Chemical & microbial analysis of

Farm Soil & Forest Soil

Milton Sarkar

What is soil ?• Soil is a heterogeneous mixture of silicate particles,

humus, and a variety of insoluble salts and oxides of metals called the solid phase, a liquid phase and a gaseous phase.

• Types of soil texture:1. Clayey2. Sandy3. Loamy

We performed soil analysis to…

• Analyze physiochemical parameters of soil.

• Analyze microbial parameters of soil.

• Study relationship between soil organic content and micro-organisms.

Every soil is a unique combination

of minerals, micro and macro

Organisms.

Also, soil is a/an:

Great integrator

Producer andabsorber of gases (CO2 and others)

Medium for plant growth

Medium of crop production

Home to organisms(plants, animals and micro-organisms)

Waste decomposer

Snapshot of geologic, climatic, biological, and human history

Source material for construction, medicine, art, etc.

Filter of water and wastes

Essential natural resource

Medium of heat andwater storage

Why we specifically chose forest and farm soil ?

• To analyze forest Biota:

- Forest is the richest biodiversity holder. - Forest is the source of timber & medicines to humans. We analyzed what

problems the trees may be facing in the forest and their solutions. - We searched for methods to maximize the growth of beneficial micro-organisms.

• To analyze farm fertility and types of organisms in it:

- Farm is the source of crops for us. Healthy soil gives rise to healthy crops. - Different organisms are favoured in various pH, chloride content, organic

content etc. Knowing this helped in identifying the useful organisms and provided methods of manipulation to favour these organisms.

- Earth worms are favoured in soil rich in organic content.

Characterization and Sampling Options

Soil Pit

Auger

Exposed Profile (road cut)

Surface Sample

Physical Analysis

Chemical Analysis

Microbiological Analysis

Interpretation of results• pH:

Soil chlorides

Total alkality

Total acidity

Total organic carbon

ConclusionChemical analysis:

• Farm soil. This soil is nearly ideal for growing leguminous plants. Currently, ground nut

is being grown at the site. Soil structure, pH, chloride content, sodium content, molybdenum content etc.

are all normal.Soil is falling short of organic matter. This is restricting growth of non-symbiotic

nitrogen fixing bacteria and earthworms.Organic matter need to be added along with liming, if necessary, to make it an

ideal soil.

• Forest soil. This soil is having high organic content. The pH is almost neutral. High

amount of organic acids is the reason. Nitrogen fixing bacteria may find it difficult to survive if the pH falls further.

Soil needs liming or extraction of excess organic matter.

Microbiological analysis:

• High organic matter was found in forest soil but farm soil was more workable ( aeration, water content, tillage etc.).

• Soils receiving well decomposed organic manures have better soil aggregates than those receiving saw dust and other types of not so easily decomposable organic wastes.

• Samples have been collected from two organic content rich soil regions like farm and forest. Forest soil is rich organic matter, 0.28 gm/ dry wt. whereas in farm soil, it is 0.12 gm/dry wt. Heterotrophic count on N. agar shows high population of bacteria & count on soil agar shows high population of nitrogen fixing & biodegrading bacteria.

• Moderate alkaline pH favours high population of actinomycetes in forest soil whereas comparative high population of fungal indices in forest may be due to high plant biodiversity at forest.

• The organic matter in soils is potential source of plant growth. Microbiological decomposition of organic matter is an essential step to release the bound nutrients in organic residues in an easily available form.

• We concluded that the number of actinomycetes increases in presence of decomposing organic matter.

References:Tabatabai, M. A. 1982. In Methods of Soil Analysis, Part 2. American Society of Agronomy and Soil Science Society of America, Madison, Wisconsin, USA.Doran, J. W. 1980. Soil microbial and biochemical changes associated with reduced till-age. Soil Sci. Soc. Nelson, D.W. & Sommers, L.E. Total carbon, organic carbon and organic matter.N. C. Braddy, Nature and Properties of Soil Science