Land Selection for Tea

Tea is economically cultivated in a wide range of soils. In tropical, sub-tropical and temperate climatic conditions, tea grows in soils derived from Gneiss or Granites, Flat Alluvial lands, Peat Soils, Volcanic Ashes and Residual Formations.

Albizia moluccanais the best indicator plant that shows the suitability of a soil for the cultivation of tea, especially  in South-East Asian region, i.e. countries like India and Sri Lanka, etc. Tea is a plant that love to grow in acidic soils. It is considered that it can grow in a range of pH 4 - 6.5, where the optimum range is pH 4.5 - 5.5. If the pH of the soil is out of that optimum level, it should be corrected with Aluminum Sulphate or elemental Sulphate, before the planting. Lands naturally grown with Bracken fern (Gleichenia linearis), generally known as in this optimum pH range. Red-Yellow Podzolic Soils (RYP) is the best tea growing soil. These are the dominant soils in the low country and upcountry wet zone in Sri Lanka.

Albizia moluccana Leaves & Flowers

Gleichenia linearis Plant

If you are planning to replant old tea cultivation, it is always better to select lower “B” category and upper “C” category fields for that. Generally, tea estates have categorized their tea fields as A, B & C based on the yield (kg/ha/yr) over a period of not less than 2-3 years. Highest yielding lands come under category “A” while lowest in “C”.

The lands selecting must be undulating terrains, well drained and with a good soil depth and un-eroded. It is always advisable to avoid eroded lands with slab rock, concentrated boulders, surface rocks and gravel. In Sri Lankan conditions well drained lands less than 70% (31.5^o) of slope (Mid elevations 55% of slope or 24.75^o), more than 60 cm of soil depth, less than 20% of surface rockiness and less than 50% of gravel in top 90 cm layer of soil are considered as generally accepted parameters in land selection for ea cultivation. Flat lands adjoining paddy fields, water bodies or boggy areas are advisable to avoid due to poor drainage and soil aeration.

Land slope can be easily measured (either in percentage or degrees) with Clinometers. Otherwise, it could be simply measured with a rope. One end of the rope is wedge to the slope while a person below to that point raise the other end so that the rope would remain in the horizontal pane. Vertical height to the hand of the man at the point which the rope is held (A) divided by the horizontal length of the rope from the wedge to man’s hand (B), multiplied with 100 will give you the slope in percentage.

Simple way of finding Land Slope in percentage

Simple Home-made Clinometer, its Mechanism, Pocket Clinometer and Hand-held Clinometer in use

Soil depth is measured after preparing soil pits. Number of soil pits dig will be depended on the variation of the land. But generally, there should be at least 12 – 15 soil pits made to cover a one hectare land. The soil pit is 1 m X 1 m X 1 m in dimension and one wall should directly face the sunlight. Soil depth is measured with the meter tape from the upper brim of the pit to the parent rock. Apart from the soil depth, we can inspect for any hard layers underneath the soil surface, type & structure of the soil, depth of the gravel layer, depth of the top soil layer, soil color, etc. in the same location. At least 60 cm of soil depth is considered compulsory for commercial tea cultivation while 60 cm – 90 cm is moderately suitable and more than 90 cm will be the optimal.   

Duly Prepared Soil Pit for Inspection

In determining gravel percentage, take samples from the top 90 cm layer of the soil pit. Air-dry the sample and carefully break any soil aggregations with hand and weigh (Initial weight) it. Then sieve it through 10 mm mesh & collect what is remained in the sieve and weigh (Weight of Gravel). The following equation gives the percentage gravel content.

Set of Siever for partical size analysis

Surface rockiness is measured visually. Visually inspect the land from a distance and determine how much surface area covered with rocks and approximate percentage of that.

Avoid steep rocky clayey or gravelly patches even in a good land you have selected. Such bad patches of land can be easily identified by the growth of rehabilitation grass (Guatemala & Mana). If rehabilitation grass noticed retarding or wilting like symptoms, such land pockets may be having some kind or limitation for tea as well. Therefore, use such areas continue with grass as thatch banks, or diversify them into fuel or timber crops, rather than cultivating tea.

Apart from above discussed land and soil parameters, climatic factors such as rainfall & its distribution, prolonged drought conditions, desiccating wind areas should be avoided from tea cultivation. In Sri Lanka, only wet and intermediate zones could be cultivated with tea. The Agro Ecological Regions (AER,) suitable for tea cultivation, are as follows. (W – Wet zone, I – Intermediate zone, U – Up Country, M – Mid Country, L – Low Country)

• Wet zone -                    WU1, WU2a, WU2b, WU3

WM1a, WM1b, WM2a, WM2b, WM3a, WM3b

WL1a, WL2a

• Intermediate Zone -       IU1, IU2, IU3a, IU3b, IU3c, IU3d, IU3e

IM1a, IM2a, IM2b, IM3c