Soil Chemical Analysis

Impatti, adattamento e vulnerabilita Le cause e le responsabilita dei cambiamenti climatici sono state trattate sul numero di ottobre della rivista Cda. Approfondiamo l’argomento presentando il documento: “Cambiamenti climatici 2007: impatti, adattamento e vulnerabilita” votato ad aprile 2007 dal secondo gruppo di lavoro del Comitato Intergovernativo sui Cambiamenti Climatici (Intergovernmental Panel on Climate Change). Si tratta del secondo di tre documenti che compongono il quarto rapporto sui cambiamenti climatici.

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Climate Change 2007: Impacts, Adaptation and Vulnerability.

http://www.tinread.usarb.md:8888/tinread/fulltext/lal/soil_structure.pdf

Soil structure and management: a review

Framework Convention on Climate Change

Pathogenic microorganisms affecting plant health are a major and chronic threat to food production and ecosystem stability worldwide As agricultural production intensified over the past few decades, producers became more and more dependent on agrochemicals as a relatively reliable method of crop

Use of Plant Growth-Promoting Bacteria for Biocontrol of Plant Diseases: Principles, Mechanisms of Action, and Future Prospects

There is growing recognition for the need to develop sensitive indicators of soil quality that reflect the effects of land management on soil and assist land managers in promoting long-term sustainability of terrestrial ecosystems. Eleven soil enzymes assays were investigated relative to soil management and soil quality at two study sites. Soils were sampled from the Vegetable Crop Rotation Plots (VRP) (established in 1989 in humid western Oregon) which compared continuous fescue (Festuca arundinacea) and four winter cover crop treatments in annual rotation with a summer vegetable crop. The second site was the Residue Utilization Plots (RUP) (initiated in 1931 in semi-arid Eastern Oregon) which is under a winter wheat–summer fallow and compared inorganic N, green manure and beef manure treatments. Soil also was sampled at the research center from a nearby grass pasture that is on the same soil type. The enzymes were α- and β-glucosidase, α- and β-galactosidase, amidase, arylsulfatase, deaminase, fluorescein diacetate hydrolysis, invertase, cellulase and urease. At both sites there was a significant treatment effect for each enzyme tested (P<0.05). Enzyme activities (except α- and β-glucosidase and α- and β-galactosidase) were generally higher in continuous grass fields than in cultivated fields. In cultivated systems, activity was higher where cover crops or organic residues were added as compared to treatments without organic amendments. It was found that use of air-dried soil samples provided the same ranking of treatments by a number of enzyme assays and would facilitate adoption of these assays for practical or commercial applications. Deaminase was not a good indicator of soil quality, while β-glucosidase was suggested as an assay that reflects soil management effects and has microbial ecological significance because of its role in the C cycle.

Field management effects on soil enzyme activities

The need to understand the biological processes that are important for essential aquatic and terrestrial ecosystem function has prompted much research into the field of ecological enzymology. This book presents the two broad areas of application in a compilation of reviews by 21 international experts in their respective fields. The first explores enzymatic activities to assess the processes or mechanisms that operate in a given system, such as the rhizosphere, plant leaves and shoots, soil surfaces, and biofilms. The second considers enzymes or microbial cells as sensors to detect microbial activity and stresses due to pollution, management, or climatic change in both aquatic and terrestrial ecosystems.

Enzymes in the environment: activity, ecology, and applications.

With the increasing pressure to produce more food, fiber, and fuel to meet world demands on a limited land area, there is an unprecedented need to address global concerns about soil degradation. Understanding the underlying biological processes in tandem with identification of early warning indicators of ecosystem stress is needed to provide strategies and approaches for land resource managers and policymakers to promote long-term ecosystem sustainability. Biological and biochemically mediated processes in soils are fundamental to terrestrial ecosystem function. Ultimately, all members of the food web are dependent on the soil as a source of nutrients, and for degradation and cycling of complex organic compounds. Primary decomposers of organic matter provide energy that supports the activities of organisms from a number of trophic levels in soils. Historically, chemical and physical properties have been used as crude measures of soil productivity. Most notably, determination of soil organic matter has been related to general soil tilth. Soil organic matter changes very slowly, and therefore, many years may be required to measure changes resulting from perturbations. However, there is growing evidence that soil biological parameters may hold potential as early and sensitive indicators of soil ecological stress or restoration (Dick, 1992; Dick & Tabatabai, 1992). In Chapter 5 (this book) information is provided on soil quality in relation to soil microorganisms. In this chapter, soil enzyme activities will be discussed as a potential biochemical/biological indicator of soil quality.

Richard P. Dick

Papers

Field management effects on soil enzyme activities

Enzymes in the environment: activity, ecology, and applications.

Soil Enzyme Activities as Indicators of Soil Quality

A review: long-term effects of agricultural systems on soil biochemical and microbial parameters

Soil Enzyme Activities and Biodiversity Measurements as Integrative Microbiological Indicators