Plant production is based on the interaction of soil, work and capital. The numerical ratio in which they occur may be variable. The optimal method of management is the one, which not only completes the main goal, but also actively uses a factor, which occurs in its minimum. In developed countries, work occurs in the minimum because of its high cost. Under such conditions, simplification, production specialization and replacement of the work by mechanical and chemical means is economically justified [KU, HARASIM and KRASOWICZ 1988, KUS, KPASOWICZ and HARASIM 1988]. The employment indicator in Polish agriculture equals 27%. Because of high unemployment, cities can not absorb rural inhabitants, thus the establishment of rural-based industries producing non- agricultural goods is recommended. Owing to the relatively stable soil conditions, the main influence on agricultural production in Poland is work and capital. That is why some of the conventional farms are converting themselves into integrated and partly ecological farms [NIEWIADOMSKI 1992, 1993, 1995].
Not only high crop yields and economic benefits, but more importantly, soil care and fertility are expected from plant production systems. It is commonly known that the agricultural usage of soil degrades the soil [RYSZKOWSKI 1988]. The usage of crop rotation is one of the ways to prevent the above phenomenon [WITOCHOWSKI 1957, KNNECKE 1974, NIEWIADOMSKI 1980, 1994, KVCH 1985, and VRKO 1992]. Crop rotation is a controlled plant sequence, which stabilizes an agro-system's equilibrium.
However, because of the need for simplified usage it can not be multi-directional. For this reason, a biological peak level of inter-crop participation is examined.
The above inter-crops are crops, which are important in economics like cereal, potatoes, sugar beets, and corn and other. According to NIEWIADOMSKI (1980, 1987, 1988, 1993) the studies into monocultures along with anti-stress factor usage are very useful in obtaining the maximum degree of specialization.
In order to evaluate plant crops in rotations and monocultures, production, ecological and economic criteria are used. The implementation of a few indicators is necessary because each of the above has different importance depending on the kind of crop and its future implementation [KRZYMUSKI 1992]. The above indicators may be the following: Productivity is represented by different measurements: the humus and nutrient content of the soil, weed development, the concentration of parasites, bacteria and pathogenic fungi and, finally, work input, energy input and balance of costs [KREJ 1986, SZWEJKOWSKI 1999, STRAIL, 1990, NIEWIADOMSKI 1993,1995].
Not so long ago, the production aspect was dominant. The results of experiments were evaluated using natural crops or converted measurements, such as cereal units, dry matter, oat or feed units, digestive protein and others. A newer criterion for crop evaluation is energy units [ZIOECKA et al. 19791. The usage of natural units in crop evaluation is still used if, for one or a group of related species for example, cereals with a view to their reaction to various agro-technical factors. The examples of the above works backed by statistical analysis are works capitalizing on long-term experiments [ADAMIAK 1987, DZIENIA 1978, FORDOSKI et al. 1993, KREJ 1987, NIEWIADOMSKI et al. 1988, ZAWILAK 1983]. In evaluating the productivity of crops cultivated in the crop represented by different species giving different crops (grain, seeds, bulbs, leaves), convertible indicators allowing their comparison are necessary.
The biological criteria concern the existence of negative biotic factor scale negatively influencing crops in the way of plant diseases [HERMAN 1992, KUROWSKI 1992],
Parasites [WOLNY 1992] and weeds [ADAMIAK 1992, GAWROSKA-KULESZA et al. 1988, VARGA et al. 1994].
The effectiveness comparison of different species cultivated in monocultures and in long-term crop rotations were presented by the following authors: GONET and STADEJEK (1991), KREJ (1987, 1992) GAWROSKA-KULESZA et al. ( 1988), URBANOWSKI (1991), ZAWILAK and et al. (1988), and also as monographies - ZAWILAK and SADOWSKI (1992), ZAWILAK AND TYBURSKI (1992).