A four-year field experiment was conducted in north-eastern Poland. The aim of the study was to determine the direct and residual effects of increasing doses of meat and bone meal (MBM) on the available phosphorus content of soil and the total phosphorus content in crops above ground biomass or grain. Experimental factor I was MBM dose (1.0, 1.5, 2.0 and 2.5 t/ha/year, and 2.0, 3.0, 4.0 and 5.0 t/ha/every second year), and experimental factor II was the year of the study (four consecutive years). The application of increasing MBM doses to slightly acidic soil insignificantly decreased its pH, but it did not change soil classification. The use of MBM as a fertilizer increased the levels of available phosphorus, compared to the treatments with mineral fertilization. The grain of winter triticale and winter wheat and the green matter of maize contained higher concentrations of phosphorus after the MBM application, in comparison to the plants receiving mineral fertilization. Phosphorus uptake by winter wheat and maize plants (dry matter basis) was higher in treatments with MBM (in particular applied every second year) than in treatments with NPK fertilization. Irrespective of the frequency of MBM application, phosphorus uptake by winter rapeseed was considerably lower, compared to the control plants.

A field experiment was conducted in 2011 – 2013 in Poland. The objective of this study was to determine the effect of increasing doses of meat and bone meal (MBM) on the mineral nitrogen (Nmin) and available phosphorus (P) content of soil and the soil pH. Changes in the content of NH4+-N, NO3--N and available P in soil were affected by MBM dose, experiment duration, weather conditions and crop species. Soil amended with MBM was more abundant in mineral N and available P. The lowest concentration of NO3--N and the highest concentration of NH4+-N were noted in the first year of the study, because the nitrification process requires a longer time. MBM had no influence on the accumulation of Nmin in soil, whereas the concentration of available P increased significantly throughout the experiment. The soil pH decreased with increasing MBM doses. After the application of the highest MBM doses soil pH classification was changed from neutral to slightly acidic.

Phytoextraction relies on plants with a high capacity to absorb heavy metals and remove them from the soil. The objective of this study was to analyze the potential of sunflower (Helianthus annuus L.) and white mustard (Sinapis alba L.) for phytoextraction of Zn-contaminated soil. Research was based on a strict pot experiment conducted in a greenhouse. Seven treatments were established with increasing Zn concentrations: 0, 25, 50, 100, 200, 400, and 600 mg Zn kg -1 air-dry soil. The first tested plant was fodder sunflower. In the following year, white mustard was sown in the same pots. Plants were harvested at the end of the flowering stage. The toxic effect of Zn on sunflower yields occurred at the contamination level of 200 mg Zn kg -1 soil. In the second year of the experiment, a significant decrease in mustard biomass took place in response to 400 mg Zn kg -1 soil. The contamination level of 600 mg Zn kg -1 soil resulted in complete plant death. Plant growth was not inhibited even at high tissue Zn concentrations of 515 mg Zn kg -1 sunflower DM and 422 mg Zn kg -1 mustard DM. The 2-yr cropping system did not contribute to a significant decrease in soil Zn content. Despite high concentrations of Zn in sunflower and mustard plants, total Zn uptake accounted for only 1% to 8% of the Zn rate introduced into the soil. However, in the long run, the growing of crops could reduce Zn contamination levels in the soil. The relatively high tolerance of sunflower and white mustard for Zn contamination and rapid growth of these species are possible alternatives for phytoextraction and phytostabilization of Zn-contaminated soil.

Phytoremediation is one of the ways of removing toxic metals from soil. Phytoremediation relies on using plants which are highly capable of absorbing heavy metals to remove them from soil. In order to determine the effect of the degree of soil contamination with zinc on the production of biomass and concentration of zinc in ryegrass, a pot experiment was carried out, consisting of 6 treatments in which gradually increasing doses of zinc were used: control treatment (without zinc), 25, 50, 100, 200 and 400 mg Zn kg-1 off soil. The experiment was conducted on two types of soil, different in the cation exchange capacity: sand and sandy loam. The tested plant was perennial ryegrass cv. Nira. The toxic effect of zinc on the growth of ryegrass was much more pronounced in the case of plants grown on sand than on sandy loam. When ryegrass was grown on sand, the toxic effect of zinc was observable even when the lowest rate of zinc had been introduced to soil: the biomass of the first cut was considerably depressed. On sandy loam, the toxic effect of zinc was not manifested until the highest rate of the contaminant had been introduced to soil (400 mg Zn kg-1 of soil). The experiment has demonstrated the presence of a strong, statistically verified correlation between the content of zinc in soil extracted in 1 M HCl and the concentration and uptake of this metal in the following cuts of ryegrass. The concentration of zinc in grasses from the first cut was very high: 1660 mg Zn kg-1 d.m. on sand and 1200 mg Zn kg-1 d.m. on sandy loam. A one-year cultivation of perennial ryegrass only slightly lowered the content of zinc in soil. Although the concentration of zinc in harvested grass was very high, the total uptake was just a small percentage (1-2%) of the quantity of this metal introduced to soil. Perennial ryegrass cv. Nira is capable of accumulating very high amounts of zinc and is well tolerant to a high content of Zn in soil, which is why it can be used for sowing on land polluted with this heavy metal.

Nitrogen fertilization combined with microelements is an effective way to provide nutrients to plants, which are essential for obtaining high-value crops. The aim of this study was to evaluate two N fertilizer rates (150 and 200 kg ha-1) and four Mn fertilizer rates (0.0, 0.5, 1.0, and 1.5 kg Mn ha-1) on the N, Mn, Zn, Cu, and Fe content and composition of fatty acids in winter wheat (Triticum aestivum L.) grain. An increase in the N fertilizer rate increased (12.7%) the Mn content and decreased (10%) the Cu content of wheat grain. Regardless of N fertilization, foliar application of Mn at 1.5 kg ha-1 contributed to the highest Zn (28.4 mg kg-1) and Fe (58.4 mg kg-1) content in the grain. In an analysis of lipid fractions, the highest value of the coefficient of variation was recorded for C18:0 (16.3%-low variation). Nitrogen and Mn fertilization were most strongly correlated with the Mn content of grain (r = 0.356, r = 0.391, respectively). The 200 kg N ha-1 treatments combined with 1.0 kg ha-1 Mn and 150 kg ha-1 N without Mn were correlated with the content of C:18:0, C18:1c11, C18:1c9, and monounsaturated fatty acids in the grain. The application of 200 kg ha-1 N with 1.5 kg ha-1 Mn was correlated with the Fe, Zn, and Mn content of the grain. The remaining fertilization treatments were correlated with the content of C18:3, C18:2, polyunsaturated fatty acids (PUFA), and the C18:2/C18:3 ratio in the grain. Results indicated that the application of 200 kg ha-1 N beneficially affected the PUFA content in the winter wheat grain and can therefore be used to obtain raw material with increased nutritional value. The human organism does not synthesize PUFA, so they must be taken with food (or supplements); winter wheat grain can be a good source because it contains more than 60% PUFA.