EXP 401- On farm Advisory for Soil Health, Water Quality and Plant Nutrition.PPT.pptx
1. TAMIL NADU AGRICULTURAL UNIVERSITY
AGRICULTURAL COLLEGE AND RESEARCH INSTITUTE
VAZHAVACHANUR , THIRUVANNAMALAI - 606753
EXP 401- ON FARM ADVISORY FOR SOIL
HEALTH, WATER QUALITY AND PLANT
NUTRITION
COURSE TEACHER BY:
Dr.N.SENTHILKUMAR
ASSOCIATIVE PROFESSOR (SS&AC)
2. collection of soil samples & collection and processing
of soil samples forlaboratory analysis
3. Principle
Soil testing aims to analyze and classify
soil, and guide fertilizer use for optimal
crop production. Accurate sampling is key,
requiring representative samples taken at
regular intervals (1 per 2–5 hectares).
Proper mixing and sub-sampling ensure
reliability. Sampling from soil profiles
represents the broader area in surveys.
4. Materials
required
1. Spade or auger (screw or tube or post hole
type)
2. Khurpi
3. Core sampler
4. Sampling bags
5. Plastic tray or bucket
5. Collection of
soil samples
• The soil sample collected should be representative of the
area sampled. A field can be treated as a single sampling
unit if it is uniform in all respects. Variation in slope,
texture, color, crop(s) growth and management levels
should be taken into account for soil sampling.
• Separate sets of composite samples need to be collected
from areas differing in these characteristics. Recently
fertilized plots, bunds, channels, marshy tracts, area near
trees, farm ways, buildings, wells, compost piles or other
non-representative locations must be avoided during
sampling.
• When crops are grown in rows, samples can be taken in
between the rows. Soil samples should be taken in zig zag
pattern or randomly.
7. PROCEDURE
Divide the field into different homogenous units based on the visual observation and farmer’s experience and select the sampling spots.
Remove the surface litter at the sampling spot.
Drive the auger to a plough depth of 15 cm and draw the soil sample.
Collect at least 10 to 15 samples from each sampling unit and place in a bucket or tray.
If auger is not available, make a ‘V’ shaped cut to a depth of 15 cm in the sampling spot using spade.
Remove thick slices of soil from top to bottom of exposed face of the ‘V’ shaped cut and place in a clean container.
8. • Mix the samples thoroughly and remove foreign materials like
roots, stones, pebbles and gravels.
• Reduce the bulk to one kilogram by quartering or
compartmentalization.
• Quartering is done by dividing the thoroughly mixed sample into
four equal parts. The two opposite quarters are discarded and the
remaining two quarters are remixed and the process repeated until
the desired sample size is obtained.
• Compartmentalization is done by uniformly spreading the soil
over a clean hard surface and dividing into smaller compartments
by drawing lines along and across the length and breadth. From
each compartment a pinch of soil is collected. This process is
repeated till the desired quantity of sample is obtained.
9. • Collect the sample in a clean cloth or polythene
bag.
• Avoid sending soil samples in fertilizer bags.
• Label the bag with information like name of
the farmer, location of the farm, survey No.,
previous crop grown, present crop, crop to be
grown in the next season, date of collection,
name of the sampler etc.
10. Processing and storage
• Assign the sample number and enter it in the laboratory soil sample register.
• Dry the sample collected from the field in shade by spreading on a clean
sheet of paper after breaking the large lumps, if present.
• Spread the soil on a paper or polythene sheet on a hard surface and powder
the sample by breaking the clods to its ultimate soil particles using a wooden
mallet.
• Sieve the soil material through 2 mm sieve.
• Repeat powdering and sieving until only materials of >2mm (no soil or clod)
are left on the sieve.
• Collect the material passing through the sieve and store in a clean glass or
plastic container or polythene bag with proper labeling for laboratory
analysis.
• For the determination of organic matter it is desirable to grind a
representative sub sample and sieve it through 0.2 mm sieve.
11. If the samples are meant for the analysis of
micronutrient utmost care is needed in
handling the sample to avoid contamination of
iron, zinc and copper. Brass sieves should be
avoided and it is better to use stainless steel or
polythene materials for collection, processing
and storage of such samples.
Air-drying of soils must be avoided if the
samples are to be analyzed for NO3-N and
NH4-N as well as for bacterial count.
