|
Soil and leaf sampling
Soil samples may be collected during August-March period. Five to 20 spots (depending
on the total area to be sampled) are selected at random and 60 cm deep pits are
dug.
After removing the surface litter and mulch, a thin vertical section of soil is
cut from the top to a depth of 30 cm using a sharp edged tool such as chisel. Another
cut at a depth of 30 to 60 cm may be made and another thin section of soil may be
collected separately. Pool all samples of 0-30 cm depth and 30-60 cm depth separately.
If the composite sample is large, reduce the quantity by quartering. For quartering,
the well-mixed soil is spread into a polythene sheet or paper and divided into four
equal squares. The soil in the diagonally opposite squares is discarded and the
process is repeated until about 250-500 g of soil is obtained. The samples are dried
in shade, and packed in clean cloth bags.
Leaf Sampling
Leaf samples are collected during the period from August-October. During this period
leaves would be six to eight months old. Depending on the area to be sampled, 10
to 30 trees are selected at random (10 trees up to 5 ha, 30 trees for 20 ha and
proportionate number of trees for areas between 5 and 20 ha).
In the case of branched immature trees and trees under tapping, four basal leaves
are collected from the terminal whorl of low branches in shade from each of the
selected trees. In the case of unbranched young trees, plants without new flushes
are selected and four basal leaves from the topmost whorl are collected.
Leaflets are detached from the petiole using a sharp knife or blade. If 30 trees
are selected, only the middle leaflet from each leaf is taken. If 15, the two leaflets
on either side and if 10, all the three leaflets are collected. About 120 leaflets
should be available in one composite sample.
The leaf samples should be brought to the laboratory within 24 hours. If this is
not possible, the samples shall be packed and kept in refrigerator and brought on
the next day itself. Alternatively, each leaflet can be pressed on the upper side
with hot iron (at the cotton temperature range) and brought to the laboratory at
the earliest possible.
The proforma for submitting the case history sheet
of the sampled field
|
1
|
Name of the estate with address
|
|
2
|
Name of the block sampled and area
|
|
3
|
Sample No.
|
|
4
|
Depth of sampling 0-30 cm / 30-60 cm
|
|
5
|
Date of sampling
|
|
6
|
Planting material used and spacing
|
|
7
|
Age of the trees in the sampled area
|
|
8
|
Average girth of the trees in the sampled area (In the case of seedlings, the girth
at the height of 50 cm from the base; and for budded plants, the girth at 125 cm
from the bud union)
|
|
9
|
Elevation above mean sea level
|
|
10
|
Rainfall – average for the last five years
|
|
11
|
Slope – level/gentle/medium/steep
|
|
12
|
Cover crops
|
|
a. Pure (Pueraria, Calapogonium, Centrosema or Mucuna)
|
|
b. Mixture of legumes
|
|
c. Others
|
|
13
|
Previous history of the sampled area (Here state whether the area is a replanting
or new planting, previously cultivated or virgin area)
|
|
14
|
Manuring history (Here state the rubber mixture used specifying the various ingredients,
composition and quantity applied per tree or per ha for the past three years)
|
|
15
|
Time and method of application
|
|
16
|
Tapping system (1/2S d/2, 1/2S d/3 etc.) adopted with the average yield for the
past three years with initial tapping height
|
|
17
|
Whether the sampled field of rubber is mixed with coconut, arecanut or inter-cultivated
with tapioca, banana etc.
|
|
18
|
Stand per ha
|
|
19
|
Protective measures adopted against diseases
|
|
20
|
Whether stimulants are used, if so, give details
|
|
21
|
Leaf retention (visual grading) – good/average/poor
|
|
22
|
Signature with place and date
|
|