. Our findings showed that the amount of readily dispersible clay increased with increasing Na concentrations and with increasing cation ratio of soil structural stability. The treatment with the maximum Na concentration resulted in the highest water retention and in the lowest shrinkage capacity. This was was associated with high amounts of readily dispersible clay. Air permeability generally increased during incubation due to moderate wetting and drying cycles, but the increase was negatively correlated with readily dispersible clay. Readily dispersible clay decreased with increasing K, while readily dispersible clay increased with increasing K in Iranian soil (Part I of our study). This can be attributed to the different clay mineralogy of the studied soils (muscovite in Part I and illite in Part II).