Abstract: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 P 2 O 5 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.

A b s t r a c tPhytosociological 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 mixturewinter 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.

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.

A pot experiment with an additive design and three series was conducted to test competition between spring barley and Italian ryegrass under different soil moisture conditions. The experimental factors were as follows: 1. type of sowing – mixed sowing and pure sowing; 2. water supply – plants supplied with water to meet their full requirements and 50% water supply reduction. The study covered five phenological development stages (BBCH) of spring barley: emergence (10–13), tillering (22–25), stem elongation (33–37), heading (52–55), and ripening (87–91). The competitive effects were evaluated based on relative yield (RY), relative yield total (RYT), competitive balance (CB), and relative efficiency index (REI). Spring barley and Italian ryegrass competed for resources throughout the growing season. Competition intensity was found to increase until the heading stage, and it decreased towards the end of the growth cycle. More intense competition was observed under reduced water supply. Spring barley dominated over Italian ryegrass from the tillering stage to the ripening stage. In mixed populations, Italian ryegrass captured the available resources more effectively than spring barley from the stem elongation stage until the end of the growing season, particularly in the treatment with optimal water supply

The paper analyses the weeds community in oats cultivated at different position in two crop rotations: after potato (in the rotation system with 25% share of oats) and twice after oats (with its 75% share) during the years 1990-2000, using the diversity of species indicators (by Simpson and by Shannon-Wiener), homogeneity of species by Simpson and communities similarity ratios. The dependence of biological indicators on the weather conditions and the dependence of oats grain yield on the number and diversity of species were assessed. Diversity and homogeneity of species in communities of weeds in the field of oats showed high differences from year to year of studies and dates of measurements (stage of oats tillering, end of its vegetation). To a lesser degree they changed under the influence of the position in the rotation system. With the passage of years the number of weeds during the spring period gradually increased. The analyzed parameters showed the differentiated dependence on the weather conditions. The communities form years with similar weather conditions did not show analogy in individual density and species. No significant dependence between the yield and the diversity of weeds was confirmed

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.

With global warming, the problem of soil water deficit is growing in Central Europe, including Poland, and the use of catch crops is recommended to mitigate climate changes. This study aimed to determine the influence of water deficit on phosphorus (P) content and accumulation in the above-ground biomass of spring barley and Italian rye-grass growing separately and in the mixture, and on the inter-species interactions between these crops. The study was based on a pot experiment established in accordance with the additive design. The experimental factors were as follows: A. water supply of the plants: an optimal dose and a dose reduced by 50% in relation to the optimal dose, and B. the sowing type: barley sown as a single species, rye-grass sown as a single species, and barley with rye-grass catch crop. Based on the P accumulation in plant biomass, the relative yield of barley and rye-grass, the total relative yield, and the competitive equilibrium index were determined. Water deficit had no effect on the P content in the plants, but it reduced the P accumulation in barley stems, leaves and spikes, as well as in rye-grass stems and leaves, from the emergence to the end of plants’ growing period, both when the plants were sown as a single species and as a mixture. Barley was a stronger competitor than rye-grass. Inter-species competition occurred at the stem elongation and heading of barley. The intensification of inter-species competition for P under water deficit conditions should be taken into account when recommending the undersowing of barley with rye-grass for sustainable agriculture.

<p>A pot experiment was conducted in a greenhouse in Olsztyn, Poland, in the period 2010–2012. The aim of the study was to examine whether soil water deficit would change biomass volume and distribution of pure sown spring barley and red clover as well as growth rate during their joint vegetation and mutual interactions. The interactions between spring barley and red clover were of a competitive character, and the cereal was the stronger crop. The strength of this competition increased in time with the growing season. Through most of the growing season, the competition was poorer in water deficit conditions.</p><p>The impact of clover on barley before the heading stage showed facilitation symptoms. Interspecific competition reduced the rate of barley biomass accumulation and decreased stem and leaf biomass towards the end of the growing season. Intensified translocation of assimilates from the vegetative parts to grain minimized the decrease in spike biomass.</p><p>Water deficit stress had a more inhibitory effect on the biomass and growth rate of barley than competition, and competition did not exacerbate the adverse influence of water deficit stress on barley. Competition from barley significantly reduced the biomass and biomass accumulation rate of clover. Water deficit stress did not exacerbate barley’s competitive effect on clover, but it strongly inhibited the growth of aboveground biomass in pure-sown clover.</p>