Soil fertility is sometimes defined as its capacity to furnish nutrients to plants, and some other time, in an enlarged concept, as its capacity to furnish nutrients and water. In the first case, soil physical properties have to be taken into consideration as they affect much of the nutrients cycle and availability for crops, while in the second case they are a direct component of soil fertility.
Existing soil maps in Romania at the country level, scales from 1:1,000,00 to 1:200,000 contain information on soil physical properties restricted to texture classes, a specific map referring to this characteristic having been published by Asvadurov.
Most information on physical properties of representative soil profiles are stored in the PROFISOL Database, including some 6000 soil profiles, and referring to texture, bulk density, porosity, water and air characteristics, penetration resistance, etc. Based on this information, a set of pedotransfer functions have been prepared, and they allow estimation of most of these physical properties from input consisting of texture and bulk density (continuous pedotransfer functions), or at least of soil taxa and texture classes (class pedotransfer functions). Using such estimation, an extensive attribute database, attached to the existing digitised Pedo-geoclimatic Microzones map (Florea et al.), has been prepared.
Another set of pedotransfer functions has been prepared, based on information existing on soil maps and in the above mentioned attribute database, estimating existing and risk of various degradation processes, e.g., drought, waterlogging, erosion, compaction, a.o.
Field soil moisture content has been determined to a depth of 3 - 5 m in the 1970' with a frequency of 2 - 3 weeks, during 3 - 5 years, in a score of locations covering the main soil and climate areas of the country. Water regimes according to Rode classification were defined based on these data, either percolative, non-percolative and exsudative regimes being identified in various parts of the country. More recently, a map of the country with soil moisture regimes classified according to the USDA Soil Taxonomy has been published by Munteanu.
Results of research mentioned above made possible to have general information on the state of soil physical characteristics at the country level. Maps for each of these characteristics, as well as for the main degradation processes and risks, have been prepared. Statistics of areas covered by these soil properties and processes, classified by land use, by physiographic and climatic regions, by the main river watersheds, and by administrative districts, are available.
A general discussion based on these data illustrates some specific characteristics of the soil physical properties and regimes in this country, as well as differences, often important, between different areas of the country.
