In Greece, the agricultural land was 66% of the total land in the period from 2000 to 2006, covering a surface of 8.7 million hectares. In relation to the soil used for agriculture, 3.9 million hectares are crops, while 0.49 million hectares are pasture. About 500.000 hectares of arable land are left under fallow each year. 33% of arable land is irrigated.
Table 1.Soil Allocation of Greece (%)
|Land% / Decade||1960-1969||1970-1979||1980-1989||1990-1999||2000-2003|
Source: WDI 2007
Table 2.Categories of Quality of Greek Soil Resources.
|Category||Area 106 ha||Percentage %|
|High quality of soil||2.49||19|
|Average quality of soil||2.33||18|
|Low quality of soil||7.57||57|
|Non uncluded area (urban land, lakes, etc)||0.79||6|
Source: CEC 1992
Furthermore, 56% of arable land is in the lowland areas, while the rest are in mountainous or hilly areas( Paschalidis et.al., 2015)
Greece by two thirds of the surface is predominantlymountainous,characterized by continuous gradients and continuous succession of leanings ( Simonis,1993, 1994) .The soils of our country in their entirety have been created by the dry and hot Mediterranean conditions with the sovereignty of limestone and has established a close relationship with the breast rock. The content of organic matter of the soil is influenced by the thickness of breast rock material, soil texture and inorganic constituents. Thin soils that have emerged from breast rock material which formed by hard rock, produce less growth plants and contain lower percentages organic matter from the fat soils. The thick soils have generally higher content of organic matter,which basically due to the protective action of clay onto the humus, and the formation of the organohumic complex.The dry hot climate of Greece exercises, strong negative effects on the content of organic matter of soil. The temperature is a decisive factor in the level of organic matter in the soil. The influence of temperature resulting from the different way in which the processes of production organic matter and its dissipation, react to temperature increases.(Lal et al.,1998 bazaar, Lal,2001). Generally, the soils of hot areas have lower organic matter from that of the cold ones. The low rate of organic matter of soils in our country is the greatest problem of agriculture. The soils of Macedonia — Thrace, on average, containing 1.15% organic matter ,which continues to be reduced with speed 0.8% approximately every year accompanied by a fall in the chemical, physical and biological fertility of the soil with ramifications which is in the short and long term, deterministic for agricultural development of our country. ( Koukoulakis, 2005 ).
In the present work possesses regarding the results of analyzes soil samples, resulting mainly from the regions of Peloponnese, Sterea Hellas and Attica. Gives a picture of the basic soil properties of the above areas and particularly in cultivation areas of olives, grapevine and citrus fruits.
Materials and methods
From 1991 in soil science Institute of Athens began a systematic recording and collection of information from the analyzes soil samples, plant tissues (Theodorou et.al,1995, 1999).The characteristic properties of the soil are as follows:The soil texture, pH, the concentration of CaCO3, organic matter, nitrogen, phosphorus and potassium.The soil texture analysis was done by the method of Bouyoucos , the pH measured in suspension soil : water 1:1, for the measurement of CaCO3used the method Bernard, the method of ammonium acetate was applied for the determination of the C.E.C. meq/100g and the exchangeable cations, for the determination of organic matter used the method of digestion (Walkley- Black). All the laboratory analysis took place according to the methods which are described in the book of part 2 (Page, 1982).
Results and discussion
- Soil texture
From the whole of 2.040 representative samples studied, 63 % are medium to heavy soil texture recommendation and the 17% to 20 % heavy soil texture recommendation. The samples were analyzed by olive and vines culturesshow differentiation of soil texture of the above general image, while in citrus cultures 64.3% of surface soil (0-30cm) and 72 % of the subsoil (30-60 cm) are medium to heavy soil texture recommendation. Unlike the overall picture showing the zones olive and vine cultures, in citrus fruits 35.7 of surface soil(0-30cm) and 28 % of the subsoil are medium to light soils. Thus, on the entire samples dominate medium to heavy soils.The soils are productive, with particular problems in processing, the irrigation and rational fertlilization.
2.The reaction of the soil (pH)
Generally, the reaction of the soil with a pH, between 6.0-7.3 may be considered the best for cultivated land and between 5.5- 7.5 % for the meadows. The diagrams 1 and 2 show comparatively the percentage breakdown of values of pH at all representative samples analyzed. The soil samples from vine plantations and citrus fruits show on the analyses the same proportions pH values, while the samples from olive cultures in percentage 40 % gave acid reaction. The diagrams show that the main areas sampling dominate the alkaline soils (72 % and 64 %).
Table 3.Characterization of soil according to the pH.
|4.5-6.0||Very strong acidic to acidic soils|
|6.1-6.5||Slightly acidic soils|
|7.4-7.8||Slightly alkaline soils|
|7.9-8.4||Moderately alkaline soils|
Figure 1. Soil allocation surface (0-30 cm) in relation to the pH.
Figure 2.Soil allocationof subsoil (30-60 cm)in relation to the pH.
3.Content of soil calcium carbonate
The soils of Greece, as a general rule, come from of breast rock material, rich in calcium and developed in conditions which are unfavorable in the intense rinsing of calcium carbonate throughout the profile so as to dominate in the soils with alkaline reaction. Tables 3 and 4 give a general picture of the whole of the analyses of representative soil samples and classification of these soils on the basis of the content of calcium carbonate.
Table 3.Allocation of land according to their content calcium carbonate, in sampling areas.
|Calcium carbonate content (%)||Allocation of surface soil samples (%)||
Allocation of subsoil samples (%)
Table 4. Soil allocation according to their content of calcium carbonate samples from olive groves, vineyards and citrus.
Soil category according to their content calcium carbonate
|Olive groves||Vineyards and||
From these tables generally appear to dominate soils rich in calcium carbonate (CaCO3). In olive groves dominate the poor and rich in calcium carbonate soils. In vineyards represented all categories containing calcium carbonate, while fault occurs in soils with CaCO3 above 40%. It should be noted that soils with a high content of calcium carbonate is undesirable because it reduces the percentage of clay which along with organic matter are the active ingredients of the soil (Cations ExchangeCapacity), (figures 3 and 4).
Figure 3.Content of soil calcium carbonate (CaCO3%) in soil types
Figure 4.C.E.C.in soil types.
The soils with a high quantity of calcium carbonate is problematic because it is closely connected with high pH and active calcium carbonate, with commitment phosphorus and steel with relatively low capacity cation exchange.
- Soil organic matter
Soils are the largest carbon warehouse. The soil contains organic matter, an important energy source. The energy potential of the organic matter is essentially due to the photosynthesis process. Commitment CO2 through photosynthesis, is the main source of organic carbon in soils. The energy balance of the Greek soils with ratio of input: output 1:1.45, reflecting the expanded level of mechanization and general development of Greek agriculture which is comparable with those of other countries balances (Koukoulakis, 1990). The percentages of organic matter vary depending on climate, soil type, the content of calcium carbonate and crop management system.The indirect effect of organic matter on soil fertility improvement based on the chemical and physical properties. Soils regularly fertilized with organic fertilizers have better physical properties and feeding ability of the plants. In whole of the analyzed soil samples in 75.3% of surface (0-30cm) and 91.2% of subsoil samples (30-60 cm) is poor to very poor in organic matter (<1% to 2%) . Unilateral and excessive use of industrial fertilizers and general abandonment adding the soil organic material, a gradual but steady, irreparably damaging the productivity of the soil quality of the natural environment. Climate change, with increasing temperature and decreasing rainfall in our region assists in the rapid decrease in the level of organic matter.
The soils of Greece as a whole, were created in the hot and dry Mediterranean conditions. The soil sampling areas are mostly medium to heavyand are characterized as productive soils. They are mostly moderately alkaline, and a small proportion of strongly acidic, moderate to high in calcium carbonate. Soils classified poor in organic matter. The hot and dry climate of Greece carries strong negative effects on the content of soil organic matter.The temperature is a determining factor in the level of organic matter in the soil. Organic matter is still falling at about 0.8% annually, accompanied by a drop of the chemical, physical and biological fertility of the soil. The problem of enrichment of soils with organic matter becomes more topical. Should apply basic rational management practices of organic matter through application of appropriate legume crop rotation systems and grasses, the use of organic humic fertilizers, which are techniques for improving the level of organic matter and hence soil fertility. It is considered necessary to take anti-corrosion measures to reduce organic matter losses.
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