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Soil temporarily excluded from agricultural production is exposed to several factors which deteriorate its chemical, physical and biological properties. To preserve the productive potential of uncropped soil, it is recommended that the soil surface be turfed. In the spring of 1996, a field experiment was set up in Knopin (municipality Dobre Miasto, the Province of Warmia and Mazury), where the effect of the type of a plant cover or its lack (bare fallow) on the physical and chemical characteristics of soil was investigated. One of the goals of the study reported below, which was conducted between 2000 and 2007, was to determine how the way uncropped farmland was maintained affected the content of nitrogen in soil. The experiment comprised five treatments: bare fallow, traditional fallow, a fallow field cropped with eastern galega (Galega orientalis Lam), or a mixture of eastern galega (Galega orientalis Lam.) and smooth brome (Bromus inermis), and finally a fallow field seeded with smooth brome (Bromus inermis). The set-aside land was only sampled for soil, while the biomass which grew on it every year was left in the field. Soil for analyses of physical and chemical characteristics was sampled from the 0-25 cm topmost layer, four times a year (April, July, September and November). During the research, there was only one agritechnical treatment performed, such as the mechanical weeding of the bare fallow field. The best way to maintain land excluded from agricultural production for many years proved to be by seeding it with eastern galega or its mixture with smooth brome. A far less beneficial solution was to grow smooth brome alone. When there was no grass on a field to synthetise free nitrogen, the content of nitrogen mineral forms in soil decreased. However, the depeletion of nitrogen from turfed soil was distinctly lower than from the soil kept as a bare fallow. Consistent eradication of weeds most probably ensured much better conditions for organic matter mineralisation. Hence, the concentration of nitrates in soil under a bare fallow field was the highest. The absence of a plant cover, as many authors maintain, exclude the possibility of the uptake of mineral nitrogen forms, which is conducive to their leaching into the deeper layers of a soil profile, a consequence which mostly affects nitrates. The study reported underneath supports this opinion. In the light of our results we can conclude that farmers should be discouraged from keeping set-aside land as a bare fallow. [ABSTRACT FROM AUTHOR]

Two types of digestate were used for the fertilization of Virginia fanpetals: from Virginia fanpetals (DVF) and from maize fermented with bovine slurry (DMS). A dose of DVF was determined according to the fertilization demand for K, and because of a low content of N in this waste, some treatments were designed with a supplementing dose of mineral nitrogen. In turn, the DMS was supplied to soil in an amount sufficient to meet N fertilization demand, but due to a small concentration of K in the waste, some treatments were designed with supplementing potassium nutrition. In both cases, the digestates were an exclusive source of phosphorus. Because of the low amount of N supplied to soil with DVF, the use of this element was 97 and 68%. The use of P from digestate by plants varied from 13 to 42%. Due to the lower amount of P brought in with DMS, Virginia fanpetals used more efficiently P from this type of waste. The use of K ranged from about 30 to 205%, which means that when the quantities of this element brought in with DMS were small, the plants absorbed very intensively the K contained in soil. The macronutrients from digestate were used by the plants at least as efficiently as the ones originating from mineral fertilizers. Therefore DVF or DMS is suitable for the fertilization of Virginia fanpetals. [ABSTRACT FROM AUTHOR]

Soil is an extremely valuable component of ecosystems. Even during a break in intensive soil cultivation planned for a few years, the set-aside land should be given the best possible protection. The biomass left on fallow fields is a priceless source of humic compounds, which entails positive influence on resources of nutrients, their mobilisation and availability to future crops. The field experiment comprised five treatments: 1 - bare fallow, 2 - a plot swarded with goat's rue (Galega orientalis Lam.), 3 - natural fallow, 4 - a plot swarded with a mix of goat's rue (Galega orientalis Lam.) and aweless brome (Bromus inermis), 5 - a plot swarded with aweless brome (Bromus inermis). During the experiment, agronomic treatments were limited to mechanical weeding of the bare fallow. Plant material was sampled from the swarded plots for chemical analyses. Each year, after the growing season finished, soil samples were taken. The soil was sampled at the depth of 0-25 cm. The tests showed that the way set-aside and fallow land is maintained significantly modified both the total nitrogen and organic carbon concentrations in soil. Goat's rue and its mixture with aweless brome most evidently favoured increased concentrations of organic carbon and total nitrogen. Bare fallow prove to be the least favourable solution. The tests have also demonstrated that the amount of organic carbon compounds accumulated in soil depended on the biomass of plants on a given set-aside field and the nitrogen accumulated in that biomass. [ABSTRACT FROM AUTHOR]