On the basis of the conducted research and analyses, in the years 1972, 1992, and 2010, changes of the chosen chemical properties of soil were evaluated, where five cereal species were grown in two environmentally correct crop rotations and in single-species monocultures. In 1972, set as the starting year for change evaluation, the content of organic carbon and assimilable phosphorus were usually higher in the soil of cereals grown in crop rotation than in monoculture. Soil pH and the content of other assimilable microelement forms did not demonstrate this type of one-way tendencies. Depending on the cereal species, their higher content was noted in either crop rotation soil or in monoculture. In 1992, after 20 years of manure-free plant cultivation, a decrease in organic carbon content was found, usually higher in monocultures than crop rotations. Assimilable calcium content decreased, whereas soil pH and the contents of other assimilable forms of macroelements increased. Manure fertilization, applied from 1992, attributed to the increase in the content of organic carbon in the soil. After 18 years of its application, organic carbon content almost on all the plots was higher than in the initial year 1972. However, soil pH decreased, as did, with few exceptions, calcium content. The content of other macroelements, depending on the cereal species and cultivation post, has increased or decreased.

The cost-effectiveness of four production systems of a short-straw form of winter triticale (cv. Alekto) with different levels of nitrogen fertilization and fungicide treatment was determined. Based on the current prices of means of production, the total cost of winter triticale production was estimated at PLN 2200-2600, and direct costs accounted for 60-65% of total costs. Regardless of the applied production technology, the predominant cost items were mineral fertilizers (30-39%), followed by the costs of tractor and machine operation (approximately 26-30%), crop protection agents (approximately 11-19%) and labor (approximately 3%). The highest productivity (grain yield per 1 ha) and cost-effectiveness (income per 1 ha, unit production cost, profitability ratio) were noted in a production system where short-straw winter triticale was fertilized with nitrogen at 120 kg·ha^-1 N in two equal splits (BBCH 27 and 32) and subjected to two fungicide treatments (BBCH 31 and 39).

During the growth of underplant and cover crop interactions occur, the patterns and mechanisms of which are not totally known, particularly within the changeability of ecological factors. Joint use of environmental resources may modify the uptake of nutrients from the bedding and their accumulation in the particular plant organs. The aim of the study was the determination of the effect of interactions between spring barley and red clover on phosphorus content in their organs against diversified water provision. In a pot experiment (three cycles), the study factors were: (1) plant sowing type (growth of each species in pure and mixed sowing), and (2) plant provision with water (dose that satisfies plant requirements and one lowered by 50%). Mixture was composed according to the additive pattern. Phosphorus content was marked in plant material uptaken at five stages set by the developmental rhythm of barley in pure sowing in the conditions of more favourable water supply. Sowing type had no effect on phosphorus content in spring barley organs but mixed sowing resulted in the accumulation of a higher amount of phosphorus in the roots at the straw-shooting stage, and a lower amount in the shoots and spikes at the end of growth. In red clover, mixed sowing lowered phosphorus content in the roots at cereal maturity stage. Competition on the part of barley inhibited the uptake and accumulation of phosphorus by red clover. Water supply did not diversify phosphorus content in the organs of spring barley and red clover but water deficit almost throughout the entire period of growth limited phosphorus uptake by both species. Competition on the part of barley was for red clover a stronger factor that impeded phosphorus accumulation in plant organs than water deficit. Water stress did not intensify further the negative effect of competition.

Investigations were carried out in patches of Molinietum caeruleae meadows dominated by small meadow species (patch I), characterised by prevailing large-tussock grasses (patch II), and overgrown by willow shrubs and bordered by trees (patch III). In each patch, 15 circular gaps with a radius measuring 30 cm were artificially created by the removal of the plant canopy and litter layer. Subsequently, each gap was divided into a central part, with a radius of 20 cm, and a peripheral part. Light intensity and soil temperature were greater in the central parts of these openings than in their peripheries, while ground humidity presented the inverse tendency. Despite heterogenous environmental conditions in the gaps, the total numbers of species/seedlings noted in their central and peripheral parts did not differ significantly. The majority of taxa recruited similarly over the entire surface of openings; a much lower number of species colonized primarily the central parts of gaps; the lowest number of taxa appeared at the edges of openings. In the light of these investigations, it may be assumed that heterogenous microsite conditions in openings enable the recruitment of taxa with various germination requirements and contribute to the maintenance of species diversity.

The aim of the study was evaluation of the effect of various sowing density and the course of weather conditions in the growing season on the yield and structural yield components of chosen brownand yellow-husked genotypes (cultivars and strains) of common oats. The two-factor field experiment was carried out in the years 2007-2010 at the Institute of Crop Production and Cultivation of Małopolska Plant Growing Company in Polanowice near Krakow. The first experimental factor were 6 cultivars/strains of common oats: 3 cultivars/strains of brown-husked cultivars (Gniady, CHD 2875/01, CHD 2833/02) and 3 yellow-husked cultivars (Bohun, Deresz and Cwał). The second factor were 3 sowing densities: 300, 400 and 500 germinating grains·m^-2. The brown-husked (5.90 Mg·ha^-1) and yellow-husked (6.13 Mg·ha^-1) genotypes of oats which were compared in the study, did not differ significantly in the grain yield quantity, however, significant differences were observed between particular strains and cultivars (Gniady, CHD 2875/01, CHD 2833/02, Bohun, Deresz and Cwał) both in grain yields and in the number of grains developed per panicle, as well as in 1000 grain weight. The average oat yield obtained in the experiment was 5.6-6.4 Mg·ha^-1, while the highest one was obtained from the brown-husked strain CHD 2833/02. Diversified sowing density had no effect on the grain yield quantity, however it significantly varied structural components of the yield. Increase in the density was directly proportional to the number of panicles developed per unit of area. The studied experimental factors had a significant effect on grain plumpness in the studied material. The highest yielding cultivars and strains (CHD 2833/02, Bohun, Deresz) were characterized by a higher proportion of small grains (<2.2 mm), and by a lower content of larger grains. The course of weather conditions in the years of research significantly diversified yield quantity, structural yield components and grain proportion of particular fractions. In 2008, under conditions favorable for growth and development of oat plants, the proportion of grains from fraction 2.5-2.7 mm was higher than in other years of research.

Legume-cereal mixtures are a valuable source of protein for animals. Mixtures of lupine with oat are recommended for cultivation in weaker soils. This paper presents the result of the study from 2009-2011 aimed to estimate the effect of composition and harvest time of mixtures of blue lupine with oat on the content and yield of total protein in green matter. Two factors were studied in the experiment: I) mixture composition: blue lupine – pure sowing, oat – pure sowing, blue lupine 75% + oat 25%, blue lupine 50% + oat 50%, blue lupine 25% + oat 75%, II) harvest time: flowering phase of blue lupine, the flat green pod phase of blue lupine. During harvest of mixtures, mean samples of fresh matter were collected from each plot, in order to perform chemical analyses. The content of dry matter and total protein in the collected plant material was determined and the total protein yield was calculated. The obtained results of the study allow us to state that the dry matter yield of mixtures of blue lupine with oat harvested in the phase of flat green pod was significantly higher than the dry matter yield of mixtures of blue lupine with oat harvested in the flowering phase of blue lupine. Mixtures harvested in the flowering phase of blue lupine contained more total protein than mixtures harvested in the phase of flat green pod of blue lupine. Green forage from blue lupine harvested in the flowering phase was characterized by the highest content of total protein. Total protein yield from mixtures of blue lupine with oat obtained in the flat green pod phase of blue lupine was significantly higher than the total protein yield obtained from mixtures harvested in the flowering phase of blue lupine. The highest total protein yield was provided by a mixture of blue lupine with oat with 50% of both components harvested in the phase of flat green pod of blue lupine. Mixture of blue lupine with oat with 50% of both components harvested in the flat green pod phase of blue lupine provided the highest dry matter yield with the highest amount of total protein.

Based on a 3-year pot experiment carried out according to an additive design, the effect of competitive effect of red clover and water deficit was studied on morphological traits of spring barley (length of the root, shoot and ear, total and productive tillering, leaf number and grain number per ear). The experimental factors included: level of substrate moisture and sowing method. Two levels of moisture were used: the one which met plants’ requirements, and one reduced by 50%. The plants were sown in a pure stand (18 plants of spring barley per pot) and in a mixed stand (18 plants of spring barley with 8 plants of red clover per pot). Biometric measurements were conducted in five development stages determined by the growth rhythm of barley in pure sowing with a higher water dose, i.e. in the stages of (BBCH scale): leaf formation (10-13), tillering (22-25), shooting (33-37), ear formation (52-55) and maturation (87-91). It was indicated that common cultivation of spring barley with red clover had no effect on the analyzed morphological traits of this cereal throughout the whole growing season. On the other hand, water deficit in the substrate resulted in a reduction in cereal growth in tillering-maturation stages, in the formation of a lower number of leaves (tillering-shooting) and in a poorer total and productive tillering. Water stress also caused formation of shorter ears with a lower number of grains filling them. Competitive effect of red clover amplified with water deficit resulted in the reduction in the number of productive shoots in barley. No effect of experimental factors was found on the root length in the initial growth stages (leaf formation-tillering).