Suelo Solonchak (Caracterizacion microbiologica)

Floor Solonchak ( Characterization microbiological )

Microbes in soil

1. Before sampling is necessary openness of the soil profile , for which a straight blade and a curved blade , to excavate and remove the roughly loose soil is required, and when compact or slightly hardened, also will require a pickaxe to loosen the soil .

2. Once the well done will require a pedological hammer, a spatula or knife stainless steel to mark the separation boundary and transition layers or horizons and facilitate the collection of the sample of each layer , together with the straight blade .

3. It also requires plastic bags with approximate capacity of 2 kg to deposit samples .

4. Other materials needed to be taken are: pedological backpack , labels , markers , notebooks , maps, plans and aerial photographs of the study area , camera or video, geoposicionador and field formats .

Soil sampling technique

• Purposeful sampling soil classification
• The soil is subdivided into strata and horizons that show the nature of its development. To study its attributes is necessary to obtain representative samples as possible, both to each sampling site and the area being studied.

procedure

The most important feature is the high concentration of soluble salts at shallow depth ( Salic horizon).

Solonchak into 4 subgroups of ground exist :

Solonetz : With high percentage of absorbed sodium ions in the exchange complex , specific alkaline soils.

Gipisoles : With a horizon of secondary enrichment plaster.

Durisols : nodes with a layer of material by silica cemented soil .

Calcisols : With enrichments of secondary carbonates .

A) Addition of substrate and electron acceptors .

Add , with a hypodermic syringe, to each tube with 9 mL of base culture medium , 0.2 ml of sterile citrate solutions of iron and 0.2 ml sodium acetate ; under sterile and anoxic ( purge syringe with nitrogen) conditions.

B ) Culture conditions .

Maintain the tubes at a controlled temperature of 30 ° C for 30 days.

C ) Analysis of results , indicative of iron reduction.

At the end of incubation time Porel determine the positive change in color tubes of the culture medium from yellow to colorless .

Is recommended controls sterile soil to prevent the formation of precipitates abiotic other , resulting from the presence of compounds in the soil as : Fe (OH) 3 , Mn (OH) 2 , etc.

Introduction

Characteristics of microbial activity in soils

• Microbial activity is limited by water ( drought , humidity) and nutrient status .
• Microbial activity is key in soil productivity .
• Microbes can be several hundred meters below the surface of the Earth
• Soil pH affect the development of microorganisms , the pH to extremely low proportion of bacteria decreases while climbing yeast .

• The term derives from the Russian solonchak words "sol " meaning salt and " chak " meaning salt area , hinting at their saline character
• They occur in areas where salt, such as coastal lagoons, lake beds or the lower parts of the valleys accumulates.
• Solonchaks are soils with a high content of soluble salts all or any part of the lagoon.
• They have a Salic horizon starting within 50 cm from the soil surface .
• They have a copper color characteristics .

Solonchak

The number and type of microorganisms in the soil depends on environmental factors such as :

Iron -reducing anaerobes

• The training process is due to the accumulation of soluble salts on the surface , or below the soil profile .
• They have a very limited ability to use only salt-tolerant plants.
• In coastal areas can appear in any climate.

Iron -reducing bacteria are a special class of microorganismocs using Fe oxides and hydroxides as electron acceptors , get energy from the reduction of Fe3 + to Fe2 + acoplad oxidation of organic pollutants and other metabolites to form CO2.