In the experiment adsorption characteristics of different soil types (humic sand, meadow soil, leached chernozem and meadow solonec) was examined on the basis of adsorption isotherms for Cr(III)-picolinate. The Langmuir equation was used to describe the isotherms by which the amounts of metal ions actually and maximally adsorbed by the soils were determined concerning the given complex. A comparison was made among the organically bound Cr(III)-picolinate, an inorganic Cr(III) compound and a Cr(VI) form examined in a previous study. Based on the adsorption isotherms, adsorption capacity of the Cr(III)-picolinate was found 20 times smaller on sandy soil and 50 times smaller on the chernozem comparing to that of the inorganic Cr(III)-chloride, thus, the bio-availability of the chromium for the plants is 20 and 50 times higher in case of the given soil types. For the well-known toxic Cr(VI)-form, the adsorption was 2 times higher in case of sandy soil and 5 times higher for chernozem than in case of the organic Cr(III)-complex compound.
Bioavailability of pesticides is determined by two major factors: soil characteristics and pesticides’ chemical feature. These factors result in a definite adsorption capability whose extent varies on a large scale. By revealing interactions between pesticides and soils it is of high interest to model bioavailability of widely used pesticides, as it is a key element in terms of prospective toxicological aspects. Our work signifies steps forward improving pesticide soil mobility prediction models as we created model systems representing correctly natural relations. Comparison of different solvent extraction methods proved to be an efficient tool to gain information on the bioavailability of some widely used pesticides as well as to model actual environmental processes.
Comprehensive comparison has been made between different experimental methods by applying 5 extraction models showing diverse efficiency in extracting capability of pesticides. In some cases chloroform excelled in mobilizing pesticides from soil, however mostly application of humic acid solution as extraction model was found to be at least as efficient as methanol, chloroform or CaCl2-solution.
Four chemically much different pesticide (simazine, acetochlor, chlorpyrifos and diuron) were applied to two soil types (both sandy and brown forest). The extracted amounts were determined by GC/MS technique. Adsorption coefficients (Kd) were also calculated for the examined samples.
Obtained results for Kd indicated that chemical feature of pesticides seemed to be of utmost importance in terms of soil binding capability preceding the relevance of soil characteristics. Adsorption capability of chlorpyrifos proved to be the most pronounced preceding simazine and the least prone to bind to soil acetochlor and diuron
In our research a chernozem soil sample formed on loess was collected from an area under cultivation. Our aim was to determine the lead adsorption capacity using a soil column experiment. The study showed saturation of lead content of the soil. The lead accumulation capacity of Lactuca sativa L. was measured in the sections of roots and leaves applying pot experiments. It could be observed that the lettuce accumulated lead easily from the chernozem soil. The lead content was increased in the analyzed sections of the plants against an increasing lead content.
The Hungarian fertilizing recommendation systems use AL soil test for the evaluation of potassium supply. The 0.01 M CaCl2 is a definitely milder extractant, it extracts the easily soluble and exchangeable potassium amount. Its European introduction was already taken into consideration in 1994. The research project on this topic is started in several european countries, also in Hungary at the Department of Agricultural Chemisty of Agricultural University of Debrecen. Another advantage this multielement method is that the different element-ratios can also be calculated.
The Baker-Amacher extractant’s principle is that it contains a known amount of K, P, Mg in the CaCl2 solution. During the soil extraction adsorption and desorption process take place, so the adsorption or desorption can be calculated from the original and the final concentrations.
In this paper we introduce the results of comparing analysis of the samples (n=630) from Soil Information and Monitoring System. Our aim was to measure the use of new extractants beside conventional extractant (AL) for the evaluation of K-supply would be reasonable.
It can be stated that there is a medium close relationship (r=0.75) between AL-K and 0.01 M CaCl2-K. My calculations confirmed the results of former examinations, and proved that the two extractants don’t extract and change the same rate of K-fractions. We found that regression between 0.01 M CaCl2 and AL depend on texture classes, pH classes, amount of lime, and organic matter content of soils.
Comparing the relations between AL and Baker-Amacher we find relatively loose correlation (r=0.45). We stated that there are K-fixing soils among soils considered to be well supplied with potassium by AL. This might be caused by the high amount of mineral clay and the quality of mineral clay. We stated that the dK averages show that the Hungarian nutrient-supply categories characterize generally well K-supplement of soil.
It can be stated that it would be necessary to use new extractants to specify evaluation of plant available K. We found that the 0.01 M CaCl2 and Baker-Amacher extractants could complete usefully the AL procedure and could help effective potassium fertilization.
Plant-production is determined by many production-factors. Each of these factors became subject of research-works through the years, still we state, that studying their interaction is even more important. For studying these interactions we set up a potexperiment, within that the direct effect and the interactions of four factors was inspected: soil, nitrogen-supply, nickel-loading and liming. Experiments were carried out on two soil types with extremely different characters: one was a chernozem soil with good fertility and buffering capacity, the other was a shifting sand soil with low humus-content and buffering capacity. Nitrogensupply and liming was added on two levels, while nickel on three within 12 combinations on each soil types. Plant production was cut two times within the vegetation period. The amount of production and dry matter was weighted, fractured and their element-content was measured by an ICP-detector.
Ca-content on the shifting sand soil was determined by all three factors, however the interaction between nickel-loading and liming was also significant. Nitrogen and liming increased Cauptake, that is due to appropriate nutrient-supply and improvement of a better pH-value. On the chernozem soil nitrogen and CaCO3 also increased the Ca-content. This is caused by a better nutrient supply and a higher amount of available Ca-ions.
On the shifting sand soil nickel content was increasing parallel to higher nitrogen-dosages. In presence of higher nickelamount the nickel-content of plants was also increasing, still according to liming, this increment was different. On the chernozem soil nitrogen a nickel increased Ni-uptake. However, liming also had a positive effect on Ni-content, that can be explained by the high amount on colloids in the soil, the adsorption of Ni-ions on them and in presence of liming material the replacement of Ca-and Ni-ions.
The potassium-content on the shifting sand soil was different in each liming-combination. In combinations without nickel the potassium-content of limed and not limed combinations was on the same level. In not limed combinations by adding nickel potassiumcontent was increasing, while in limed combinations no change was observed. On the chernozem soil by adding liming material the amount of uptaken potassium was decreasing, that is due to the antagonism between Ca- and K-ions.
It is not possible to gain information on the risk factor representing the bioavailability and the mobility of the contaminants only on the basis of their total concentrations. Especially, in case of heavy metals, which can be charaterised with very different chemical forms and their mobil and mobilizable parts are determined by complex balances highly sensitive to the changing environmental conditions. Considering mine tailings, however, the toxic elements are basically in ore forms having low adsorption capacity, thus the heavy metal ion concentration in solution is governed mainly by the pH conditions. In Gyöngyösoroszi, the spatial distribution of the total heavy metal concentrations as well as that of pH values determining the bioavailable part of the toxic elements were estimated and by mapping the vegetation pattern, relationship was analysed among the total Zn, Cu, Pb and As concentrations, the pH and the species present. Results show that the presence of the certain plant species is highly determined by the pH on the mine tailing material, the highest vegetation density was found where the bioavailability of the toxic elements were considered the smallest as a result of the neutral pH. As a result, high diversity could be found even in places where the total zinc, copper, lead and arsenic concentrations were extreme. In addition, plant species could be identified, which are tolerant to toxic elements and present even if the pH is low and the bioavailable part of the heavy metals is relatively high.
For crop production and agricultural production, the most important natural resource is the soil that can optionally renew. Paralelly with this, soil plays a major role in the geological and biological cycle of elements. As a result of the big (geological) and small (biological) element cycles, the elements and combines neccessary for organisms can accumulate in the soil creating suitable living conditions for plants and other organisms. Soil is a heterogenous system both horizontally and vertically, and soil constituents show great variety in all the three dimensions, in addition, most of the parameters can also change between two examination dates. When talking about the factors influencing plant production, one should take into account this variation and heterogenity in time and space. When making fertilization recommendations, these factors should all be considered. In any consultation system, most of the mistakes and errors made are due to the unsatisfying soil testing and the negligence of soil heterogenity. In the practice of fertilization the biggest mistake is the improper soil sampling, then comes the methodical mistake of soil testing, which is followed by the inaccuracy of instrumental analysis and the subjectivity of result evaluation, but the latter two are negligible compared to the others. Under normal, i.e. production conditions, the quantity and distribution of nutrients in the soil are greatly dependent upon the applied technology, the amount and form of the applied natural and artificial fertilizers and the quality of fertilization.
Fertilization recommendations are needed because in the layer which is accessible for plant roots only a part of the nutrient content is available for plants in a specific production cycle. An illustration of this is that though the upper 1 m layer of an average chernozem soil contains more than 5000 kg N, 12000 kg K2O and 1500 kg P2O5 (form of expression mostly used in Hungary), the application of fertilizer doses which are just fractions of these quantities is essential. This is due to the fact that the available amount of the total nutrient content depends from the quality of soil, the environmental factors (the physical and chemical qualities of the soil) and the specific nutrient’s qualities (solubility, adsorption). Knowledge of these processes and the examination of the factors influencing the actual nutrient content are vital for working out a fertilization practice, which does not put more strain on the environment than neccessary.
All of the above mentioned should be considered when applying inputs in the fields. In a well-functioning practice that considers the economic and environmental conditions (unfortunately the present production and economic conditions do not enable an appropriate level and degree), three nutrients are supplemented generally (and were supplemented in the last decades): nitrogen, phosphorus, potassium.
Studying the nutrient balance of the Hungarian field production’s last hundred years, we can draw some interesting conclusions.
The nutrient balance became positive for nitrogen and potassium in the second half of the 1960’s, while for phosphorus it was positive from the first half of the 1960’s and this period lasted until the end of the 1980’s.
Neither before the 1960’s, nor since the 1990’s has the amount of nutrients supplemented in a specific year reached the amount of the nutrient uptake of the same year.