Optimization of fertilization enables to obtain a yield of high quality and quantity, brings economic profits, and reduces environmental threats. The aim of the three-year field experiment was to determine the efficiency of fertilization with a new fertilizer available on the Polish market and containing nitrogen (N) and sulfur (S) in proportions designed for cereals cultivation (30% N and 6% S as ammonium nitrate and ammonium sulfate). Other treatments included no fertilization; fertilization with ammonium nitrate (34% N); fertilization with standard nitrogen and sulfur fertilizer with N supplementation with ammonium nitrate. Nitrogen doses were 150, 200, and 250 kg N ha⁻¹. Sulfur was applied in doses of 30, 40, and 50 kg S ha⁻¹. A beneficial effect of using fertilizer containing N and S in proportions designed for cereals cultivation was observed. The highest mean optimal nitrogen dose and maximum winter wheat yield were recorded for the new fertilizer (217 kg N ha⁻¹ and 8251 kg ha⁻¹, respectively). Sulfur supplementation with the new fertilizer significantly increased apparent nitrogen recovery (mean values 48.9%, 44.6%, and 40.6% for doses 150, 200, and 250 kg N ha⁻¹, respectively), agronomic efficiency (11.1 and 8.6 kg kg⁻¹ N for doses 200 and 250 kg N ha⁻¹, respectively), and physiological efficiency (24.7 kg kg⁻¹ N for dose 200 kg N ha⁻¹).

Optimization of plant nutrition is a very important part of primary production quality systems. Crop fertilization is the most important agrotechnical measure because it determines the amount and quality of the yield. Moreover, excess fertilization intensifies the eutrophication processes and the greenhouse effect. The study aimed to assess the suitability of slow-release fertilizers in cultivation of carrot subspecies Daucus carota L. ssp. sativus in the integrated production system. The objective was realized on the basis of a strict field experiment set up on a clay loam soil with low nutrient content. The dose of fertilizer was the experimental factor. The fertilizers were applied during the formation of the ridges. Traditional fertilizers (ammonium phosphate, potassium salt, ammonium nitrate, and a multi-component fertilizer Polifoska 6), as well as a multi-component fertilizer with slow release of nutrients, NPK Mg (18-12-24-4), were used. In individual variants of the experiment, different fertilization strategies were applied: integrated production fertilization, traditional fertilization, and fertilization based on the use of slow-release fertilizers. The control treatment comprised of unfertilized plants. The efficiency of nitrogen fertilization was evaluated based on agronomic efficiency, partial factor productivity, physiological efficiency, and removal efficiency. Fertilization strategy significantly impacted the quantity of obtained yield. In the control sample, prior to mineral fertilization, the crop yield was 33.53 Mg·ha⁻¹. The largest yield was 82.30 Mg·ha⁻¹.The largest yields were obtained from plants fertilized with a combination of slow-release fertilizers, with nitrogen introduced in the form of ammonium phosphate, and through conventional fertilization. The highest productivity and environmental efficiency were obtained in treatments with fertilization according to the principles of integrated production and with slow-release fertilizers. In terms of environmental efficiency, the best results were obtained through nitrogen fertilization using 400 kg of slow-release fertilizers. The use of slow-release fertilizers in carrot cultivation can significantly improve the efficiency of fertilization, both in terms of production and environmental protection.

Sulfur deficiency has been recognized as a limiting factor for crop production in many regions of the world. A 120-day incubation experiment was conducted to assess the effect of the applied waste elemental sulfur on sulfur bioavailability in soil. Four doses of sulfur were applied: 10, 20, 30 and 60 mg S kg⁻¹ dry matter (d.m.) of soil. In order to assess the effect of soil pH adjustment on sulfur oxidation, the research was conducted on two sets of soil samples: one set of soil samples had natural pH, and the second one was limed before sulfur application. Application of waste sulfur slightly affected the soil pH, and increased the content of available sulfur in soil proportionally to sulfur dose. A beneficial effect of waste sulfur application on soil dehydrogenase and catalase activity was found. Liming reduced soil acidity, and significantly increased sulfate content and soil enzymatic activity. Waste elemental sulfur may be an alternative source of sulfur, supplementing the deficiencies of this element in soils. The described way of sulfur waste reuse corresponds with the increasingly common approach to create waste-free technologies in all economy.

Elemental sulfur of waste origin may be a valuable sulfur source for plants. However, assessing the suitability of environmental use of a waste material should confirm there is no harmful effect of the material on soil environment. The purpose of the incubation experiment was to assess the availability of selected elements (P, K, Ca, Mg, Fe, Mn, Zn, Cu, Cr, Ni, Pb, Cd) in soils supplemented with waste elemental sulfur. The research was conducted on two soils: light and heavy, and with three sulfur doses applied to each soil. Available forms of elements in the soils were extracted 60 days after the waste introduction, with three reagents: 0.01 mol L⁻¹ CaCl₂, Mehlich 3 and 1 mol L⁻¹ HCl. Additionally, to determine the impact of the introduced sulfur on soil acidification, soil pH was periodically checked during the experiment. The sulfur addition intensified acidification of the light soil, and, to a lesser extent, of the heavy soil. The acidifying effect was stronger when the sulfur dose was higher. The content of available forms of elements in the soils depended mainly on the strength of the used extractants (generally, the highest amounts were extracted with 1 mol L⁻¹ HCl and the lowest with 0.01 mol L⁻¹ CaCl₂). The effect of sulfur introduction on element availability was small. No harmful effect on element availability in soils was stated.