Linseed (Linum usitatissimum L.) is a traditional oilseed crop in Europe that represents a valuable alternative for cropping systems because of the high quality of the seed oil, which is being increasingly appreciated by consumers, food, cosmetic and ecomaterials industries. The aim of this study was to evaluate the influence of linseed variety and year of production in relation to weather conditions on seed yields, oil content and its quality, with a focus on human nutrition value, through a field study carried at four different locations in Slovenia. Six early French linseed varieties were studied: Recital, Niagara, Princess, Altess, Comtess and Duchess. The seed yield was significantly affected by the year of production (413 kg/ha higher in 2012 compared to 2013), the location and the variety. The environmental factors that negatively affect seed yield are high temperatures in summer, water shortage and wet and cold soil in spring. The highest seed yield was reached at mid-heavy soil (1907 kg/ha) in the region with higher precipitation amount, while the lowest on light soil (1052 kg/ha) in the region with a lower precipitation amount. Comtess and Altess varieties, followed by Duchess, would be recommendable for Slovenian environmental conditions. Comtess variety gave the significantly highest oil yield. There were no significant differences in oil content between varieties. The content of α-linolenic acid was highly related to genetic and environmental factors. The ratio of omega-3 and omega-6 fatty acids was recognized as favorable for human health for all studied varieties. The content of α-linolenic acid in seeds from the Altess, Comtess and Duchess varieties exceeded the averages of 2012 and 2013, at 50.3% and 51.6%, respectively. The omega-3:omega-6 ratio ranged from 3:1 to 4:1 among varieties.

Green agro waste can be turned into compost, which can then be used as an organic fertilizer, thus reducing the environmental impact of food and feed production. This research is focused on finding a feasible on-farm composting treatment of plant biomass to produce high-quality compost. Three different composting treatments were prepared and followed (with different additives at the start—biochar (BC) and effective microorganisms (EM), no additive (CON); covering and not covering the pile; different start particles size). Samples were analysed for nutrient concentrations, phytotoxicity and bacterial and fungal presence after seven months of composting. In 100 g of dry matter, the average compost contained 2.7 g, 0.38 g and 1.08 g of N, P and K, respectively. All investigated treatments contained more than 2% of total nitrogen in dry mass, so they could be used as a fertilizer. The highest nutrient content was observed in compost of small particle size (˂5 cm) and added biochar (11 kg/t fresh biomass). However, this compost had the least bacteria and fungi due to very high temperatures in the thermophilic phase of this pile. According to the radish germination index, the prepared composts have no phytotoxic properties and are stable and ready to use in plant production. Taking the cress germination test into consideration, they provided a nutrient-rich and biostimulative soil amendment. All three final composts were stable in terms of respiration rate, growth and germination tests. Results have shown that hop biomass after harvest has great potential for composting.

The aim of this research is to find a simple mathematical model due to sum of effective temperatures and rainfalls from second germination after spring pruning till the technological maturity of hop cones, in order to achieve reliable prognosis of alpha-acids content in hop cv. Aurora. After mathematical analyses of experimental data by Eurequa Formulize 0.96 Beta software 17 equations were offered, and after substituting the values of dependent and independent variables in all equations only one equation was chosen with p = 0.034 (p<0.05). This equation is not reliable in extremely drought year if crop evapotranspiration ET0 in July is higher than 4.5, primarily because of negative influence on formation and development of hop glandular trichomes. Considering achieved results it is possible to suggest following general equation for alpha-acids accumulation in hop: y = [(k 1 w) − k 2 − (k 3 w 2)/x] ÷ (−10) ↔ ET 0 July ≤ 4.5. Where y is alpha acids content in dry matter (%), x = sum of effective temperatures and w = sum of rainfals, both from second germination after spring pruning till technological maturity of hop cones. Coefficients k 1 , k 2 and k 3 are determined for cultivar Aurora (53.8, 453 and 1.33, respectively).

Harvesting of white hop shoots might be justified if they can be shown to be beneficial to human health. The aim of the present study is to determine the effects of hop cultivars and year of production on total phenolics, antioxidant potential, microelements and pesticide residues. Biomass per plant was highly variable among the cultivars (3.1-7.1 g dry mass per plant) and depended on hop cultivar and year (2009-2011). Total phenolics as chlorogenic acid equivalents (CAE) on dry mass basis varied from 0.60 to 1.80 mg/g, and showed significant effects across hop cultivar and year. The radical scavenging activities of the samples collected in years 2010-2012 ranged from 11 to 19 μg CAE. Ferric reducing activity was <0.01, with significantly different effects across hop cultivars (pC≤0.05) and year (py≤0.05) observed only in 2012. Traces of microelements and potentially active compounds from the use of pesticides in white hop shoots of Humulus lupulus ‘Dana’ were analysed. The content of zinc in the hop shoots on dry mass basis was very low (4 mg/kg), and it was below the limit of detection in the soil. The content of copper in the hop shoots was also very low (2.3 mg/kg), while in the soil it was below the critical emission (100 vs 300 mg/kg, respectively). All 182 active ingredients from the residues of the previously used pesticides were below the limits of detection. It can be concluded that these white hop shoots are better antioxidants than hop cones and hop leaves, and that they do not contain any pesticide residues.

Technology that would result in a high-quality product with minimal environmental impact throughout the on-site composting process of hop biomass after harvest has not yet been developed. It is crucial to introduce composting practices that do not result in a detrimental leachate impact. Three different composting procedures that vary in terms of initial biomass particle size, additives, and pile covering were investigated. Each pile was built from 15 t of fresh hop biomass after harvest (leaves and stems), leachate was collected during the composting season (September to the end of April), and biomass was sampled and analyzed to identify good practices as well as gaps that need to be filled. Leachate quantity differed significantly in terms of the composting procedure and time stamps. There was a strong linear correlation between the amount of precipitation and leachate quantity (0.86), NH₄ leached amount (0.87), and total N leached amount (0.92), but not the total P amount. The composting procedure had a significant impact on the quantity of the NH₄ leached amount. The majority of the NH₄ was lost in the second month of composting. The maturation phase was the most critical for NO₃ loss since it had the highest amount of leached NO₃ and the greatest variances among the composting protocols. Considering leachate it is recommended that a membrane is used at all times during the maturation phase as well as during any heavy precipitation expected in the thermophilic phase. Whether the cover is also needed for the entire duration of the thermophilic phase (due to emission) is a matter of further research.