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The operation of an agricultural biogas plant is associated with the formation of a large amount of digestate. The basic trend in digestate management, after taking into account its physicochemical properties, should be its use as a fertilizer. The possibility of the agricultural use of digestate as a fertilizer was determined. Digestate obtained from the agricultural biogas plant was tested for the content of macronutrients and heavy metals. The content of macronutrients was also determined in soil for winter rape cultivation. The analysis showed an increase in the yield depending on the digestate dose applied. In addition, an increase in the fat and protein content was found in winter rape seeds. The best results of mean values were obtained during the application of the 50,000 L ha−1 dose. The average diameter of the stem base was 1.48 cm. The average height was 36.20 cm. The seed yield was 3.44 t ha−1. The thousand seed weight was—5.34 g. The fat and protein contents were 43.62% and 22.95%, respectively. By applying a digestate dose of 50,000 L ha−1, the highest content of macronutrients, as well as polyunsaturated fatty acids (PUFA) (31.17%), monounsaturated fatty acids (MUFA) (61.89%) and saturated fatty acids (SFA) (6.87%), was recorded.

Geographic object-based image analysis (GEOBIA) is a primary remote sensing tool utilized in land-cover mapping and change detection. Land-cover patches are the primary data source for landscape metrics and ecological indicator calculations; however, their application to visual landscape character (VLC) indicators was little investigated to date. To bridge the knowledge gap between GEOBIA and VLC, this paper puts forward the theoretical concept of using viewpoint as a landscape imageability indicator into the practice of a multi-temporal land-cover case study and explains how to interpret the indicator. The study extends the application of GEOBIA to visual landscape indicator calculations. In doing so, eight different remote sensing imageries are the object of GEOBIA, starting from a historical aerial photograph (1957) and CORONA declassified scene (1965) to contemporary (2018) UAV-delivered imagery. The multi-temporal GEOBIA-delivered land-cover patches are utilized to find the minimal isovist set of viewpoints and to calculate three imageability indicators: the number, density, and spacing of viewpoints. The calculated indicator values, viewpoint rank, and spatial arrangements allow us to describe the scale, direction, rate, and reasons for VLC changes over the analyzed 60 years of landscape evolution. We found that the case study nature reserve (“Kózki”, Poland) landscape imageability transformed from visually impressive openness to imageability due to the impression of several landscape rooms enclosed by forest walls. Our results provide proof that the number, rank, and spatial arrangement of viewpoints constitute landscape imageability measured with the proposed indicators. Discussing the method’s technical limitations, we believe that our findings contribute to a better understanding of land-cover change impact on visual landscape structure dynamics and further VLC indicator development.

The aim of the research was to determine the impact of biofuels from waste materials of plant and animal origin on the parameters of the common rail power supply system in the utility engine. The tests included identification of power system operation parameters in the whole load range of the tested engine, taking into account the limit and diagnostic parameters of the injectors operation. Then, for certain parameters, the engine injectors were tested on the test bench: injection pressure in the range of 25-135 MPa, injection time in the range of 200-1600 μs. In the tests, as reference fuel for testing injectors were used diesel fuel and three types of methyl esters of higher fatty acids: vegetable, animal and WCO origin. The measurements for individual fuels were made in the operating temperature range 30-60°C. The tests have shown significant changes in the volume of the fuel injection rates depending on the fuel used. Particularly, visible changes concerned the power system operation parameters for high engine speeds and the maximum working pressure of the common rail system in the engine.

The studies were conducted in a forest settlement in Roztocze National Park (eastern Poland). The aim of the study was to evaluate the vegetation of two pastures depending on the type of use in the context of grassland protection, identify the trends of species composition changes, and analyse the yield and nutritional value of the biomass in the context of animal welfare. The studies were conducted on permanent grasslands varying in terms of fertility and location. Both sites were pastures where native breeds of livestock (Polish Lowland sheep of the Uhrusk and Polish Konik) were grazing. The fertile pasture was represented by the developing Lolio-Cynosuretum association, while the poor dry pasture -by a community with Common Bent (Agrostis capillaris L.) and a community with Mouse-Ear Hawkweed (Hieracium pilosella L.). The greatest changes over time were observed in the mowed site in the fertile pasture (increased share of tall grasses) and in the abandoned poor dry pasture (increased share of herbs and weeds). Livestock grazing conducted from 2010 influenced the stabilisation of the species composition. Tree and shrub seedlings were systematically eaten by livestock, which evidences a positive impact of grazing on the preservation of permanent grasslands in Roztocze National Park where forest ecosystems predominate. The assessment of the species composition and yielding indicated that the fertile pasture was characterised by good value while the poor pasture -low or sufficient value. In terms of nutrient yield and content, these pastures were poor or very poor, and their nutritive potential was largely dependent on the meteorological conditions. While the livestock density in the pastures, ranging from 1.1 to 1.5 LSU ha -1 in the years under study, was appropriate, grazing should be limited in the summer months, particularly in periods of drought, by reducing the number of animals or by additional feeding to ensure their welfare.

SUMMARYThis paper discusses the problem of determining the number of observations necessary to apply the nonparametric Mann-Whitney test. We describe the method given by Noether (1987) for determining a sample size which guarantees that the Mann-Whitney test at a given significance level α has a predetermined power 1-β. The presented theory is tested by calculating the empirical power in computer simulations. The paper also raises the issue of the method of rounding the determined sample size to an even number when the sample is divided into two equinumerous subsamples.

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In the era of sustainable agriculture, the issue of proper and precise implementation of agrotechnical operations, without harmful effects on the natural environment, begins to play an important role. Statistical tools also become important, for example, when assessing the malfunction of plant cultivation equipment. The study presents a comparison of six nonparametric bootstrap methods used for construction of confidence intervals for the expected value of an average diameter of droplet stains following the spraying process. The simulation tests were carried out based on experiment with nozzle sprayer Lechler 110-03 using two spray nozzles: a new one and an old one. It was assumed that the distribution of the droplet stain size was consistent with the lognormal distribution. The paper considers the influence of the sample size, mean value and standard deviation of the droplet stain diameter on the interval range as well as on the estimated coverage probabilities of the confidence intervals. It was shown that in general these methods can be applied for this purpose. For the double bootstrap method and the studentized method, the empirical confidence levels of the constructed intervals turned out to be less distinct than the assumed level but the lengths of these intervals were greater than the lengths of intervals obtained using the other four methods.