The purpose of this study was to evaluate the effect of ash from combustion of plant biomass of energy willow and Pennsylvania fanpetals on yields of willow grown as an energy crop and on soil properties. A three-year pot experiment was carried out on substrates with a loamy sand texture. Ash application rates were based on the potassium fertilisation demand. An incubation experiment was carried out to determine the effect of biomass-based ash on soil properties. Three soils with textural categories were incubated for 3 months with the ashes, the doses of which were determined on the basis of the hydrolytic acidity of soils (¼; ½ and 1.0 Hh). It was found that ashes generated from burning willow or Pennsylvania fanpetals can be applied instead of phosphorus, potassium and magnesium fertilisers in the cultivation of energy willow. The plant uptake of P, K and Mg from the ashes did not diverge from their absorption by plants when supplied with mineral salts. The application of these alkaline ashes will increase the soil content of phytoavailable forms of phosphorus, potassium and magnesium. The examined ashes enriched the soil with micronutrients.

Abandonment of crop production on agricultural lands for several or more years is a widespread practice not only in Europe but also around the world. Economic and political considerations lead to the abandonment of crop production on the poorest lands, although sometimes agriculturally valuable lands are also excluded from farming. Fallow land can be afforested, designated as a dedicated protection area, exposed to natural succession, or used to grow biomass for energy purposes. However, the most important role of agricultural land should be to ensure food safety. The set-aside land with high production potential should be treated in a special way. While lying fallow, the soil can have its fertility sustained or even improved considerably. To this aim, uncultivated land should be properly protected by growing a permanent cover of plant species which will have a positive influence on the soil’s physical, chemical, and biological characteristics. Depending on the geographical location, different plant species will have a beneficial effect on set-aside soil. Given economic and environmental considerations, the best solution is to sow a mixture of grasses and legumes, which can improve substantially the biodiversity on fallow fields, raise the soil’s fertility, ensure high CO₂ sequestration ratios, and influence beneficially the soil’s nutritional status and nutrient management. Soil protection can be provided for many years with little effort. The most recent reports implicate that it is possible to achieve several economic and environmental aims simultaneously in the course of the management of land excluded from agricultural production. These aims include the improvement of biodiversity, control of greenhouse gas emissions, generation of energy, and readiness to resume production of commodity plants. Proper management of fallows corresponds well with the challenges defined in the Green Deal for Europe or the US Green New Deal.

The aim of this incubation experiment was to evaluate the effect of Tenebrio molitor L. frass on selected chemical and microbiological properties of acid peat. The optimal rate of mealworm frass in the substrate for growing ornamental trees and shrubs was determined. Acid peat was fertilized with frass or urea at five nitrogen (N) rates: 0, 50, 100, 200, and 400 mg dm⁻³. Mineral N content and electrical conductivity increased, and calcium content decreased in peat with increasing N rates. Similarly to urea, frass increased the ammonification rate at the beginning of incubation and the nitrification rate from the second week of incubation. Higher frass rates increased the abundance of plant-available nutrients (N, P, Mg, K, and Na) in acid peat. Frass undesirably decreased the counts of bacteria with antagonistic activity against soil-borne plant pathogens. Regarding the abundance of functional genes, the optimal N rate was 100 mg dm⁻³, which promoted the growth of N-fixing and chitinolytic bacteria. Higher N rates promoted the development of aerobic spore-forming bacteria, which produce antibiotics that can be used as biocontrol agents. Moderate fertilizer rates contributed to N accumulation in bacterial biomass. These preliminary findings, which indicate that insect frass can partially replace mineral fertilizers, are promising and can be used in pot and field experiments testing various plant species.

Fodder galega is a perennial, wintering plant, which in recent years has been gaining popularity, mainly because of its useful characteristics. Many researchers have noted its large yield potential and exceptional adaptability to various environmental conditions. The purpose of this study was to collect the most up-to-date knowledge about this valuable plant, a member of the Fabaceae family. Green fodder, especially that made from young plants, possesses very good biochemical parameters which allow it to be used in the nutrition of animals including poultry. Plantations of fodder galega can be set up on highly diverse soils, and in all systems of management. The yielding potential of this plant is appreciated on all farms: organic, extensive and conventional ones. Many scientific studies have demonstrated the usefulness of fodder galega for the protection of farmland that is periodically excluded from farming. In recent years, reports have been published suggesting the high potential of this plant for the acquisition of inexpensive energy from its biomass. Moreover, many scholars have emphasised the medicinal applications of fodder galega. The advantages of the cultivation of fodder galega are (1) its low nutritional requirements; (2) a lack of threats from the specialised pests; and (3) its positive effect on soil fertility. It is recommended that areas having undergone several years of fodder galega cultivation act as very good forecrop for plants with high nutritional requirements.

Smooth brome (Bromus inermis L.) is a species of perennial grass with growing economic importance. Initially, this species had attracted interest as a source of animal feed. Over the years, the interest in smooth brome increased significantly due to the growing knowledge about its advantages. The aim of this study was to explore the contemporary significance of smooth brome. This plant is characterized by a high tolerance to many negative environmental factors, such as periodic droughts, low temperatures and salinity, which contributes to its constant presence in the landscape of many countries. The moderate soil requirements of smooth brome, combined with the effective use of soil resources and rational nutrient utilization, contribute to high biomass yields that can reach 13 t/ha DM. The usefulness of this grass species in various management systems has been recognized in numerous research studies. Smooth brome can generate benefits in many branches of the economy. This efficient energy plant is used in paper production, and it is also recommended for the protection of fallow land or the reclamation of degraded land. Smooth brome prevents erosion, enhances biodiversity, and provides shelter for many animal species. This species fits well into the current assumptions of agricultural policy and increasingly demanding environmental standards. According to the latest guidelines, modern agriculture should pursue economic and environmental goals simultaneously. In this context, smooth brome constitutes a valuable link in sustainable development. Due to its numerous advantages, smooth brome not only provides high-quality feed and biomass but also effectively sequesters CO₂, improves soil fertility and enhances biodiversity, which makes it an important element of agriculture and environmental protection.

Phacelia tanacetifolia Benth. is a species of annual plant that has been gaining importance in recent years. Initially, it was treated as an ornamental plant and valuable only to bees. Over the years, this species has become more widely known, and many more of its advantages have been discovered. The aim of this study was to learn about the contemporary economic importance of Phacelia tanacetifolia Benth. The extraordinary, rapid increase in the plant’s biomass means that it is valued as a fodder plant and at the same time is included in the group of leaders among catch crops. It is characterized by low requirements for soil quality. The main advantage of this plant is its high resistance to drought and frost. A great advantage of this plant is its high drought resistance. It is recommended for sowing both in monoculture and in mixtures with other species. In the light of current standards and assumptions, it fits perfectly into the framework of sustainable development. It is a valuable link in the biodiversity chain, as well as support for a number of ecosystem services such as CO₂ sequestration, retention of nutrients in the soil or protection of its structure. Phacelia is seen as having great potential as a plant that provides food for a number of pollinators. The latest research also focuses on assessing the possibility of using it for energy purposes (biogas). Efforts are being made to introduce phacelia on a wider scale to eliminate crop monocultures and significantly strengthen biodiversity in a given area. Phacelia plays an important role in various agronomic systems and effectively supports the protection of the natural environment. The contribution of this species to the development of ecosystem services to date is undeniable. It should be assumed that this plant will continue to significantly support a number of activities for sustainable development.