The aim of this research was to finding methods of calculating the content of water unavailable to plants in the total soil mass based on the water properties of particular grain sizes. Fractions <0.02 mm bind from 90.1 to 98.8% of total water unavailable to plants in soils, and the clay fraction (<0.002 mm) alone binds from 52.1 to 80.1% of this water. Binding water in fractions <0.02 mm significantly depends on the mineralogical composition of fractions. The presence of illite, chlorite or kaolinite causes a decrease of capacity of water unavailable to plants by even 40% in relation to fractions composed of smectites, vermiculites, and humus. Due to high variability of the capacity of water unavailable to plants in particular grain size fractions <0.02 mm resulting from the variable mineralogical composition of this fraction, coefficients allowing to calculate the capacity of water unavailable to plants in soil microcapillaries below 0.2 μm show very high oscillation and could not be applicable.
Brogowski Z., Dobrzañski B., Kocoñ J., 1978. Application of scanning microscopy in studies of the morphology of mechanical fractions of soil. Polish Journal of Soil Science, 1(1): 73-83.
Brogowski Z., Dobrzañski B., Kocoñ J., 1983. The possibility of zeolites occurrence in the soils of Poland. Zeszyty Problemowe Postêpów Nauk Rolniczych, 220: 489-494.
Brogowski Z., Mazurek A., 1981. Differentiation of clay minerals in particular mechanical fractions of soil. Roczniki Gleboznawcze - Soil Science Annual, 32(3): 193-205.
Brogowski Z., Mazurek A. 1986. Mineral composition of fractions <0.02 mm of alluvial soil. Roczniki Gleboznawcze - Soil Science Annual, 37(4): 9-22. (in Polish)
Brogowski Z., Mazurek A. 1990. Mineral composition of soil grains of < 0.02 mm in diameter in brown soil developed from boulder loam. Roczniki Gleboznawcze - Soil Science Annual, 41(1/2): 5-21. (in Polish)
Comegna V., Damiani P., Sommela A., 1998. Use of fractal model for determining soil water retention curves. Geoderma, 85(4): 307-323.
Lipiec J., Stêpniewski W., 1995. Effects of soil compaction and tillage systems on uptake and losses of nutrients. Soil and Tillage Research, 35(1-2): 37-52.
Musierowicz A., Król H. 1962. Correlation between field water capacity and capillary capacity. Roczniki Gleboznawcze - Soil Science Annual, 12: 161-181. (in Polish)
Pranagal J., Lipiec J., and Domżał H., 2005. Changes in pore size distribution and aggregate stability of two soils under long term tillage systems. International Agrophysics, 19(2): 165-174.
Raczuk J. 1987. Some physical properties of brown soil and of its granulometric fractions. Roczniki Gleboznawcze - Soil Science Annual, 38(2): 221-232. (in Polish) Rieu M., Sposito G., 1991. Fractal fragmentation, soil porosity and soil water properties: I. Theory. Soil Science Society of America Journal, 55: 1231-1238.
Trzecki S. 1968. Water retainment forces (pF) by particular mechanical fractions in two different soils. Zeszyty Problemowe Postêpów Nauk Rolniczych, 776: 227-234. (in Polish)
Trzecki S. 1974. Determination of water capacity of soils on the basis of their mechanical composition. Roczniki Gleboznawcze - Soil Science Annual, 25(suppl.): 33-44.
Trzecki S. 1976. Possibility of determination of the moisture of permanent wilting of plants on the basis of maximal higroscopicity and content of clayey particles in mineral soils . Roczniki Gleboznawcze - Soil Science Annual, 27(4): 11-18. (in Polish)
Tyler S.W., Wheateraft S.W., 1992. Fractal scaling of soil particle- size distributions: Analysis and limitations. Science Society of America Journal, 56(2): 362-369.
Waksmundzki A., Staszczuk P., Szymañski E. 1981. Hydratation and dehydratation of clay minerals. Polish Journal of Soil Science, 14(1): 25-35.
Witkowska-Walczak B., Walczak R., Ostrowski J., 2003. Pore size distribution and amount of water available for plants in arable soils of Poland. International Agrophysics, 17(4): 213-217.