Contamination of soil by toxic elements is a global issue of growing importance due to the increased anthropogenic impact on the natural environment. Conventional methods of soil decontamination possess disadvantages in forms of environmental and financial burdens. This fact leads to the search for alternative approaches of remediation of contaminated sites. One such approach includes phytoremediation. Phytoremediation advantages consist of low costs and small environmental impact. Several fast-growing energy plant species are suitable for phytoremediation purposes. Our article focuses on the phytoremediation potential of energy woody crops of Salix and Populus, and energy grasses Miscanthus and Arundo, which are grown primarily for biomass production. This approach links the environmentally friendly and economically less demanding remediation approach with the production of the local sustainable form of energy that decreases dependency on external energy supplies. Energy plants are able to provide high biomass yields in a short period of time, they are resistant against abiotic stress conditions and have the ability to accumulate toxic substances, thus helping to restore the desirable soil properties. The phytoremediation research is very interdisciplinary in its nature. In order to implement phytoremediation practices together with bioenergy successfully, it is crucial to involve site owners, local people, farmers, technology providers and consultants, remediation experts, sustainability assessors, regulatory agencies and certification bodies, biorefineries, financial sponsors, NGOs and other voluntary organizations. Some disadvantages and challenges of phytoremediation are also indicated.

With increasing demand for sustainable production, the need to effectively utilise site-based resources increases. One such resource is the remaining crop residues, both above and below ground, after harvest. In order to assess the magnitude of this resource, this study determined the plant nutrient contribution of residues from 17 different crops in seven different regions of Slovakia over a nine-year period. The soil profile 0.0–0.3 m was taken into account at belowground residues sampling. The results showed that winter rape, mustard, corn maize, triticale, winter rye with straw and sunflower left the most residues, exceeding 8 tons of dry biomass per hectare. Root crops (sugar beet, potatoes) and peas left less than 3 tons of residual dry biomass per hectare. Using these data, the nutrient potential coefficient, i.e. the amount of nutrients left by production of one ton of the main product was calculated by polynomial regression. With these coefficients and the known yield of a given crop, it was possible to calculate how much nitrogen, phosphorus and potassium each crop leaves in the soil after harvest. It was found that the amount of nitrogen left ranged from 20 to 132 kg, phosphorus from 2 to 24 kg and potassium from 13 to 218 kg per hectare. This has to be taken into account when calculating the fertiliser requirement of the subsequent crop in order to achieve better resource utilisation, thereby reducing the risk of eutrophication and improving farm profits by reducing expenditure on fertiliser.

Due to continuous single nitrogen fertilization, we hypothesized a built-up deficiency of micronutrients in crops that would limit plant growth and crop quality. In 2-year field experiments using urea-N fertilized grain maize (Zea mays L.), hybrid KWS 2376 at 0, 120 and 240 kg N ha⁻¹ crop uptake of Zn, Mn, Cu and Fe was studied at DC 32, DC 61 and in the grain harvested. Micronutrient contents at DC 32 stage – 1st node (aboveground phytomass) and DC 61 – flowering (ear leaf) were all at levels indicative of adequate micronutrient supply to the crop. At both sampling occasions the Fe:Zn and Fe:Mn ratios were adequate implying that Fe did not inhibit the uptake of Zn and Mn. The application of nitrogen increased the Fe content at the 1st sampling in both years; in the second year the same was also the case for the Zn content. Nitrogen nutrition increased the contents of Mn and Fe at the 2nd sampling only in year 2; in the other treatments no changes were observed in the micronutrient contents. Micronutrient correlations in the grain were discovered between Zn and Mn contents and between Fe and Mn contents. In the second year the highest N-rate significantly increased the Fe and Zn content of the grain compared with the lower rates of nitrogen fertilization. Grain yields were not affected by the rate of nitrogen and ranged between 13.65 and 14.34 t ha⁻¹ (1st year) and between 13.68 and 14.18 t ha⁻¹ (2nd year). Nitrogen fertilization did not reduce the content of micronutrients in the plant or grain of maize. It is evident that the continuous single use of N fertilization so far has not resulted in a micronutrient deficiency of the plants limiting the nutrient density of the grain or reducing its quality.

The presented paper deals with the analysis of potential differences between organic waste compost (C_BD), vermicompost (C_VER) and mineral fertilizer (MF; 27% of N) applications affecting the quality of arable soil by influencing microbial activity therein. The selected types of compost represent alternatives to conventional organic fertilizers, which are, however, not available to Czech and Slovak farmers in sufficient amounts. Their mutual comparison and the comparison with organic fertilizers aim to provide farmers further information about their influence on arable land and thus to give them the possibility of deciding on the most suitable amendments. To demonstrate the effect of these amendments, six variants were prepared: one without the addition of fertilizers; two variants with the addition of 40 Mg/ha of C_VER and C_BD; one variant with the addition of double dosed C_VER (80 Mg/ha), and the remaining two variants were fertilized only with MF (0.22 Mg/ha) and with the combination of C_VER (0.20 Mg/ha) and MF (0.11 Mg/ha). Substrate induced respiration (SIR), basal respiration (BS), microbial carbon (C_mic) and enzymatic activities (hydrolysis of fluorescein diacetate—FDA, dehydrogenase activity—DHA, and phosphatase activity—PA) were used to evaluate the effect of C_BD, C_VER and MF application on the soil quality. Both organic and mineral amendments affected BS and SIR. The highest BS and SIR rates were found in variants with compost application (C_VER and C_BD). All variants treated with the mineral fertilizer showed the lowest level of enzyme activities; lower by about 30% in comparison with variants where C_VER, C_BD and the combination of MF and C_VER were applied. We found insignificant differences between the individual types of compost. More importantly, we compared the situation at the beginning of the experiment and after its end. It was found that the application of mineral fertilizers automatically led to the deterioration of all enzymatic parameters, on average by more than 25%, as compared with the situation at the beginning of the experiment. However, when the mineral fertilizer dose was supplemented with organic amendments (C_VER), this negative effect was eliminated or significantly reduced. Furthermore, both composts (C_VER and C_BD) positively affected plant biomass production, which reached a level of production enhanced by the MF. Results clearly showed that the application of both compost types could be used to improve soil quality in agriculture.

Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, the scientific journal of the Mendel University in Brno, Czech Republic

The main goal of our research was to compare the mixed intercropping (MC) of winter wheat (Triticum aestivum) and white clover (Trifolium repens) with the sole cropping of Triticum aestivum, during two growing seasons (2012–2014), in a lysimetric experiment. We aimed to investigate the effect of the above growing system on total biomass production, grain yield and leaching of mineral nitrogen (N_min). Four variants of intercropping (0 kg N/ha; 112 kg N/ha; 112 kg N/ha + 1.25 L of humic acids/ha; 70 kg N + 0.65 L of humic acids/ha) and two variants of sole cropping (0 kg N/ha; 140 kg N/ha) were used. Research results showed a good potential for growing wheat in the mixed cropping system without any negative effect on grain and total biomass production. No significant differences were found between the variants where winter wheat was grown with white clover (70 and 112 kg N/ha), and variants with sole wheat (140 kg N/ha), in both years of the experiment. The loss of N_min from the soil was affected by the application of N fertilizer and mixed intercropping system. During the experiment, the loss of N_min was higher by 20% in the variant using the sole winter wheat (140 kg N/ha), than in the MC variants.