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RUBBER
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.
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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
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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 |
Last updated: 24-05-2008
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