Mechanical harvesting

What it is

Mechanical harvesting works on geometry rather than judgement. A reciprocating or rotary cutter is run across the plucking table at a fixed height, and everything above that line is severed and carried into a bag by an air stream. The consequence is that the intake contains ready shoots, unready shoots, mature leaf and stem in whatever proportion the field happened to hold, so the sorting that a plucker does in the field has to be done later by machine or not at all. Against that, it collapses the labour requirement of the single most labour-intensive operation in tea, which is why it dominates in Japan, in Argentina, in much of Africa and in Chinese commodity production.

Also transliterated as: kikai tekisai, ji xie cai zhai.

What it does to the leaf

Severs the upper canopy at a fixed cutting height and conveys the cut material away, harvesting ready and unready shoots together.

What it does to the cup

Raises the proportion of coarse leaf and stem in the cup, which reads as a flatter, woodier and less aromatic liquor unless the field is managed to make the canopy uniform.

Variants that matter

Ways this step is carried out that produce genuinely different results, rather than regional names for the same thing.

Two-person hedge harvester

A flexible cutter bar carried by two operators along a row, with a fan blowing the cut leaf into a shared bag. The most widespread powered format.

Ride-on and rail-guided harvesters

Standard on flat, precisely spaced Japanese fields, where rows are laid out from the start to suit the machine rather than the machine adapted to the field.

Selective harvesters

Machines that attempt to grade by shoot tenderness or height as they cut. They narrow the gap and have not closed it.

Other steps at the Plucking stage

• Fresh-leaf reception and grading — The decision, taken at the factory door, about which intake becomes which product — and the point at which a day's leaf is split into separate lots that never meet again.
• Fresh-leaf transport and holding — The hours between the bush and the factory door, during which a packed bag of leaf can heat itself and start changing before anybody has decided what it should become.
• Hand plucking — Picking each shoot individually by hand, which is the only method that can choose what to take and what to leave.
• Leaf separation by hand (ban pian) — Breaking each freshly picked shoot apart by hand so that the individual leaves go forward and the bud and the stem are set aside.
• Plucking standard — The rule about how much of each shoot is taken — bud only, bud and one leaf, bud and two, or mature leaf — which is set before any factory decision is made.
• Shading — Covering the bushes for days or weeks before plucking, which changes the leaf’s composition before it is ever picked.

Teas that go through this step

• Argentine black tea
• Atherton Tablelands tea
• Burundian black tea
• Cameron Highlands black tea
• Cameroonian black tea
• Charleston black tea
• Jhapa CTC
• Mambilla tea
• Mozambican black tea
• Ugandan black tea
• Wahgi valley tea
• Wush Wush tea
• Zimbabwean black tea

Guides covering this step

• The plucking table, and the cycle that runs on it — The flat green surface across a tea field is an engineered object. Its height, density and evenness determine how the field is harvested, how often, by whom, and what proportion of what is picked is worth having.
• The bud, and why “one bud two leaves” is a botanical statement — Every plucking standard in tea is a sentence about where on a growing shoot the picker stopped. The reason the position matters is that a shoot is not uniform: it has a gradient running down it, and the standard is a decision about how far into that gradient to reach.
• How many plants in a hectare, and what that decides — The spacing of a tea field is decided once, before anything is planted, and it constrains the next fifty years — the yield curve, whether a machine can ever be used, how the soil behaves, and how much of the crop a person can pick in a day.