There are many articles based on long-term statistical experiments concerning crop rotation problems in European journals. Subject connected with cereal crop concentration, multi-species monocultures and single species long-term crops are dominant in the articles. Specialized crop rotations while growing potatoes, sugar beets, corn and other species are touched upon less often in these journals.
After the Second World War there was a trend towards specialization in the European economy, which caused the development of this kind of research. It was stimulated by economic factors such as increasing mechanical effectiveness and better work organization, which were both in part due to the increase in mineral fertilization and use of pesticides. Technological and chemical advances were meant to replace the biological functions of developed rotations [ANDREAE 1967].
Within the above subject there were some extreme opinions, which rejected crop rotations as a factor in the regulation of nutritive element circulation as well as hygiene and soil regeneration. In this critical period for scientists representing the ecological basis of plant production in many scientific centers, research concerning simplified crop rotations and monocultures was undertaken. Some of the long-term crops were established earlier and now described as "permanent cultures". [KVCH 1985, NIEWIADOMSKI 1987, ZAWILAK et al. 1990]. The above research is often criticized as without implementative perspectives.
At the same time, well- scheduled and properly-conducted experiments upon plant crop monocultures have educational and practical implementations. An extreme simplification of plant-rotation would allow the description of species and type sensivity to the worst possible type of species, which had grown before in the same location [NIEWIADOMSKI]. Sooner or later in this system of cultivation, harmful biotic factors in soil and plants appear. They are possible to identify and reduce. On the other hand, an increase of non-beneficial ecological processes is accompanied by the creation of a self-defence system in the soil bio-synosis, which creates stability in the crops, but on a lower level than in a crop rotation system.
Learning about above phenomena leads to the development of plant sequencing and concentration in crop rotation theory. Knowing the reaction of species and types to the least effective pre-crop, one may deduct the limit of the scale of their concentration in specialized crop rotation [NIEWIADOMSKI 1987, ZAWILAK et al. 1990]. Plant cultivation in monocultures with anti-stress factor application also allowed the discovery of short-term possibilities of reinforcing factors in the selection of species resistant to "disease and crop rotation insects", organic fertilizer and inter-crop usage pesticide applications in order to lessen the effects of crop rotation [KUPPERS 1972, NIEWIADOMSKI 1980, 1997, KRZYMUSKI 1993, 1992].
In long-term research on crop rotations and monocultures, the production criteria had been dominant until recent years. The change of height and quality of crop, yield and measurable features of plant conditions backed by a correlation regression and variation analysis were discussed. After some time, ecological research such as the chemical characteristics of soil [ZAWILAK et al. 1990, KREJ 1982, ADAMIAK 1987], intensive growth of weeds and their quality [ADAMIAK 1992, ZAWILAK and ADAMIAK 1994a, 1994b], plant diseases [WOJCIECHOWSKA-KOT, CZAJKA and WIWART 1987 , HERMAN1992, KUROWSKI 1992], and finally, parasites living on plant roots [WOLNY 1992] were investigated.
Other works covered ecological production analysis [KREJ 1986, SZWEJKOWSKI 1989]. The economic factor was considered in works showing crop conversion into dry matter, cereal units, oat or fodder units and digestive protein. STUPINCKA-RODZYNKIEWICZ and LEPIARCZYK 1991]. Other authors evaluated work-consumption, intensiveness of production, specialization levels [KRZYMUSKI 1980, PYTKOWSKI et al. 1985].
Various scientific authorities for many years demanded a more complete evaluation of economic plant cultivation in the changing agro-technical conditions along with different crop rotation models like cereal, potatoes, beets etc [NIEWIADOMSKI 1980, 1987]. In 1980s, many studies on the methods of research into cultivated-plant energy requirements consisting of the balance of input and output of accumulated energy [WOJCICKI 1981, ZAREMBA 1986, WIELICKI 1988] were developed and implemented as methods evaluating crop rotation experiments [KU and KRASZOWICZ, 1988, 1991, RZESZUTEK and SOBCZK 1992].