Soil Catalase Activity Research Articles

Basic soil properties and comprehensive evaluation in different plantations in rocky desertification sites of the karst region of Guizhou Province, China

Aims Soil quality plays an essential role in vegetation restoration in the karst soil ecosystem.Many studies have reported soil quality of different plantations and vegetation successional stages in karst regions,but few have focused on the seasonal dynamics of basic soil properties.Our objectives were to investigate annual dynamics of basic soil properties of different types of plantations and evaluate soil integrated quality index(SQI).Methods We analyzed the dynamics of soil physical and chemical properties and soil enzyme activities for four sites in Puding County,Guizhou Province,China:Robinia pseudoacacia plantation(RP),Cupressus duclouxiana plantation(CD),R.pseudoacacia-C.duclouxiana mixed plantation(RD) and a non-plantation area(CK).Soil samples were collected in alternate months from September 2009 to September 2010.Soil factors were measured using general methods,and data were analyzed using SPSS 13.0 software.Important findings Soil physical properties of all three plantations had an advantage over the non-plantation area and were slightly improved within one year.There were significant differences in soil nutrients and soil pH among the four sites(p 0.01).Soil urease activity in all sites was highest in September and lowest in January.Soil invertase activities were remarkably different among the four sites(p 0.01).Soil catalase activity exhibited a unimodal peak,and alkaline phosphatase activity had a bimodal peak.Soil polyphenoloxidase activity was lowest in January and very low in RP throughout the study.Moreover,the rank of means of five soil enzyme activities was different among the four sites.The SQI of RP,CD,RD and CK was 0.748,0.406,0.590 and 0.315,respectively.In general,all three types of plantations,but especially RP and RD,could improve soil quality after conversion of farmland to forest.

Enzyme activities and glyphosate biodegradation in a riparian soil affected by simulated saltwater incursion

AbstractSoil salinization due to saltwater incursion, is a major threat to biochemical activities and thus strongly alters biogeochemical processes in a freshwater riparian of coastal estuary region. A pot incubation experiment was conducted to investigate the effects of simulated saltwater incursion on some key enzymatic activities and biodegradation dynamics of herbicide glyphosate in a riparian soil in Chongming Island located in the Yangtze River estuary, China. The results showed that saltwater addition with 10% artificial seawater significantly increased the biodegradation efficiency of glyphosate with the lowest residual concentration among all the treatments. However, glyphosate degradation was markedly decreased in the riparian soil with high levels of saltwater treatment. As compared with no saltwater treatment, the half-lives for 20% and 50% seawater treatments were prolonged by 4.9% and 21.1%, respectively. Throughout the incubation period, saltwater addition with 10% seawater stimulated the enzymatic activities in the glyphosate-spiked riparian soil, as compared to the treatment with 0% seawater. Flourescein diacetate (FDA) hydrolysis rate, dehydrogenase activity (DHA), catalase activity, and alkaline phosphatase activity in the glyphosate-spiked riparian soil treated with 10% seawater were 68.5%, 49.2%, 38.7%, and 28.6% higher than those for no saltwater treatment, respectively. The effect of 20% seawater treatment on the glyphosate-spiked riparian soil enzymatic activities fluctuated between promotion and inhibition depending on the type of enzymes. Soil enzymatic activities were severely depressed by increasing salinity level with 50% seawater treatment significantly inhibited, relative to no saltwater treatment. Especially, FDA hydrolysis rate and DHA were decreased by 73.8% and 64.8%, respectively, as compared to no saltwater treatment. Glyphosate degradation percentages were strongly positively correlated to the FDA hydrolysis rate and DHA, indicating that as compared to the other enzymes, the two enzymes contributed more to the herbicide biodegradation in the salt-affected riparian soil.

Effects of intercropping cucumber with onion or garlic on soil enzyme activities, microbial communities and cucumber yield

Soil enzyme activities, soil bacterial and fungal community structures and cucumber yield as affected by different cropping systems were evaluated in a three-successive-growing-season experiment under greenhouse conditions. Intercropping systems, in which onion or garlic were planted on the side of cucumber in the first growing season, were compared to cucumber monoculture. Only cucumber was planted in the second and third growing seasons in order to see if the impacts of intercropping in the first growing season still exist in later growing seasons. Results showed that cucumber yield increased under both intercropping systems in these three growing seasons, compared with monoculture. Increases of soil urease activities under intercropping systems were detected in these three growing seasons. Soil polyphenol oxidase activities under intercropping systems also increased in the first two growing seasons. Soil catalase activity was higher under garlic–cucumber intercropping systems than under monoculture in the last two growing seasons. PCR-DGGE analysis showed that soil bacterial community band numbers and diversity indices decreased with growing seasons under monoculture. These indices were relatively stable under intercropping systems throughout these three growing seasons, and were higher than under monoculture. Garlic–cucumber system had a more obvious effect on soil fungal community structure than onion–cucumber system. This study demonstrated that intercropping cucumber with onion or garlic increased cucumber productivity and improved soil environment at different levels. These impacts of intercropping still existed in the second and third growing seasons.

Dissipation of carbendazim and chloramphenicol alone and in combination and their effects on soil fungal:bacterial ratios and soil enzyme activities

The dissipation of carbendazim and chloramphenicol alone and in combination and their effects on soil fungal:bacterial ratios and soil enzyme activities were investigated. The results revealed that carbendazim dissipation was little affected by chloramphenicol, whereas chloramphenicol dissipation was found to be retarded significantly by the presence of carbendazim. The inhibitory effect of carbendazim on the fungal:bacterial ratios was increased by the presence of chloramphenicol, and the inhibitory effect of chloramphenicol on neutral phosphatase was increased by the presence of carbendazim. Carbendazim increased soil catalase and urease activities, but this increase was partially diminished by the presence of chloramphenicol. Little interaction was observed between carbendazim and chloramphenicol with regard to their influence on soil invertase. The results obtained in this study suggest that combinations of fungicides and antibiotics may alter the compounds’ individual behaviors in soil and their effects on soil enzymes.

Effects of conservation tillage on organic carbon, nitrogen and enzyme activities in a hydragric anthrosol of Chongqing, China

Abstract Purple paddy (Hydragric Anthrosol in FAO soil classification) is one of important soil resources in Chongqing, China. Long-term conservation tillage may alter distribution of soil organic carbon, nitrogen, and enzyme activities. The objectives of this study were to investigate the impacts of different tillage systems (conventional tillage with rotation of rice and winter fallow (CT-r) system, no-till and ridge culture with rotation of rice and winter fallow (NT-r) system, no-till and ridge culture with rotation of rice and rape (NT-rr) system and conventional tillage with rotation of rice and rape (CT-rr) system) on the depth distribution of soil total organic carbon, nitrogen and enzyme activities (catalase, intverase, and urease activity) in a purple paddy soil after 18 years. Soil total organic carbon and labile organic carbon were significant increased in surface soil layer (0-10 cm) under CT-r, NT-r, and NT-rr systems compared to that under CT-rr system. It indicated that conservation tillage practices can sequester soil organic carbon and reduced CO2/CH4 emission. Soil total nitrogen also significant increased in surface soil layer (0-10 cm) under CT-r, NT-r, and NT-rr systems with the greatest under CT-r system (36%), followed by under NT-rr system (34%), and the least under NT-r system (20%) compared to CT-rr system. No-till, ridge culture, and rotation of rice and winter fallow were increased soil catalase and urease activities, but the greatest was not observed under NT-r system, under which the catalase activities was significant decreased. Soil invertase activities were significant increased under CT-r system compared to CT-rr systems and only a little increased in 0-20 cm soil layer under NT-rr system. Conservation tillage could construct good soil biochemistry environment and maintain soil fertility, and promote agroecosystem sustainable development.

The effect of long-term organic–mineral fertilisation on selenium content and chosen oxidoreductases activity under winter wheat cultivation

The aim of the research was to determine the effect of fertilisation applying various doses of manure and nitrogen on the selenium content of soil against a background of soil catalase and dehydrogenase activity. The experiment was conducted using a crop rotation system of: potato–winter wheat+intercrop –spring barley+undersown and red clover+grasses. The soil was treated with organic fertilisation in the form of manure under potato at doses of 0, 20, 40, 60 and 80 t·ha −1, and with nitrogen at doses of 0, 40, 80 and 120 kg N·ha −1. A supplement of manure at 80 t·ha −1 resulted in the greatest significant increase in soil total selenium content of ∼100% compared with soil from control plots. We observed that interaction of the highest manure and nitrogen doses resulted in a significant decrease in the total selenium content of the soil. Selenium content in soil was statistically highly correlated with organic carbon content. Analysis of the correlation showed a significant dependence between the total selenium content in the soil and the activity of soil catalase and dehydrogenase.

Variability of soil carbon sequestration capability and microbial activity of different types of salt marsh soils at Chongming Dongtan

Variations in the soil carbon sequestration capability of different types of salt marsh soils at Chongming Dongtan and its influencing factors were studied by analyzing the soil organic carbon (SOC) content, organic matter input and microbial activities. The results indicated that the total SOC content at Area A (southeast of Dongtan, sandy soil with Phragmites communis) was only 46.11% of that of Area B (northeast of Dongtan, clay soil with mixed P. communis and Spartina alterniflora) ( P = 0.000 < 0.05), but their organic matter input per year was almost identical. These findings implied that Area B had a lower output of SOC. The microbial biomass at Area A was 3.83 times greater than that at Area B ( P = 0.049 < 0.05); the soil catalase and invertase activities at Area A, which were related to carbon metabolism, were 60.31% ( P = 0.006 < 0.05) and 34.33% ( P = 0.021 < 0.05) higher than at Area B, respectively; and the soil respiration at Area A was also higher than at Area B. These findings implied that the microbial activities at Area A were greater than those at Area B, and therefore the carbon metabolism was rapid, resulting in increased SOC output at Area A. Increased water content and salinity in the clay soil at Area B may inhibit the microbial activities, thereby reducing the decomposition of the organic matter and enhancing carbon sequestration. In addition, some artificial measures for controlling spread of S. alterniflora at Area B (mowing/digging and tillage (M + D); mowing/digging and tillage/waterlogging (M + D + W)) were found to generally improve the microbial activity of soil, thereby increasing SOC output. However, when the two different physical controlling modes were compared, the SOC and microbial activities of the soil subjected to the M + D + W treatment were relatively high and low, respectively, due to waterlogging restraining the microbial metabolism. These findings indicated that the difference in microbial activities was the important factor leading to variability in the SOC sequestration capability between Areas A and B. Additionally, with the exception of soil texture and vegetation types, environmental conditions and artificial turbulence also influenced microbial activities of soil, and hence SOC output and organic carbon sequestration capability.

Overcoming of soil contamination with pesticides in forest nurseries using the activity of microorganisms

The use of pesticides during cultivation of pine seedlings in forest nurseries results in the formation two phenotypes of teratomorph seedlings - conditionally normal and abnormal. Growing forest cultures from teratomorph seedlings leads to their low survival rate. It is known that pesticides and their metabolic products can remain in soil for many years. It is therefore impossible to rely only on natural degradation of pesticides in soil. A promising way of removing pesticides from soil is their microbiological decomposition. This method is preferable because there is a meliorative organic substance not far from forest nurseries - i.e. forest litter rich in microorganisms. The purpose of these experiments was to examine the influence of forest litter applied on pesticide decomposition in soil and morphology of pine seedlings. The rates of forest litter that were most effective in decomposition of pesticides and the activity of microbial communities in litter, depending on forest stand structure, were determined. Estimation of that action was based on the morphology of seedlings (rate of pine seedlings with normal, conditionally normal and abnormal phenotypes), intensity of CO2 emission from soil and catalase activity, which correlates with the number of soil microorganisms. The results of these experiments showed the most effective activity of forest litter at the application rate of 20 kg/m2. The number of seedlings with normal phenotype rose from 32% up to 40%. Besides, it was noted that saprophytes were most effective in pine forest litter, which is characterized by a more acid reaction of soil solution, while most others were rich in fungi. The highest number of normal phenotype seedlings, intensity of CO2 emission and activity of soil catalase were correlated with the microbiological activity of the applied pine forest litter.

Partial root-zone irrigation enhanced soil enzyme activities and water use of maize under different ratios of inorganic to organic nitrogen fertilizers

Partial root-zone irrigation (PRI) is an effective water-saving irrigation method but the heterogeneous soil moisture distribution that may affect soil enzymatic activities and crop water use. With pot-grown maize, we investigated the dry mass accumulation, crop water-use efficiency and the activities of four major soil enzymes from jointing to grain filling stages of maize plants subjected to PRI and also different ratios of inorganic to organic N fertilizers. Three irrigation methods, i.e. conventional irrigation (CI), alternate PRI (APRI) and fixed PRI (FPRI) and three ratios of inorganic to organic N, i.e. 100% inorganic (F1), 70% inorganic + 30% organic (F2) and 40% inorganic + 60% organic (F3), were applied. Compared to CI, PRI reduced total dry mass and water consumption of maize by 9.5 and 15.7%, respectively, which led to an increase of canopy water-use efficiency by 7.4%. Within the same irrigation method (CI, APRI or FPRI), added organic N increased total dry mass and canopy WUE. During the whole period, maximal soil catalase, urease and acid-phosphatase activities occurred in the wet root-zone of PRI, but maximal invertase activity occurred in the dry root-zone of PRI. When organic N was the most (F3), APRI increased soil catalase, urease and invertase activities at jointing stage if compared to CI, but PRI reduced the acid-phosphatase activity from jointing to filling stages. Soil catalase, urease and invertase activities generally increased with more organic manure, but the maximal acid-phosphatase activities occurred under moderate amount of organic N (F2). Our results indicate that APRI increases canopy WUE and the catalase, urease and invertase activities in its wet zone and organic N plays a major role in enhancing canopy WUE and soil enzymatic activities.

Response of soil catalase activity to chromium contamination

The impact of chromium(III) and (VI) forms on soil catalase activity was presented. The Orthic Podzol, Haplic Phaeozem and Mollic Gleysol from different depths were used in the experiment. The soil samples were amended with solution of Cr(III) using CrCl3, and with Cr(VI) using K2Cr2O7 in the concentration range from 0 to 20 mg/kg, whereas the samples without the addition of chromium served as control. Catalase activity was assayed by one of the commonly used spectrophotometric methods. As it was demonstrated in the experiment, both Cr(III) and Cr(VI) have an ability to reduce soil catalase activity. A chromium dosage of 20 mg/kg caused the inhibition of catalase activity and the corresponding contamination levels ranged from 75% to 92% for Cr(III) and 68% to 76% for Cr(VI), with relation to the control. Catalase activity reached maximum in the soil material from surface layers (0-25 cm), typically characterized by the highest content of organic matter creating favorable conditions for microorganisms.

Adsorption of lambda-cyhalothrin and cypermethrin on two typical Chinese soils as affected by copper

Pesticides and heavy metals pollution in soil environment has become a serious problem in many countries including China. Repeated applications of bordeaux mixture (a blend of copper sulfate and calcium hydroxide) and pyrethroid (Pys) insecticides have led to elevated copper (Cu) and Pys concentrations in vineyard surface soils. However, few studies focused on the interaction of Pys and heavy metals in the soil environment. Our previous studies had indicated the combined effect of cypermethrin (CPM) and Cu on soil catalase activity. Also, we had suggested that the addition of Cu could catalyze photo-degradation of CPM and lambda-cyhalothrin (lambda-CHT) in aqueous solution and restrain their degradation in soil. To better understand the potential influence of Cu on the fate of Pys in the soil environment, the aim of the present work was to examine the effect of Cu on the adsorption of lambda-CHT and CPM on two typical Chinese soils with different soil characteristics, which was one of the key processes controlling the fate of Pys, and to provide more information about the potential ecological risk of chemicals on the soil ecosystem. Fourier transform infrared and point charges analysis using the MOPAC program of the Gaussian system were also used to reveal the probable adsorption mechanism of lambda-CHT and CPM on soils. Two vineyard soils with different properties were chosen as experimental samples. They were sampled from 0 to 10 cm, dried, and sieved to 2 mm. Each soil was spiked with copper sulfate solution to obtain the following total soil Cu concentrations: 100, 200, 400, 800, and 1,600 mg.kg(-1). The treated soils were incubated for 2 weeks and then dried at 20 degrees C. For each soil sample and at each soil Cu concentration, the adsorption of lambda-CHT and CPM was measured using a batch equilibrium method. The concentration of lambda-CHT was determined by HPLC, and the amount of lambda-CHT and CPM adsorbed by the soil sample at equilibrium was determined by the difference between the initial and equilibrium concentrations in solution corrected by the blank adsorption measurement. Without the addition of Cu, the adsorption of lambda-CHT and CPM on Black soil is greater than that on Red soil, while the adsorption of lambda-CHT on both soils is significantly stronger than that of CPM. As the soil Cu concentration increased from 19 (or 18; background) to 1,600 mg.kg(-1), the adsorption coefficient (K (d)) of lambda-CHT decreased from 12.2 to 5.9 L.kg(-1) for Red soil, and from 26.1 to 16.8 L.kg(-1) for Black soil, whereas the CPM adsorption coefficient in both soils decreased nearly by 100% (K (d) decreased from 9.4 to 0.2 L.kg(-1) for Red soil and from 16.2 to 0.5 L.kg(-1) for Black soil). Pys adsorption is a surface phenomenon which depends on the surface area and the organic matter content. Thus, the Black soil, having higher organic matter and greater surface area than that of the Red soil, show greater adsorption affinity to lambda-CHT and CPM. In our study, the different adsorption affinity of the two Pys was obtained, which was probably attributed to differences with respect to their physical-chemical properties. Further comparison upon the two Pys was conducted. The point charges of halogen atoms in the lambda-CHT and CPM were calculated, the differences of which probably lead to the fact that lambda-CHT has a stronger binding capacity to soils than CPM. Also, FTIR spectra show that competitive adsorption occurs between CPM and Cu for the same adsorption sites, which is responsible for the obtained suppression of CPM adsorption affected by Cu. Lambda-cyhalothrin shows a significantly stronger adsorption than cypermethrin on both soils. This phenomenon may be due to several reasons: (1) lambda-CHT has lower solubility and a higher octanol-water partition coefficient value than CPM; (2) lambda-CHT consists of specific isomers, whereas CPM is mixtures of eight different isomers; (3) the chlorine and fluorine atoms in the lambda-CHT have a negative point charge, whereas the chlorine atoms in the CPM have a positive point charge. As the soil Cu concentrations increased from 19 (or 18) mg.kg(-1) to 1,600 mg.kg(-1), the adsorption coefficient of lambda-CHT and CPM decreased on both soils. This is mainly due to a competition between Cu and Pys for occupying the adsorption sites on soils. The information from this study have important implications for vineyard and orchard soils, which often contain elevated levels of Cu and Pys. These results are also useful in assessing the environmental fate and health effect of lambda-CHT and CPM. It is important for environmental scientists and engineers to get a better understanding of soil-metal-organic contaminant interactions. However, pesticide adsorption involves complex processes, and shortcomings in understanding them still restrict the ability to predict the fate and behavior of pesticide. Therefore, considerable research should be carried out to understand the mechanism of interaction between Pys and heavy metal on soils clearly.

Rhizospheric soil enzyme activity of allelopathic rice at seedling stage

In order to determine the relationship between allelopathic potential of rice and soil enzyme activity in rhizospheric soils, a dry cultivation experiment was conducted on enzyme activity in rhizospheric soil of allelopathic rice "PI312777", "IAC47" and "Iguape", and non-allelopathic rice "Lemont" at seedling stage. The results show that allelopathic rice inhibits dehydrogenase, peroxide, polyphenol oxidase, urease, and cellulose activity and enhances acid phosphatase, alkaline-phosphatase, invertase and catalase activity in rhizospheric soils. Correlation analyses show that urease and polyphenol oxidase activity is significantly negatively correlated with rice allelopathic potential, while acid phosphatase and alkaline-phosphatase activity is significantly positively correlated with rice allelopathic potential. No significant relationship exists between protease and dehydrogenase activity with other enzymes or microbial amount and rice allelopathic potiential. Allelopathic rice decreases polyphenol oxidase activity, increases acid-phosphatase, alkaline-phosphatase and invertase activity, which is beneficial for allelopathic substance accumulation, soil carbon and phosphorus cycle enhancement.

Activation of indigenous micorflora in oil-contaminated soils using photoluminescent films

A stimulating effect of sunlight transformed by a photoluminescent polymer film on the abundance dynamics and fermentation and respiration of indigenous microflora in oil-contaminated soils was investigated. Polymer film doped with photoluminophores based on inorganic Eu-complexes and common glasshouse film was used as a cover material for oil-contaminated soils at experimental and control sites. The application of photoluminescent film has been reported to stimulate a hundredfold growth of the microflora population, with the soil respiration intensity and catalase activity being increased by a factor of 2.5-3, respectively. The extents of biodegradation of petroleum hydrocarbons within 60 days were up to 70 and 30% of the overall background pollution level for the experimental and control site, respectively. Residual hydrocarbons extracted from samples of the contaminated soils were analyzed by infrared spectroscopy to show the appearance of additional absorption bands at 3350, 1600, and 1710 cm(-1), thus indicating the formation of metabolites during enzymatic oxidation of oil. Chromatographic data corroborated the occurrence of intense oxidation. The hydrocarbon biodegradation factor increases sixfold when the photoluminescent films are used.

Combined effect of cypermethrin and copper on catalase activity in soil

Pollution of soil environment has become a serious problem in many countries. Repeated application of bordeaux mixture and pyrethroids insecticides have led to elevated copper (Cu) and pyrethroids concentrations in vineyard surface soils. Therefore, it is recommended to evaluate the combined effect of copper and pyrethroids on soil enzymes. Our aim was to get a more comprehensive understanding of the effects of Cu and cypermethrin on the soil catalase, and to provide more information about the potential ecological risk of chemicals on the soil ecosystem. The dried and sieved soil sample was first thoroughly mixed with aqueous solution of CuSO4 5H2O, and acetone solution of cypermethrin according to the orthogonal design, and then incubated at 25°C for 35 days. Five concentration levels for each pollutant (Cu and cypermethrin) were studied. Control without any artificial contamination received the same amount of distilled water and acetone. Each test was conducted with three replications. Moisture in the incubated soil samples was kept at 60% of the full soil water holding capacity by weighing daily. Catalase activity was determined by back-titrating residual H2O2 with KMnO4 after 7, 14, 21, 28, and 35 days. Data treatment was essentially based on analysis of the variance test. During the incubation time, soil catalase activity was lower than the control samples and the result ranged from 70.64% to 100%, except for that of the two samples S6 and S13. The catalase activity in all samples was declined after application of Cu, without addition of cypermethrin. While the concentration of cypermethrin ranged from 0 to 150 mg kg–1, without the addition of Cu, the variety of catalase activity was as follows: restrained–activated–restrained. The combined effect of cypermethrin and Cu on soil catalase activity depends largely on the concentration of pollutants. The presumable explanation of the result that the catalase was inhibited by single Cu addition was due to: (1) complexation of the substrate, (2) combination with the protein-active groups of the enzymes, or (3) reaction with the enzyme–substrate complex. In our study, there were some differences in the catalase when soil samples were treated with a different concentration of cypermethrin. This is possibly related to the protect mechanism of soil catalase. In addition, the combined effect of cypermethrin and Cu on catalase activity is stronger than single cypermethrin, while weaker than single Cu. One of the possible explanations of this phenomenon is related with the interaction between cypermethrin and Cu. Another may be related to bioavailability. The combined effect of cypermethrin and Cu on soil catalase activity depends largely on the concentration of the pollutants. The magnitude and type of interaction may be strongly dependent on the level of response and the relative proportion of the components in the mixture. These factors should therefore be considered in risk assessments and in the setting of soil quality criteria. Generally speaking, the influence of pesticides and heavy metals on soil is a long-term process and is closely related to soil characteristics. Much more should be done to clearly understand the mechanism of interaction between cypermethrin and Cu on soil.

Enzyme activities of urban soils under different land use in the Shenzhen city, China

Urbanization has drastically changed soil properties, and an assessment of these changes is essential for soil management and soil health. The activities of urease, acid phosphatase, invertase and catalase, soil organic matter, pH, electrical conductivity (EC) and clay (&lt; 0.01 mm) content of urban soils under two land-uses in the central built-up area of the Shenzhen city were investigated, and multivariate analysis was used to study the relationship between soil enzymes and soil physical-chemical properties. The results showed that invertase activity in roadside soil was significantly higher than that in urban park soil, whereas catalase activity was significantly higher in urban park soil. Soil organic matter had significant positive correlation with activities of invertase, urease and acid phosphatase but not with catalase. Soil pH had a significant negative direct effect on urease and acid phosphatase activity, but the effect was counteracted by positive indirect effect of soil organic matter. Soil EC had a positive direct effect on activities of catalase and there was a significant correlation between soil EC and soil catalase activities. Soil organic matter, soil pH and EC were the major factors influencing activities of soil enzymes.

Effects of validamycin on some enzymatic activities in soil

There have been few investigations of the possible effects of validamycin on the enzymatic activities in soil. The objective of this present work was to study the short-term influence of enzymatic activity in validamycin treated soils. The results showed that high dose of validamycin introduced into soil had an significant effect on soil enzymatic activities, the degree of inhibition or promotion of enzymatic activities was not only related to the concentration of validamycin, but also to the remain time. Compared with the control (non treatment with validamycin), 240 ml.mg(-1) validamycin treatment caused a significant decrease (14%) of soil catalase activity; validamycin also inhibited urease activity to 67.3%, but subsequently, validamycin stimulated its activity higher than that of the control. Only the highest dose stimulated acid phophatase activities by 29.7%, and other concentration treatments had no effects on these enzymatic activities. The above results indicated that validamycin had effects on soil enzyme, but the effective time was short. It is also interesting to speculate that validamycin can be easily used by the soil microorganism as carbon source and energy.

Spatial patterns of soil microbial characteristics and soil moisture in a natural beech forest

To characterize the spatial heterogeneity of selected soil microbiological characteristics in relation to soil moisture content within a natural beech stand, we collected soil samples at 50 m intervals along a 1,500 m long transect in a beech primeval forest at Vtacnik mountains (Slovakia) from organic layers (OL and OF horizons) and the mineral A horizon (depth 0-10 cm) in July 2004 and June 2005. Gravimetric soil moisture, basal and substrate-induced respiration, respiration in situ and soil catalase activity were measured. Statistically significant differences in soil variables were found among horizons and partially among sampling dates. Soil microbial activity was closely correlated with soil moisture, especially in the OL horizon. No clear spatial autocorrelation of the assessed soil variables was found, but a significant correlation between years occurred. Moisture and microbial activity parameters were positively correlated with canopy openness in the A horizon, whereas no or negative correlations were observed in the overlying organic horizons.

Influence of selenium on oxidoreductive enzymes activity in soil and in plants

The aim of this greenhouse experiment was the assessment of the influence of H 2SeO 3 at soil concentrations of 0.05, 0.15 and 0.45 mmol kg −1, on the activity of selected oxidoreductive enzymes in wheat ( Triticum aestivum). The wheat plants were grown in 2 dm 3 pots filled with dust-silt black soil of pH 7.7. Applied H 2SeO 3 caused activation of plant nitrate reductase at all concentrations, but activation of plant polyphenol oxidase at only two lower concentrations. The highest concentration caused inhibition of polyphenol oxidase and peroxidase. Plant catalase activity decreased under the influence of 0.15 and 0.45 mmol kg −1 concentration. After the final analysis Se was quantified in plants and soil. The amounts in plants were: control (unamended soil) 1.95 mg kg −1; I dose (0.05 mmol kg −1) 18.27 mg kg −1; II dose (0.15 mmol kg −1) 33.20 mg kg −1 and III dose (0.45 mmol kg −1) 38.37 mg kg −1, in soil: 0.265 mg kg −1; 3.61 mg kg −1; 10.53 mg kg −1; 30.53 mg kg −1; respectively. Simultaneously, a laboratory experiment was performed, where the activity of soil catalase and peroxidase were tested after 1, 3, 7, 14, 28, 56, and 112 days after Se treatment. Peroxidase activity in soil decreased with increasing Se content, over the whole experiment. The lowest dose of Se caused activation a significant 10% increase in catalase activity, but the influence of others doses was unclear.

Effects of pesticides and their hydrolysates on catalase activity in soil.

Effects of pesticides and their hydrolysates on catalase activity in soil.

Influence of soil parameters on the effect of 3,4-dimethylpyrazole-phosphate as a nitrification inhibitor

Nitrification inhibitors specifically retard the oxidation of NH4+ to NO2– during the nitrification process in soil. In this study, the influence of soil properties on the nitrification-inhibiting effect of 3,4-dimethylpyrazole-phosphate (DMPP), a newly developed nitrification inhibitor, has been investigated. Based on short-term incubation experiments, where the degradation of DMPP could be largely disregarded, the oxidation of the applied NH4+ was more inhibited in sandy soils compared with loamy soils. The influence of soil parameters on the relative NO2– formation could be described by a multiple regression model including the sand fraction, soil H+ concentration and soil catalase activity (R2=0.62). Adsorption studies showed that the binding behaviour of DMPP was influenced markedly by soil textural properties, viz. the clay fraction (r2=0.61). The adsorption of DMPP was found to be an important factor for the inhibitory effect on NH4+ oxidation in a short-term incubation (r2=0.57). It is concluded that the evaluated soil properties can be used to predict the short-term inhibitory effect of DMPP in different soils. The significance of these results for long-term experiments under laboratory and field conditions needs further investigation.