One of the most important natural resource of Hungary is soil. The most important feature of the soil, as a three-phase polydisperse system, is fertility, which is related to water- and nutrients, as well as thermal energy storage capacity of soils, the dampening and buffering capacity of the various physical, chemical effects, with nutrient-service activities that associated with microbial activity.
The functions of soils (Várallyay, 1992) are summarized as follows:
• Conditionally renewable natural resource, whose quality (functionality) not decreases necessarily and inevitably by the usage (primer biomass production), but the maintenance, preservation requires constant awareness activities, of which the most important elements are the reasonable land use, agricultural techniques and melioration;
• Ensures territory for microorganism activity is soil, production site for natural vegetation, cultivated crops, by integrating and transforming the impact of the other natural resources (solar radiation, atmosphere, surface and underground water storage capacity, biological resources);
• Elementary medium of primer plant biomass production, which is more or less ensures the soil-ecological conditions of plants, especially water- and nutrient supply, thus the primary nutrient source of the biosphere;
• Environmental element that is able to store heat, water and plant nutrients; buffer medium of stress effects that reach the soils for the impact of natural and human activities, it is capable to mitigate, moderate the adverse effects of them - within certain limits.
• Huge filter system of the nature that is able to protect deeper layers and underground water resources from contamination that reaches the surface.
It follows from the above mentioned that soil attends many functions, from which one of the most important is its fertility, but no means the only one. The obstacles of productivity are the following (Várallyay, 1985):
• High sand content (low organic and colloidal minerals content); Consequences: low total available soil water, drought sensibility, low buffering capacity, acidification sensitivity in case of non-calcareous soils, poor nutrient supply ability;
• Highly acidic pH soils; consequences: Al-toxicity, nutrient fixation and immobilization, low microbial activity;
• Negative consequences of salinisation: strong alkalinity, extreme water management, inland water hazard, little usable water resources, negative nutrient state;
• Salinisation in deeper layers of the soil; high clay content; negative consequences: extreme water management, inland water hazard and drought sensibility, little usable water resources, adverse microbial activity and nutrient state;
• soil degradation by permanent saturation, periodic surface water cover, water erosion and deflation, of which
Reasons of spatial variability in agriculture
In the latter period, five major programs related to the formulation of agricultural tasks of the above mentioned area in co-ordination of academic István Láng and the MTA:
• Agro-ecological potential of the Hungarian agriculture (Láng et al., 1983; Várallyay et al., 1985)
• Alternative biomass utilization for different purposes (1981-1983)
• Adaptive agriculture (1988-1992) (Láng and Csete, 1992)
• Agro - Quality 21 (1996-1998)
• Agro-21 (1993-1995) (Agro-21, 1995)
The above researches have highlighted the key factors, which are capable to ensure long-term the multi-purpose use of soils. In European context, land use of Hungary will be characterized long term by the very large proportion of cultivated soils according to the area of the country and also determinative that extent of those areas, which are affected by soil productivity inhibitory factors, is more than 50% within the cultivated soils, as it is shown in Table 2 (Szabolcs and Várallyay, 1978).
The formation of soils, as in other parts of the Earth, is influenced by the geological, climatic, topographical, biological and human factors, as well as the age of soils. In Hungary, due to the basin character, these effects mixed especially strongly. It is worthy to note that after studying tabular data, map, which describes spatiality, and the individual inhibitory factors that are next to each other (Figure 2) point at how much better for example the complex soil conditions of the Great Plain.
The descriptive tabular data analyze effectively the quantitative relationships and overall point out the fact that high detailed knowledge of the production site is particularly important in our country, correlate to other parts of Europe, but it have a number of obstacles, for which it is pointed at several points of the book. One major disadvantage of tabular data (table 3., 4., 5.) is that they are unable to give back accurately the spatial (concerning to the examined area) overlapping effects of the examined impacts and their timeliness, but reflect accordingly the quantitative relations of the main active agents.
Reasons of spatial variability in agriculture
Based on the tables (No. 3-5), a preliminary assessment can be made to the spatial extent of heterogeneity. By the analysis of soil forming factors, we cannot ignore the impact of human activities on soil either. This effect is particularly intense in the last few hundred years. This human activity causes the promotion of soil fertility on the one hand; on the other hand, it causes the deterioration of soil fertility in certain areas. All the soil forming factors listed in table 7 developed their effects together in the Carpathian Basin, and their interaction limited the appearance form, physical, chemical and biological properties of the given soil.
Reasons of spatial variability in agriculture
The soil processes constitute different contrast pairs, which are in dynamic balance in space and time. These equilibrium processes may shift to one or the other direction of the process, they may intensify, change periodically in time, may have longer or shorter periodic impact. Their impact is periodic or permanent in any spatial unit of the three-dimensional soil space. The most important process pairs are listed in Table 8, by Stefanovits et al. (1999).
The basic factors affecting soil formation, and the ever-changing soil processes in the Carpathian Basin resulted much more complex spatial and temporal heterogeneity to the European average in the formation of the similar soil formations, which resulted three-dimensional mosaic soil variability in the topsoils of Hungary.
This mosaic location is clearly identified nowadays on small landscape level, and in certain parts, within the small landscapes as well in part landscape units. The Hungarian soil sciences specialty is still debtor with the development of the high-precision, high-detailed digital substance soil information system. One of the biggest tasks of the near future is the professional, effective creation of this soil information system.