János Kátai

Giant Reed (Arundo donax L.): A Green Technology for Clean Environment

In recent years, biomass plants have gained considerable public attention and interesting of environmental policy makers as important renewable source for energy. In addition, exploitation of biomass plants as promising phytoremediation candidates was proposed since these plants can produce huge biomass production under low-cost conditions as well as its ability to survive in contaminated and poor soils (marginal lands). Giant reed (Arundo donax L.) has been recognized as one of the most important energy plants as a consequence of its huge dry biomass production that can reach more than 60 t ha-1 under optimal growth conditions. Nowadays, giant reed becomes promising tool for phytoremediation purposes where it shows great ability to grow in different soils with wide ranges of pH, salinity and trace metal contents. Giant reed is a tall perennial rhizomatous grass (Poaceae family), native to the freshwater regions of Eastern Asia, but nowadays considered as a sub-cosmopolitan species given its worldwide distribution. It is a hydrophyte, growing along lakes, streams, drains and other wet sites. The genus Arundo can reach the height of 14 m and is among the fastest-growing terrestrial plants. Giant reed displays unique physiological features whereby it readily absorbs and concentrates toxic chemicals from contaminated soil with no appreciable harm to its growth and development. It is one of the mostly used plants as a trace element bio-accumulator, especially via phytoremediation processes, due to its capacity of absorbing contaminants such as metals that cannot be easily biodegraded. Many reports documented well that giant reed can efficiently decontaminate polluted soils with Cu, Cd, As, Pb Ni, high content of salts bauxite-derived red mud. Microbial component in soil is considered one of the most sensitive indicators for soil contamination especially with trace metals. Where, many microbial species significantly reduce directly after exposure to such pollutants except tolerant species. However, giant reed showed capability for healing and restoring the soil microbial community within phytoremediation process. Moreover, in autoclaved soil samples, giant reed was able not only to maintain soil chemical properties, but also to induce the microbial growth of different groups such bacteria, fungi and actinomycetes in a short period. These data encourages using giant reed for phytoremediation purposes as well as for recovering steaming soil as in natural fires. This chapter reviews the scientific literatures and presents innovative findings on the ability and utilization of giant reed biomass feedstock for phytoremediation and other uses.

Potential Dissipation of Atrazine in the Soil Unsaturated Zone: a Comparative Study in Four European Countries†

A European-wide project has been undertaken to establish the potential for dissipation of atrazine in the soil subsurface environment. Samples were obtained, avoiding contamination, in four countries (Belgium, Greece, Hungary and UK) and laboratory studies carried out. In order to make comparisons between results from each laboratory, a ring experiment was carried out using common methodology for sampling, extraction and analytical techniques. Subsurface materials from each country were distributed to the other countries. Atrazine dissipation was determined in each country for all materials under the same laboratory conditions. The results of this comparative study showed generally good agreement between all laboratories. Significant potential microbiological dissipation was detected in certain samples. Where differences occurred between laboratories this was attributed to small, spatially heterogeneous microbial populations in the subsurface materials.

Relationships between the carbon content and some microbial characteristics in the different soil types

Introduction During the transformation and mineralization of the organic materials containing carbon, nutrients become available for plants. The microbes living in the soil transform these organic carbon compounds. Their activity is influenced by ecological factors, e.g. rainfall, temperature and soil characteristics, and applied agrotechniques, e.g. cultivation, fertilization, vegetation, crop-rotation and irrigation. In our paper, the relationships between the carbon content and some microbial characteristics were studied on 12 soil types in the region surrounding Debrecen.

The effect of herbicides on some microbiological parameters of carbon-cycle in maize monoculture

Oil rape is a valuable fodder because in early spring and late autumn it produces green forage used for the nutrition of domestic animals. It has been replacing sunflower and soy in colder and wetter regions. It is additionally advantageous because it leaves behind more nitrogen in soil, which is beneficial to other plants in plant rotation. There are some possible ways for the fixation of nitrogen in soil and they are as follows: by the means of oil rape straw ; by relatively long roots ; by the action of nitrogen bacteria, which perform the nitrogen synthesis within their root system, which is the case in some leguminous plants. Oil seed rape is expected to be wider used in crop rotation of West and Middle Europe, Croatia included. Due to this various sorts have been introduced and potential positive impacts have been studied in order to boost the process. This paper presents information on barley and wheat yield in case when they were sown after oil seed rape and corn. The aim of the research is to determine the presence of positive impacts upon the soil with special attention paid to a potential increase of nitrogen content after oil seed rape was grown. The preceding crops had statistically significant effect. Rape yield was significantly higher compared to the one with corn as preceding crops. Very similar results were obtained in 2007.The maize hybrids seed from three different FAO groups (FAO 400, FAO 500 and FAO 600) in four fractions (KO, KP, SO and SP) produced in two climatically different years (extremely dry 2000 and extremely wet 2001) had been different in quality and chemical composition. The effects of year, genetic specifity and seed fraction at the kernel mass, chemical composition (starch, proteins, cellulose, oil and moisture content) and seed vigour have been evaluated. The influence of agroecological conditions during two production years have been exposed at seed chemical composition and vigour indicators (cold test – CT and bulk seed electrical conductivity - EC). The genetic specificity and seed fraction had significant influence at all tested indices, with the exception of the influence of the fraction at the starch content

Correlation between the nitrogen content of soil and element uptake of maize in a pot experiment

Introduction The nitrogen content of the soil serves as a permanent nitrogen source for plants. Since a significant part of the nitrogen in the soil can be found partly in the humus materials and partly in other organic materials, plant and animal residues and in organic bounds in microorganisms, mineral nitrogen forms that are available for plant uptake account for only a few percentages of the total content. Most of the biogeochemical nitrogen transformation processes occur in the humus-rich layer of the soil between the natural vegetation and the crops via the contribution of the organisms living in the soil. The humus balance and nitrogen management of soils closely correlate. ROSSWALL (1976) estimated the nitrogen turnover of the microorganisms and the plant system to be 95% (cit. NEMETH, 1995). The transformation of organic matter in the soil is performed by the organisms living in the soil, the activity of which is largely determined by the ecological and agrotechnical factors. In our pot experiment, the changes in the soil nitrogen forms and in the biomass and nitrogen uptake of maize were determined in soils from a long-term fertilization experiment.

Influence of alternative plant nutrition methods on soil microbial characteristics in long-term experiments

The size of the arable land is constantly decreasing all over the world due to severe anthropogenic disorders. Plant production therefore has to be adapted to changing environmental conditions alon...

The effect of bentonite on soil characteristics and on biomass of the testplant in a small-pot experiment

Oil rape is a valuable fodder because in early spring and late autumn it produces green forage used for the nutrition of domestic animals. It has been replacing sunflower and soy in colder and wetter regions. It is additionally advantageous because it leaves behind more nitrogen in soil, which is beneficial to other plants in plant rotation. There are some possible ways for the fixation of nitrogen in soil and they are as follows: by the means of oil rape straw ; by relatively long roots ; by the action of nitrogen bacteria, which perform the nitrogen synthesis within their root system, which is the case in some leguminous plants. Oil seed rape is expected to be wider used in crop rotation of West and Middle Europe, Croatia included. Due to this various sorts have been introduced and potential positive impacts have been studied in order to boost the process. This paper presents information on barley and wheat yield in case when they were sown after oil seed rape and corn. The aim of the research is to determine the presence of positive impacts upon the soil with special attention paid to a potential increase of nitrogen content after oil seed rape was grown. The preceding crops had statistically significant effect. Rape yield was significantly higher compared to the one with corn as preceding crops. Very similar results were obtained in 2007.The maize hybrids seed from three different FAO groups (FAO 400, FAO 500 and FAO 600) in four fractions (KO, KP, SO and SP) produced in two climatically different years (extremely dry 2000 and extremely wet 2001) had been different in quality and chemical composition. The effects of year, genetic specifity and seed fraction at the kernel mass, chemical composition (starch, proteins, cellulose, oil and moisture content) and seed vigour have been evaluated. The influence of agroecological conditions during two production years have been exposed at seed chemical composition and vigour indicators (cold test – CT and bulk seed electrical conductivity - EC). The genetic specificity and seed fraction had significant influence at all tested indices, with the exception of the influence of the fraction at the starch content