Project 4: How does organic component influence different Soil Properties?

Project 4: How does organic component influence different Soil Properties?

Organic material is very important to agriculture. Farmers and gardeners use it to increase the nutrients in their soil. Organic matter retain higher amount of water and in turn supply it to the plants on which they grow. Moreover organic matter may influence various soil properties like soil color, pH, organic-carbon content etc. So by studying soils containing different level of inherent organic material in your soil will provide a relative idea of water availability, soil colour,organic-carbon content, soil pH etc. Organic material also supply nutrients into soil and plants can take both water and nutrient from soil. This assist better plant growth.

Objectives:
1. To study variation of organic matter content of soils under different land use
2. To determine the water retention capacity of soils under different land use
3. To determine the colour, pH, organic-carbon content of soils under different land use

Materials Required:
Spade/ Khurpi, Colour chart, Wash bottle, Sieve set, Sample collection bags, Paper Tags/label
Soil test kit for Organic Carbon, Perforated container

Methodology:
1. Prepare a land use map of your locality
2. Collect representative surface (0-15 cm) soil sample from each land type and land use (for example, forest land, grass land, barren land, steep land, soil under agricultural crops, orchards, etc.). Air dry the samples, grind and pass through 2mm sieve for studying the following parameters.

Water holding capacity
1. Take 500g soil sample in perforated containers. Add the soil slowly followed by tapping so that soil of the container comes to natural compaction.
2. Place a plant saucer under each container to collect the leachate.
3. Pour measured volume of water from a measuring cylinder to each container and record the volume of water needed to completely saturate the column. Add approximately 100ml of water additionally to form a thin film of water over the soils of the container.
4. Wait for 12 hours
5. Measure the volume of water collected in the saucer,then substract this from total quantity of water added.
6. Repeat the experiment thrice for soils of each land type/use

Observations:

Mean value
WHC
Soil Colour
Soil pH
Organic Carbon
Soil Colour
Take table-spoon of soil and place into individual petri-dishes, or any similar glass or plastic containers. Be sure to label each dish appropriately. Now compare the colour of the soil with the Munshell colour chart (may be collected from Soil/Agriculture department) and note their dominant colours (red, brown, grey, yellow, yellowish red etc.). Moist the soil with few drops of water and record the moist colour also. Repeat the experiment thrice for soils of each land type/use.
Soil pH
Take tablespoon of soil and place into individual petri-dishes, or any similar glass or plastic containers. Be sure to label each dish properly. Wet each soil sample with 2 tablespoons of distilled water. Allow to sit for 3 to 5 minutes. Place one piece of pH paper on each soil sample. (Use pH paper with a range from at least 5-10). Determine the approximate pH or acid/base level of your soil. Repeat the experiment thrice for soils of each land type/use.

Soil Oxidizable Organic-Carbon (KIT METHOD)
Take 1 gram of soil in test tube. Add 2 ml of organic carbon reagent I ( 1N K2Cr2O7 ) and 2 ml of organic carbon reagent II ( conc. sulphuric acid) in the test tube. After 15 minutes stay determine the approximate Organic Carbon content of the soil under experiment from the colour chart matching. Repeat the experiment thrice for soils of each land type/use.

Colour Oxidizable organic Carbon,(%) Soil Quality
Dark green >0.75 High
Red 0.50 – 0.75 Medium
Orange < 0.50 Low

Results:
Water drained from the soil was measured exactly 12 hours after the water was initially added.
Then draw inference of the experiment

Relevance:
The study will throw light on the variation of water retention capacity, colour, pH,organic carbon content of soils under different land type and land use and gives an idea of importance of organic matter in controlling the availability of water, regulation of temperature due to colour, soil pH & organic carbon content thus nutrient availability for plant growth.

Suggested Additional Activities
1. Knowing water holding capacity of soil of the locality
2. Know your land – soil, water and land-scape relationship
3. Study of soil profile under different land use
4. Fluctuation of water tables in any season of the year of the locality/region
5. Distribution & quantification of water bodies for water use planning
6. Delineation and characterization of local watershed based on topography, drainage network and local knowledge
7. Distribution and mapping of important minerals of the region

Members:
Prof. S.S. Sahu, Prof. M.C. Talukdar, Dr. K. Das, Dr. M. De Roy, Mr. A. Chanak