Soil Enzyme Activities as Biological Indicators of Soil Health (original) (raw)
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Soil Enzymes as Bioindicators of Soil Ecosystem Status
Applied Ecology and Environmental Research, 2015
A variety of methods were developed to measure soil biological activity. All these methods are not suited to produce generally accepted results, but they give relative information about the ecological status of soil. Soil enzymatic activity assays is only one way to measure the ecosystem status of soils. The technique is quite simple and produces reproducible results, and is nowadays of practical importance because the influence of agro-chemicals, industrial waste, heavy metals, as well as soil fertility management can be measured. Especially the search for urease inhibitor is of particular interest in order to reduce ammonia losses from soils. Soil enzymes have been reported as useful soil quality indicators due to their relationship to soil biology, being operationally practical, sensitive, integrative, ease to measure and described as "biological fingerprints" of past soil management, and relate to soil tillage and structure. The focus of this article is to provide a review of soil enzyme activity as a biological, process-level indicator for impacts of natural and anthropogenic activities on soils. This knowledge of soil enzymology can be applicable as bioindicator to human endeavour of ecosystem perturbation, agricultural practices and xenobiotic pollution.
A Review on the Enzymatic Indicators for Monitoring Soil Quality
2017
Soil is a dynamic, living, natural system that is vital to the function of terrestrial ecosystems. Soil health is maintained by physical, chemical and biological factors. Physical factors include bulk density and soil porosity, indicators of soil compaction. Chemical factors (soil pH, inorganic nitrogen, available minerals and organic carbon content) provide information for the balance of soil solution and exchange sites. Biological and biochemical factors like microbial biomass, soil respiration, potentially mineralised nitrogen and activity of soil enzymes indicate the soil’s ability to function or recover from disturbance such as climate change, pest infestation, pollution and human exploitation in agriculture. The enzymes play an important role in the decomposition and recycling of nutrients from dead plants and animal tissues, the fixation of nitrogen, the maintenance of soil structure and the inhibiting effects of pollutants. Therefore, the activity of soil enzymes can be used...
Potentials for Soil Enzyme as Indicators of Ecological Management
Activity measurements of selected soil enzymes (cellulase, glucosidase, amidohydrolase, phosphatase, arylsulfatase) involved in carbon, nitrogen, phosphorus, and sulfur cycling in the biosphere, hold potential as early and sensitive indicators of soil ecological stress and restoration, These measurements are advantageous because the procedures are simple, rapid, and reproducible over time. Enzyme activities are sensitive to short-term changes in soil and kind-use management. Enzyme activities have also been observed to be closely related to soil organic matter proposed as an index of soil quality.
Soil Enzymes – Valuable Indicators of Soil Fertility and Environmental Impacts
Bulletin UASVM Horticulture, 66(2)/2009
Soil enzymes are known since long time. A lot of older publications demonstrate the importance of exogenous soil enzymes for nutrient cycling in soils and the fertility of soils. The latter plays an extraordinary role in sustainable agriculture. Therefore indicators are needed which can be used for controlling. In our experiments with different organic amendments (green manure, straw and composts) used to improve and keep soil fertility different influences on soil enzymatic activities could be demonstrated. Fertility level was tried to characterize with - and -glucosidase, alkaline phosphatase, and urease activity. Generally could be proven that the different amendments have significant influence on the different enzymes in time and spatial distribution. Especially heavy metals in soil solution have a strong impact on soil enzyme activity. The variation of enzyme activity during time depends on the specific enzyme under consideration and the soil habitat. Activity follows also a strong gradient with soil depths. For comparative studies it is recommended to test only the upper soil layers up to a depth of 10 cm.
Application of soil enzyme activity test kit in a field experiment
Soil Biology and Biochemistry, 2001
We developed a test kit utilizing¯uorogenic substrate analogues for the measurement of several enzyme activities in soil samples. Our hypothesis was that the pattern of different enzyme activities re¯ects changes in microbial structure and activity in a more sensitive way than total microbial biomass or activities of individual enzymes. In the test kit activities of 11 soil enzymes were measured simultaneously from diluted soil slurries on multiwell plates. After incubation for 3 h the¯uorescence was measured quantitatively using an automated plate reader. The test kit was evaluated in a ®eld experiment designed to investigate various management practices. During the years 1981±1993 the experimental ®eld was divided into four sites. One of the plots received full mineral fertilization on the basis of chemical soil analysis, another received 50% of the recommended mineral fertilization, the third plot received green manure (harvested crop residues) and the fourth plot received composted crop residues. Since 1994 the sampling area included sites in a transitional stage to organic cultivation and the minerally fertilized site. Season, crop plant and management practice all gave rise to differences in the enzyme activity pro®le. Thē uorogenic analysis was sensitive and allowed quanti®cation of all the enzyme activities in all the samples. When four replicate measurements were used the standard deviation was usually less than 10%, depending on the enzyme.
Kinetics of soil enzyme activities under different ecosystems: An index of soil quality
Soil microbial activity plays an important role in regulating biotransformation, nutrient cycling and hence the microbiological processes are at the center of many ecological functions. The kinetic parameters (Vmax and Km Michaelis constant) of different enzymes (amylase, invertase, protease, urease, and dehydrogenase) were determined in order to assess the metabolic response of soil. The maximum reaction velocity (Vmax) represents a maximum rate of activity when all enzymes are saturated, which markedly increased in forest soil as compared to fresh mine spoil due to the gradual accumulation of soil organic matter. Smaller Km value was estimated in forest soil (FS) as compared to fresh mine spoil (FMS), suggesting the greater affinity of soil enzymes for substrate in FS. The catalytic efficiency (Vmax/Km) reflects an impression on microbial community composition with a change in soil enzymes. These enzyme characters (activities and kinetic parameters) have greater significance as early and sensitive indicators of the changes in soil properties induced by different management systems. These parameters (Vmax and Km) can be useful markers to assess changes in microbial activity of soil, since they represent quantity and affinity of enzymes respectively. The metabolic index (dehydrogenase activity/organic carbon (OC)) was found to be correlated with Vmax of dehydrogenase (r = 0.953; p < 0.01) and OC (r = 0.880; p < 0.01). Principal component analysis was able to discriminate seven different soil samples into seven independent clusters based on their enzyme activities and kinetic parameters. Indeed, the study revealed the importance of kinetics study of soil enzymes, which can be considered valid parameters to monitor the evolution of microbiological activity in soil, and hence an index of soil quality.
SOIL ENZYMES AND CHARACTERISTICS
For understanding the structure and the functions of soil ecosystem, the analysis of soil microorganisms’ population and the factors affecting their activities are important. For this purpose, the soil enzymes: are used as indicators of soil fertility and microbial activity. The distribution of soil enzymes and activities on the agricultural lands under the monoculture or sowing is accepted as a wide research subject however the researches which investigate the ecological relation in natural ecosystem by using the enzymes on biotope characterization are rare or not too much. With this study it was attempted to establish a base for future studies by evaluating the done researches on soil properties and their effects on soil fertility.
Soil Biology and Biochemistry, 2008
There is growing interest in the applications of soil enzymes as early indicators of soil quality change under contrasting agricultural management practices. However, despite there being an abundant literature on this subject, most comparative assessments have been based on a limited number of experimental farms and, therefore, conclusions are not as robust as desired. In this study, we compare 18 pairs of organic and neighbouring conventional olive orchards in southern Spain. These sites were selected to allow the definition of the relative contributions of site-landscape features, soil type, and time since organic accreditation and tillage intensity, on the soil quality. Soils were analysed for physico-chemical properties, the activities of dehydrogenase, b-glucosidase, arylsulphatase, acid and alkaline phosphatase, and potential nitrification. The geometric mean of the assayed enzymes (GMea) was validated with an independently performed Principal Component Analysis (PCA), and used as a combined soil quality index. The effects of tillage intensity and time since organic accreditation on the improvement of soil quality were also evaluated within the subset of organic farms. Overall for the 18 sites, contrasted management practices did not differ in their impact on basic soil physico-chemical properties, except for loss of on ignition and available inorganic N which were higher and lower in organic farms, respectively. Organic management resulted in significantly higher soil enzyme activities. However, differences were not significant in some of the paired comparisons when considered individually. This highlights the need for extensive comparative assessment, as in this study, to draw clear conclusions concerning the changes to soil quality under sustainable management practices. The GMea was significantly correlated with the first axis of the PCA and shown to be appropriate for condensing the set of soil enzyme values to a sole numerical value. Soil quality changes in organic versus conventional farms, as measured by the GMea, ranged from À23% to 97%, and was highly dependent on time since organic accreditation (r ¼ 0.88; P < 0.01). On the other hand, tillage intensity clearly tended to delay any progress in soil quality in the organic farms.
Relationships Between Enzyme Activities and Microbial Growth and Activity Indices in Soil1
Soil Science Society of America Journal, 1983
Soil enzyme activities are often used as indices of microbial growth and activity in soils. Quantitative information concerning which soil enzymes most accurately reflect microbial growth and activity is lacking. Relationships between the activities of 11 soil enzymes and microbial respiration, biomass, viable plate counts, and soil properties were determined in surface samples of 10 diverse soils. Correlation analyses showed that alkaline phosphatase, amidase, a-glucosidase, and dehydrogenase activities were significantly (P < 0.01) related to microbial respiration as measured by CO 2 evolution in soils which had received glucose amendments. Phosphodiesterase, arylsulfatase, invertase, a-galactosidase, and catalase activities were correlated at the 5% level while acid phosphatase and urease activities were not significantly correlated to microbial respiration. There was no significant correlation between the 11 soil enzymes assayed and CO 2 evolution in the 10 unamended soils. Only phosphodiesterase and a-galactosidase activities were significantly (P < 0.05) related to microbial numbers obtained on some selective culture media. Alkaline phosphatase, amidase, and catalase were highly correlated (P < 0.01) with microbial biomass as determined by CO 2