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).

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.

Crop fertilization with sulfur is an important part of agricultural practices, as is the systematic increase in soil organic matter content. Materials of waste origin constitute a source of plant-available sulfur, as well as soil organic matter. The study was to verify the hypothesis assuming that combining waste sulfur pulp and its mixtures with organic materials enables simultaneous soil enrichment with readily available sulfur and organic matter. A 240-day incubation experiment was conducted, on two soils: very light and heavy; with two sulfur doses applied to each soil (20 and 40 mg S/kg d.m. for very light soil, and 30 and 60 mg S/kg d.m. for heavy soil). The sulfate sulfur content in the incubated soil material, treated with the addition of sulfur pulp and its mixtures with organic materials, increased significantly up to day 60 and then decreased. The application of these materials significantly increased the content of available sulfur and decreased the pH value of the incubated material. The effect of the introduced materials on dehydrogenase activity depended on soil granulometric composition (the impact of the applied materials on the activity of these enzymes in very light soil was small, and in heavy soil, their activity was usually limited by the presence of introduced materials). Application of the studied materials had little effect on the total organic carbon content in the incubated soil material (a significant change in the value of this parameter, in relation to the control soil, was recorded in some treatments of heavy soil).

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.

There is a potential for using sulfur waste in agriculture. The main objective of this study was to design a granular fertilizer based on waste elemental sulfur. Humic acids and halloysite were used to improve the properties and their influence on soil properties. This is the first report on the use of proposed materials for fertilizer production. The following granular fertilizers were prepared (the percentage share of component weight is given in brackets): fertilizer A (waste sulfur (95%) + halloysite (5%)), fertilizer B (waste sulfur (81%) + halloysite (5%) + humic acids (14%)), fertilizer C (waste sulfur (50%) + halloysite (50%)) and fertilizer D (waste sulfur (46%) + halloysite (46%) + humic acids (8%)). Basic properties of the obtained granulates were determined. Furthermore, the effect of the addition of the prepared fertilizers on soil pH, electrolytic conductivity, and sulfate content was examined in a 90-day incubation experiment. Enrichment with humic acids and the higher amount of halloysite increased the fertilizer properties (especially the share of larger granules and bulk density). In addition, it stabilized soil pH and increased the sulfur content (extracted with 0.01 mol·L⁻¹ CaCl₂ and Mehlich 3) in the soil.

With a shortage of sulfur in the soil and an increasing world population and, thus, food consumption volume, the demand for this important nutrient is likely to increase, both globally and regionally. The purpose of this model incubation study was to evaluate the effect of fertilizer granule applications containing elemental sulfur, halloysite and phosphate rock on the content of the bioavailable form of sulfur and phosphorus, as well as dehydrogenase activity and pH value of two soils differing in granulometric composition and chemical parameters. In addition to the standard procedure of analysis of variance, the authors propose various methods of advanced statistical analysis: regression modeling, including simple regression and multiple regression, or multivariate methods of grouping objects and traits resulting in the creation of heatmaps. With respect to the control, the application of fertilizer granules generally had no significant effect on the content of available phosphorus and the activity of dehydrogenase, and had little effect on the degree of acidity of the soils tested. There was a greater effect of introducing fertilizer granules on the content of sulfate sulfur in heavy soil than in medium soil. Using advanced statistical techniques revealed relationships between the studied soil parameters and changes in their values as affected by the experimental factors.