Recycling phosphorus from waste for fertilization purposes appears to be an alternative for non-renewable sources and a solution for managing harmful products of civilisation. Fertilizers from secondary raw materials are considered to be safe to the environment. This study presents an assessment of the effects of five new biofertilizers made from sewage sludge ash and/or animal bones on the content of cadmium and lead in the soil, in wheat grains and straw (test plant), in the mass of the the accompanying weeds and in the post-harvest residues. Biofertilizers were produced in the form of suspension or granules and activated using Bacillus megaterium or Acidithiobacillus ferrooxidans bacteria. They were tested in four field experiments. The Cd and Pb contents of the soil and plant material were determined using the ICP-MS technique. Similar to superphosphate, new biofertilizers showed no change in the Cd and Pb contents of the soil and plants biomass when applied at amounts up to 80 kg; P₂O₅ ha⁻¹. Both Cd and Pb in the soil and plants occurred naturally, and the amounts were within the acceptable standards. Biofertilizers from renewable raw materials, with low toxic element contents, are not thought to pose a hazard to the soil and plants when applied in reasonable amounts. They can be a substitute for conventional phosphorus fertilizers.

Phytosociological data were collected in 1994–1996 in plots (relevés) at the Research Station for Organic Farming and Conservation Breeding of the Polish Academy of Sciences in Popielno included in a large-area experiment conducted according to the concept and method proposed by Prof. S. Nawrocki. In a four-field crop rotation (root crops – spring barley undersown with red clover and grasses – red clover/grass mixture – winter triticale), each field was divided into two management units, organic and integrated. Data were collected in relevés by the Braun-Blanquet method, each year at the peak of the growing season. Weed abundance (% cover) in cultivated fields and the number of weed species (species richness) in crops were determined, which provided a basis for calculating the Shannon-Wiener indices of species diversity and evenness, and the Rényi profiles. The qualitative (species) and quantitative structure of weed communities was compared using the Sørensen index. A total of 115 weed taxa (species, subspecies and varieties) were identified in the examined agro-phytocenoses. Echinochloa crus-galli, Chenopodium album, Matricaria maritima subsp. inodora, Capsella bursa-pastoris, Thlaspi arvense and Stellaria media were the most abundant. Weed infestation was slightly higher in the organic farming system than in the integrated system. Organic farming contributed to higher weed species diversity in root crops, red clover/grass mixtures and winter triticale. Weed species richness was reduced in red clover/grass stands, while root crops and – to a lesser degree – spring barley undersown with red clover and grasses decreased weed species diversity. The species composition and in particular the quantitative structure of weeds were affected by crop species and cultivation regime rather than by the farming system. Weed communities of crops grown under organic and integrated farming systems were more similar with regard to species composition than the quantitative structure.

One means of enriching plants with microelements is agronomic biofortification, whereby the mineral composition of plants is stimulated through appropriate fertilization. A fertilizer component which has received much attention in recent years is sulphur. Due to the significant reduction in SO₂ emissions from industrial sources to the atmosphere, a progressive deficiency of this nutrient has been observed in soils in Poland and other parts of the world. Therefore, a study was undertaken to assess the effect of different application rates (20 and 40 kg·ha⁻¹) and forms (elemental and ionic) of sulphur on the content of selected micronutrients (Mn, Fe, Zn, and Cu) and their proportions (Fe : Mn) in the grain of the Antek variety of spring barley. In a three-year single-factor field experiment setup on luvisols with low content of sulphur, the following fertilizers were tested: ammonium sulphate, potassium sulphate, and Wigor S (80% elemental sulphur and 20% bentonite). It was demonstrated that, in the fertilization of spring barley, supplementation of NPK with sulphur can be regarded as an agronobmic method of biofortification of grain with micronutrients because it beneficially affects the content of manganese, iron, zinc, and copper in the grain. An increase in the content of these micronutrients was found in the grain of plants fertilized with sulphur in comparison to plants that were not fertilized with this nutrient in each of the growing seasons. Ammonium sulphate, compared to the other fertilizers tested, had the greatest impact on the content and uptake of all micronutrients, with the exception of zinc. Marked differences in the effect of the application rates of 20 and 40 kg·S·ha⁻¹ were observed only for fertilizers containing the ionic form of sulphur. The beneficial effect of sulphur on the biofortification of microelements in spring barley grain indicates the need to include this nutrient in cultivation of this species.

Earthworm species composition, the density of individuals, and their biomass were investigated in spring barley and faba bean fields in a long-term (52-year) experiment conducted at the Production and Experimental Station in Bałcyny, in north-eastern Poland (53°40′ N; 19°50′ E). Additionally, post-harvest residues biomass, soil organic matter (SOM), and soil pH were recorded. The above traits were investigated using two experimental factors: I. cropping system—continuous cropping (CC) vs. crop rotation (CR) and II. pesticide plant protection: herbicide + fungicide (HF+) vs. no plant protection (HF−). A total of three species of Lumbricidae were found: Aporrectodea caliginosa (Sav.) in both crops, Aporrectodea rosea (Sav.) in spring barley, and Lumbricus terrestris (L.) in faba bean. The density and biomass of earthworms were unaffected by experimental treatments in spring barley fields, whereas in faba bean CC increased and HF+ decreased earthworm density and biomass in comparison with CR and HF− respectively. Total post-harvest residues in faba bean fields were higher under CC in relation to CR and under HF+ compared with HF− treatment in both crops. Compared to CR, CC increased soil pH in spring barley fields and decreased in faba bean fields. Experimental factors did not affect SOM. Earthworm density and biomass were positively correlated with SOM content.

In recent years, sustainable agriculture has revitalized interest in crop rotations and their effects on crop performance and agroecosystem biodiversity, including weeds. This article used winter rye as an example and focused on the crop rotation (CR) impact on species, taxonomic and functional diversity of weed communities and analysed the contribution of crop rotation to protecting yield and regulating weed abundance. Long-term continuous rye cropping (CC) provided a background for comparison. Two variants of plant protection were also adopted: herbicide application (H+) and no plant protection (H−). The data from the 10th, 30th and 50th years of the experiment were included in the analysis. Diversified crop rotation with no chemical protection resulted in a satisfactory rye yield and reduced weed abundance—especially problem species—without a decrease in weed species diversity or functional diversity. When rye was grown under crop rotation, the herbicide application had no effect on yield protection, but it was harmful to weed biodiversity. The rye yield correlated negatively with weed biomass, but did not show a link with weed biodiversity. Continuation of long-term experiments as a research basis for contemporary and future scientific challenges is necessary.