Strict, three-year-long field experiment was performed on degraded Phaeozems, IIIb soil valuation class, with pH ranging from 6.5 to 7.1, of high richness in phosphorus and potassium, medium in magnesium, and low in sulphur. The experiment was carried out in a split-block design with two factors in four repetitions. The aim of the study was to evaluate the effect of various doses of nitrogen (0, 60, 120, and 180 kg· ha^-1) and sulphur (0, 20, and 60 kg· ha^-1), taking into account their different application methods (in-soil and as foliar fertiliser), on the yield components of spring rapeseed cultivar Star. Fertilisation only with nitrogen significantly increased the values of all the studied components, while the sulphur-only fertilisation increased the number of seeds in siliques, as well as the mass of 1000 grains. The number of seeds per silique in none of the research years was significantly affected by the interaction between nitrogen and sulphur. As far as other characteristics are concerned, considering sulphur alongside nitrogen fertilisation, in general, resulted in a significant increase in their values, in comparison with the control plants.

Changes in the floristic composition of meadows and pastures may provide information on the human impact on the habitat conditions and intensity of land use. The aim of the study was to present the floristic diversity of the Lolio-Cynosuretum association and its relation with the habitat conditions evaluated using the phytoindication method with Ellenberg indicators. The study was conducted in five river valleys in the years 1999-2012. For the analysis, 100 relevés were selected, which were subject to floristic, habitat (phytoindication), and statistical analysis. In the Lolio-Cynosuretum phytocoenoses, the total number of 178 taxa of vascular plants from 33 families was recorded. It was demonstrated that the differentiation in the floristic composition of Lolio-Cynosuretum phytocoenoses remains in relation with the habitat conditions, which may be evaluated basing on the ecological preferences of plant species that form the taxa. The species were established as differential for the lower units, that is four subassociations and eight variants.

Due to progress of ecological farming the breeders and farmers need to know how to store ecological cereal seed material. Investigations on the seed storage value of ecological and conventional seeds were performed on naked and hulled oat during 5 years of storage in a granary and long-term store. There were analysed germination capacity, mean germination time, vigour by the growth test according to ISTA method and response to drought stress. It was found that germination capacity and vigour were lowest for the organic seeds of cv. Polar stored in a granary. In the hulled cv. Krezus degradation process was delayed. In case of long-term storage, seed value was retained irrespective of the cultivar or method of cultivation. The highest response to drought stress occurred in organic seeds of cv. Polar taken from a granary. The response to drought stress of the hulled cv. Krezus was lower irrespective of method of cultivation.

The aim of the study was to evaluate the use of agri-environment schemes in the years 2004-2006 and 2007-2013 by farmers south-eastern Poland. In this region are more implemented these packages sciences, which are less onerous. Most of the agri-environmental programs implemented by farmers, puts great emphasis on the conservation and preservation of the rural landscape. Agri-environmental program increased environmental awareness among farmers who implement it and helps to inhibit the development of intensive agriculture. Simplification of the documentation related to the agri-environmental program, may affect the increase in the number of new farmers willing to implement these programs. In south-eastern region of Poland, the natural packages are realized more willingly, and receiving payments is the main incentive that convinces farmers to join agri-environment program. Implementing the agri-environmental program on farms in this region of Poland contributed both to improvement of water quality, reduction of soil erosion on a farm, and on the other hand to reduction of the livestock population. Increased employment of agri-environment advisor, especially botanists and ornithologists, would facilitate farmer participation in environmental programs.

The study was conducted in the years 2005-2008 in the fields of the Experimental Station Swadzim (52^o26’ N; 16^o45’ E) belonging to ZDD Gorzyń, property of the Poznań University of Life Sciences. Two experiments with PR 39G12 maize cultivar were conducted in fields, where previously maize was sown in a six-years monoculture. The aim of the study was to evaluate the effects of natural fertilizers, straw or intercrop applied together with mineral fertilizers. We investigated whether this approach can reduce the negative effects of maize cultivation in monoculture system and at the same time help to increase the silage yield. The assessment of plant response was made on two soil classes. It has been shown that the use of natural fertilizers, straw or an intercrop (rye with vetch), reduced the negative effects of maize growing in monoculture and led to a significant increase in the dry mass yield of whole plants on IIIa soil class.

In the years 2010-2012 the effect of plant density was studied on the yield of the aboveground parts and tubers of Polish cultivars of Jerusalem artichoke, Albik and Rubik. The experiment was carried out on a light soil of a good rye complex in a randomized block design. The experimental factors included: I) Jerusalem artichoke cultivars: Albik, Rubik, II) plant density: 2, 4, 6, 8 plants· m^-2. Cvs. Albik and Rubik, on average over the three years of research, did not differ in the dry matter yield of the aboveground parts and tubers. In the year with a higher rainfall total during growing season, cv. Albik gave higher yields, while in the year with a dry spell from July to September, cv. Rubik yielded higher. With a density of 6 and 8 plants· m^-2 the dry matter yield of the aboveground parts was significantly higher compared with a density of 2 plants· m^-2. The lowest tuber yield was obtained at a density of 2 plants· m^-2, a significantly higher one at a density of 4 plants· m^-2. Increasing plant density from 4 to 6 or 8 plants· m^-2 did not result in an increase in the tuber yield. Increasing density from 2 or 4 plants· m^-2 to 6 or 8 plants· m^-2 caused a decrease in the number and weight of tubers per plant as well as in the average weight of a single tuber.

The scope of genetic variation in concentrations of minerals in potato tubers and effects of mineral fertilizers application, pesticides, growth regulators on the mineral content and the relationships of these elements in potato tubers, was analyzed. The study discussed the phenotypic variation range determined by genetic and environmental variability. The hypothesis presupposes that increased yields generated either by the application of mineral fertilizers and/or the use of cultivars with higher fertility may lead to a reduction in the concentration of minerals in potato tubers, was verified in the study.