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The aim of this study was to investigate the sorption behavior and mechanisms of the organic pesticides on soil. To establish the sorption isotherms of six commonly used pesticides (acetochlor, atrazine, diazinon, carbendazim, imidacloprid, and isoproturon), laboratory equilibrium studies were performed at extended concentration ranges on brown forest soil using the batch equilibrium technique. The pesticide concentrations in the equilibrated liquid phase were quantified with high-performance liquid chromatograph by ultraviolet detection. The adsorption processes could be described by a single-step (Langmuir) isotherm for acetochlor and carbendazim, by a two-step curve for diazinon, isoproturon, and atrazine, and by a three-step curve for imidacloprid. A nonlinear mathematical model-derived from the Langmuir equation-has been developed that represents well the detected single-step and multistep shaped adsorption isotherms. The interpreted model was found to fit the experimental data well and allows the description of the adsorption profile with great precision. The altered adsorption activity, which was indicated by the step arising on the plot, may represent the existence/occurrence of a different specific type of adsorption mechanism. This binding force starts to operate simultaneously at a critical concentration of solute in the studied soil-pesticide system. The parameters calculated from the equation provide an opportunity to estimate the extent of absorption constant, adsorption capacity, and concentration limit characteristic to the measured stepwise isotherms.

We evaluated the feasibility of extracting organic pesticides in soil using a hot-water percolation apparatus at 105 degrees C and 120 kPa pressure. Efficiency of the method was assessed by extracting six selected pesticides (acetochlor, atrazine, diazinon, carbendazim, imidacloprid, and isoproturon) from previously equilibrated soil at 13.6-65.8 mg/kg concentration range. Studies were performed on brown forest soil with clay alluviation (Luvisol). The method developed was compared to the traditional batch equilibrium method in terms of desorbed amount of pesticides from soil and extraction time. Pesticides in the liquid phase from the batch sorption experiment and in the effluent from the hot-water percolation were quantified by high-performance liquid chromatography with UV detection. The results of the percolation experiment are in close correlation with those of the conventional soil testing method. Desorbed quantities by hot-water percolation were 85% acetochlor, 62% atrazine, 65% carbendazim, 44% diazinon, 95% imidacloprid, and 84% isoproturon, whereas using batch equilibrium method 101, 66, 64, 37, 81, and 90% were desorbed, expressed as the percentage of the adsorbed amount of pesticide on soil following equilibration. The average time for hot-water extraction was 3.45 min, in contrast to the 16 h time consumption of the traditional batch method. The effect of temperature on stability of selected compounds was also evaluated using pesticide-spiked sand without soil. Recoveries of analytes ranged between 84.6 and 91.1% with reproducibility of 7.9-10.2%, except for diazinon, for which recovery was 59.4% with 14.4% relative standard deviation since decomposition occurred at elevated temperature. The percolation process has been described by a first-order kinetic equation. The parameters calculated from the equation provide an opportunity to estimate the amount of compound available for desorption, the rate of desorption processes in the studied soil-pesticide-water system, and modeling the leaching process to obtain additional information on the environmental behavior of the examined pesticide.

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During the last century, potato (Solanum tuberosum L.) has become a worldwide elementary staple food. The key reason for this process is the high nutritional value of potato as a carbohydrate source, storability, and ease and divergent uses. Breeding programmes resulted in new cultivars with improved yield potential (Brown 2011). In spite of a significant biological progress during the recent decades, actual yields in many countries are unsatisfactory and fail to rise further. Between 2004 and 2013, the world average yield increased from 17.7 t/ha to 19.5 t/ha (FAOSTAT 2016). The estimated potential yields for Poland (PL) and the Czech Republic (CZ) are 39.7 t/ha, 47.7 t/ha (Supit et al. 2010), while the actual yields during 2003-2013 ranged from 15-24 t/ha and 23-30 t/ha for PL and CZ, respectively, and from 15-24 t/ha for Albania (AL) (FAOSTAT 2016).The key reason of much lower real yields is not rooted only in the course of weather, but also results from low efficiency of applied nitrogen (N) fertilizer. The current mineral nutrition management in the Central Europe crop production is N-oriented, almost neglecting other nutrients, like phosphorus (P) and potassium (K). As a result, harvested yields are highly year-to-year variable (Grzebisz et al. Potato yield is affected by an interaction between nitrogen (N) and potassium (K) supply. This hypothesis was verified in a series of field experiments conducted during 2010-2013 in Albania (AL), Czech Republic (CZ) and Poland (PL). The two-factorial experiment was founded on relative scales of K (0, 50, 100, and 150%), and N application rates (75% and 100%) of the recommended doses, which were country-specific. The average tuber yield was doubled for AL, increased by 50% for PL, and by 15% for the CZ in response to K and N interaction. These differences are caused by an increase in the apparent nitrogen efficiency (ANE), which rose significantly by the progressive Krates. Maximum average ANE of 90 kg tubers/kg N was recorded in AL; it was 2-fold lower in CZ. Top average apparent potassium efficiency (AKE) of 65 kg tubers/kg K was recorded in PL; it was 4-times lower in CZ. The relationships between AKE and ANE clearly demonstrate the tight interaction between the N and K, and its effects on potato yield. However, a sound K application management should be adjusted to the local edaphic and climatic conditions.

A new, easily applicable soil extraction method has been developed using the coffee percolator principle. The hot water percolation method (HWP) was examined on 36 soils with different properties. During hot water percolation the available, desorbable, easily soluble elements are extracted by hot water (102-105°C) at 120-150kPa pressure. The average time for one extraction is 2.6mm. It is possible to carry out kinetic measurements too. Nearly every nutrient is extracted by this method in measurable quantities, and the macroelements in appreciable quantities. The variation coefficient ( C V % ) of the method is in average 11%. The results are in close correlation with those of conventional soil testing methods and with the nutrient uptake of the sunflower and ryegrass used as test plants.

Due to the increasing number of sewage cleaning plants, the amount of sewage sludge also increases. We have to solve the environmentally sound disposal of the sludge. Results of many experiments show that sewage sludge and sewage sludge compost can be recycled as nutrient suppling material in agriculture. Municipal sewage sludge compost could cause the occurrence and accumulation of toxic elements in the soil. A small-plot experiment with sewage sludge compost was established in the spring of 2003. The applied compost contains 40% sewage sludge, 25% straw, 30% rhyolite, 5% betonite. The small-plot experiment was retreated in the autumn of 2006, 2009, 2012and 2015. There are 4 treatments in five blocks, where the sewage sludge compost was applied at a rate of 0, 9, 18 and 27 tha -1 and then ploughed into the soil. Triticale as autumn cereal, maize and green pea as spring crops were sown in crop rotation every year. Plant samples were collected before harvesting. In this paper the results of crop yield between 2010-2012 are presented. Crops of triticale and maize were higher in the treated plots than in control one in 2010 and 2011. Treatment effect was not observed on green pea yield.The results show that the effect of applied compost doses depends on plant species and time. Our aim is to maintain this unique long-term experiment for studying the composted sewage sludge as a nutrient and organic matter source, applying it similarly to the farmyard manure.