[ALLEN R. G., PEREIRA L. S., RAES D., and SMITH M., 1998: Crop evapotranspiration- Guidelines for computing crop water requirements. FAO irrigation and drainage. Pap. No. 56, Rome.]Search in Google Scholar
[AMATO M. and RITCHIE J. T., 2002: Spatial Distribution of Roots and Water Uptake of Maize (Zea mays L.) as Affected by Soil Structure. Crop Science, 42, 773-780.10.2135/cropsci2002.7730]Search in Google Scholar
[ARVIDSSON J., 1999: Nutrient uptake and growth of barley as affected by soil compaction. Plant and Soil, 208, 9-19.10.1023/A:1004484518652]Search in Google Scholar
[BADDELEY A., 2008: Analysing spatial point patterns in R. Workshop on Analysing Spatial point Patterns. CSIRO and University of Western Australia. Workshop Notes, p. 199]Search in Google Scholar
[BALDWIN J. P., TINKER P. B. and NYE P. H., 1972: Uptake of solutes by multiple root system from soil. II. The theoretical effects of root density and pattern on uptake of nutrients from the soil. Plant and Soil, 36, 693-708.10.1007/BF01373517]Search in Google Scholar
[BENNIE A. T. P., 1996: Growth and mechanical impedance. In Plant Roots: The Hidden Half. Eds. Y. WAISEL, A. ESHEL and U. KAFKAFI. Marcel Dekker Inc., New York, USA, pp. 453-470.]Search in Google Scholar
[BINGHAM I. J. and BENGOUGH A. G., 2003: Morphological plasticity of wheat and barley roots in response to spatial variation in soil strength. Plant and Soil, 250, 273-282.10.1023/A:1022891519039]Search in Google Scholar
[BOYADGIEV T., 1994: Soil map of Bulgaria according to the FAO-UNESCO-ISRIC revised legend explanatory notes. Soil Science, Agrochemistry and Ecology, 4-6, 52-56.]Search in Google Scholar
[CHOPART J. L. and SIBAND P., 1999: Development and validation of a model to describe root length density of maize from root counts on soil profiles. Plant and Soil, 214, 61-7410.1023/A:1004658918388]Search in Google Scholar
[DILKOVA R., FILCHEVA E., KERCHEV G., KERCHEVA M., 1998: Humus peculiarities of the virgin surface water-logged soils. In Congres Mondial de Sci. du sol, 16e, Montpellier, France, 20-26 aout 1998. Resumes. Vol. 1, Symp. N 18, p. 378.]Search in Google Scholar
[DROOGERS P., VAN der MEER F. B.W and BOUMA J., 1997: Water accessibility to plant roots in different soil structures occurring in the same soil type. Plant and Soil, 188, 83-91.10.1023/A:1004256113198]Search in Google Scholar
[GEORGIEVA V., MOTEVA M., KAZANDJIEV V., 2007: Impact of Climate Change on Water Supply of Winter Wheat in Bulgaria. Agriculturae Conspectus Scientificus, Vol. 72, No. 1, 39-44.]Search in Google Scholar
[GRIEG SMITH P., 1983: Quantitative Plant Ecology. Univ. of Calif. Press, Berkeley, p. 347.]Search in Google Scholar
[HAKANSSON I. and LIPIEC J., 2000: A review of the usefulness of relative bulk density values in studies of soil structure and compaction. Soil & Tillage Research, 53, 71-85.10.1016/S0167-1987(99)00095-1]Search in Google Scholar
[HIMMELBAUER M. L., NOVÁK V., MAJERČÁK J., 2008: Sensitivity of soil water content profiles in the root zone to extraction functions based on different root morphological parameters. J. Hydrol. Hydromech., 56, 1, 34-44.]Search in Google Scholar
[HORN R., AKKER VAN den J. J. H., ARVIDSSON J. (Eds.), 2000: Subsoil compaction. Distribution, Processes and Consequences, Adv. Geoecology, 32, 462 pp.]Search in Google Scholar
[KOEDJIKOV H. A., 1975: The Root System of Cereal Plants. Publishing House of the Bulgarian Academy of Science, 581 pp.]Search in Google Scholar
[KOLEVA E. and ALEXANDROV V., 2008: Drought in the Bulgarian low regions during the 20th century. Theoretical and Applied Climatology, Vol. 92, No.1-2, 113-120.10.1007/s00704-007-0297-1]Search in Google Scholar
[LABOSKI C. A. M., DOWDY R. H., ALLMARAS A. A. and LAMB J. A., 1998: Soil strength and water content influences on corn distribution in a sandy soil. Plant and Soil, 203, 239-247.10.1023/A:1004391104778]Search in Google Scholar
[LIPIEC J., ARVIDSSON J., MURER E., 2003: Review of modelling crop growth, movement of Chemicals in relation to topsoil and subsoil compaction. Soil & Tillage Research, 73, 15-29.10.1016/S0167-1987(03)00096-5]Search in Google Scholar
[NOVÁK V., 2003: Nutrients uptake by maize roots: vertical distribution of uptake rates during the vegetation period. J. Hydrol. Hydromech., 51, 1, 14-20.]Search in Google Scholar
[PARDO A., AMATO M., CHIARANDA F. Q., 2000: Relationships between soil structure, root distribution and water uptake of chickpea (Cicer arietinum L.). Plant growth and water distribution. European Journal of Agronomy, 13, 39-45.10.1016/S1161-0301(00)00056-3]Search in Google Scholar
[ROGERS A., 1974: Statistical Analysis of Spatial Distributions. Pion Ltd., London.]Search in Google Scholar
[RUSSEL E. W., 1980: Soil conditions and plant growth. Tenth Ed. Longman Group, UK Ltd., 849 pp.]Search in Google Scholar
[SHOPSKI N., ILIEV K., DONEVA E., 1998: Management of surface waterlogged soils fertility by new ameliorative technology and systems. Soil Science, Agrochemistry and Ecology, 33, 2, 35-38.]Search in Google Scholar
[TARDIEU F., 1988a: Analysis of the spatial variability of maize root density I. Effect of wheel compaction on the spatial arrangement of roots. Plant and Soil, 107, 259-266.10.1007/BF02370555]Search in Google Scholar
[TARDIEU F., 1988b: Analysis of the spatial variability of maize root density II. Distances between roots. Plant and Soil, 107, 267-272.10.1007/BF02370556]Search in Google Scholar
[TARDIEU F., BRUCKLER L., and LAFOLIE F., 1992: Root clumping may affect the root water potential and the resistance to soil-root water on the uptake of ions by roots: I. Soil water content near a plane transport. Plant and Soil, 140, 291-301.10.1007/BF00010606]Search in Google Scholar
[VOMOCIL J. A., 1965: Porosity. In: C. A. BLACK (Ed.): Methods of soil analyses. Part 1: Physical and Mineralogical Properties including Statistics of Measurement and Sampling. Agron. Monogr. 9, ASA and SSSA, Madison, WI, USA, pp. 299-314.10.2134/agronmonogr9.1.c21]Search in Google Scholar
[WULFSOHN D., GU Y., WULFSOHN A., MOJLAJ E. G., 1996: Statistical analysis of wheat root growth patterns under conventional and no-tillage systems. Soil & Tillage Research, 38, 1-16.10.1016/0167-1987(96)01019-7]Search in Google Scholar