Mechanical potato harvesting is the single largest productivity improvement available to Korean highland potato operations still using predominantly manual digging. The labour required to manually dig 1 hectare of potatoes in Gangwon-do highland conditions — typically 25–40 person-hours per hectare depending on yield and stone content — can be replaced by 1.5–3 tractor-hours of mechanical digger operation. For farms operating in a planting-to-harvest window already constrained by altitude and frost calendar, the time saving from mechanical harvest is as important as the labour saving.
The Watanabe EP-AWB potato digger series covers four configurations from the 2-row mounted EP-AWB-1600 through to the 4-row trailed EP-AWB-3200 and the in-field packaging EP-CWB-2L Big Bag Harvester. Each configuration has a specific application range — farm scale, field geometry, row count, and supply chain destination all influence which configuration delivers the best result for a specific Korean operation. Buying the wrong configuration means buying a machine that underperforms relative to your actual operational requirements, even if the specifications appear comparable on paper.
This guide explains how the Watanabe potato digger range is structured, what determines the right configuration for different Korean highland operations, and how to match your row spacing — set at the PSW-3200 rotavator stage — to the digger that harvests it efficiently six months later.
The Core Decision — Mounted or Trailed, and Why It Matters
The fundamental difference between mounted and trailed potato digger configurations is where the harvested potato goes after the lifting and separation process:
Mounted digger (EP-AWB-1600): The machine mounts on the tractor’s rear three-point hitch. After the vibrating web separator removes soil from the lifted potatoes, the clean tubers are directed to one of three discharge options — side windrow (Kit A), rear elevator to following collection cart (Kit B), or transfer elevator to trailer (Kit C). The tractor, digger, and output system move as a single unit through the field. This configuration is compact, manoeuvrable in shorter field lengths, and suited to smaller operations where a dedicated following cart or truck is not always available.
Trailed digger (EP-AWB Trailed series, EP-AWB-3200): The machine is towed behind the tractor on its own wheels. Trailed configurations are typically higher-capacity — the EP-AWB-3200 harvests 4 rows simultaneously — and may include integrated bunker or tank capacity that allows the machine to operate independently for longer periods before requiring a discharge stop. Trailed diggers are suited to larger fields where the higher initial capital cost is justified by throughput gains, and where field geometry allows the wider turning radius of a tractor-plus-trailer combination at headlands.
| Factor | Mounted (EP-AWB-1600) | Trailed (EP-AWB-3200) |
|---|---|---|
| Rows harvested | 2 rows | 4 rows |
| Min. tractor HP | 75 HP | 110+ HP |
| Linkage | Cat. 2 (rear hitch) | Drawbar tow |
| Headland turning | Tight — suitable for short rows | Wider radius — needs longer rows |
| Terrain flexibility | High — slopes, narrow terraces | Lower — flatter, larger fields |
| Daily coverage | 0.5–1.2 ha/h (2-row) | 1.0–2.0 ha/h (4-row) |
| Best scale | 2–15 ha operations | 15+ ha operations |
EP-AWB-1600 Mounted Potato Digger — The Korean Highland Standard
The EP-AWB-1600 potato digger is a 2-row mounted implement (Cat. 2 three-point hitch, 75 HP minimum PTO) — the standard configuration for Korean highland potato farms in the 2–15 ha operational scale range. Its adoption by the majority of Korean commercial highland potato operations reflects several practical advantages that align with the specific field conditions and farm logistics of Gangwon-do potato country:
How the EP-AWB-1600 Works
The machine’s two lifting shares travel beneath the two planted rows, angled to penetrate below the tuber zone at 15–20 cm depth. As the tractor advances, the shares lift the complete ridge — soil, tubers, and any residual surface material — onto the vibrating web conveyor above. The web conveyor’s reciprocating motion separates loose soil and small particles (which fall through the web and back to the field) from the tubers (which are too large to fall through the web mesh and ride forward along the conveyor). By the time the tubers reach the rear of the conveyor, the majority of adhering soil has been separated by vibration — producing clean, soil-free tubers ready for discharge.
The vibrating web separation is the critical quality step: tubers with excessive adhering soil at harvest create problems at grading and packaging, and in long-term storage, soil pockets between tubers promote moisture accumulation and disease spread. The web’s vibration rate and amplitude determine the completeness of soil separation — optimised for the specific soil density and moisture conditions of Korean highland granite-derived soils.
Three Output Kits — Matching Harvest Logistics
The EP-AWB-1600 is available with three different output configuration kits, each suited to a different harvest logistics approach:
Kit A — Side Windrow
Tubers are deposited in a side windrow alongside the harvested row. Manual picking from the windrow follows the digger pass. This is the lowest-cost output configuration — no additional collection equipment required — and is suited to small family operations where manual labour is available for the picking step. Not suited to operations above approximately 2–3 ha where manual windrow picking creates a labour bottleneck at the harvest timing peak.
Kit B — Rear Elevator to Cart
A rear elevator transfers clean tubers from the web separator discharge into a collection cart or bin trailer following directly behind the digger. The operator drives the tractor (with digger) forward; the cart follows automatically on its own wheels behind. When the cart is full, it is exchanged for an empty one — eliminating the windrow picking step entirely. This is the dominant configuration for Gangwon-do commercial potato operations in the 5–15 ha range where mechanical harvest without manual picking is the goal.
Kit C — Transfer Elevator to Trailer
A lateral transfer elevator moves tubers from the digger directly into a trailer running alongside (rather than behind) the digger. Suited to fields and tractors where a following-behind cart is not possible due to field width or headland constraints. Less common in Korean highland conditions than Kit B due to the requirement for a parallel-running trailer, but used on specific wide-terrace field geometries in North Gyeongsang and South Gyeonggi potato production zones.
Korean recommendation: For commercial operations above 5 ha targeting mechanical harvest with minimal manual labour, Kit B (rear elevator to cart) is the configuration that eliminates the manual windrow picking step while remaining compatible with Korean highland field geometries and tractor logistics. Kit A remains practical for operations below 2–3 ha where labour cost is managed through family farm structure rather than mechanization. Kit C is selected for specific field configurations where Kit B’s following-cart geometry is constrained.
Why Row Spacing Matching Is Non-Negotiable
The EP-AWB-1600’s two lifting shares must travel beneath the tuber zone of two adjacent planted rows. The share spacing — the horizontal distance between the centrelines of the two lifting shares — must match the planted row spacing exactly. If the share centres and the planted row centres do not coincide, the shares travel partly beneath tubers rather than entirely below them: shares cut through the tuber zone, damaging tubers directly, increasing cull rates, and reducing revenue.
The planted row spacing is set by the PSW-3200 रोटावेटर working width at tillage (Step 2 in the 7-step potato system), maintained through the furrower (Step 3), planter (Step 5), and cultivator (Step 6) — and must be confirmed before purchasing the digger. Confirm your planted row spacing measurement from the field before specifying the EP-AWB-1600 share spacing. A 5 cm mismatch between planned and actual planted spacing is common enough in Korean highland operations that field measurement is essential — do not order based on nominal system specifications alone.
EP-AWB Trailed Series and EP-AWB-3200 — For Larger Operations
The EP-AWB trailed digger series and the EP-AWB-3200 (4-row trailed) are suited to Korean potato operations above approximately 15 hectares annual harvest area, where the EP-AWB-1600’s 2-row throughput — typically 0.5–1.2 ha per hour depending on field length and logistics — creates a harvest timing constraint relative to the crop’s optimal harvest window.
Why Throughput Matters in Korean Highland Conditions
Korean highland potato harvest timing is constrained by two overlapping factors: the crop’s physiological harvest maturity window (typically 80–100 days after emergence, variety-dependent), and the weather window at harvest altitude. In Gangwon-do at 600–800 m elevation, the period between optimal harvest maturity and the arrival of autumn rains that make field access difficult for heavy machines is often 3–4 weeks. For an operation with 25 hectares of potato, harvesting at 1.0 ha/hour of productive digger time requires 25 hours of digger operation — achievable in 4–5 good-weather days with a 2-row mounted digger. If weather delays compress this window to 2–3 days, the 2-row digger cannot complete the harvest before deteriorating conditions close the field.
The EP-AWB-3200 (4-row trailed) harvests at approximately double the row coverage rate of the EP-AWB-1600 in comparable conditions — 1.0–2.0 ha per hour versus 0.5–1.2 ha per hour. For a 25-hectare operation, this doubles the harvest rate and halves the number of weather-window days required to complete the harvest. For operations above 20–25 hectares where weather-window risk is a meaningful production risk factor, the throughput advantage of the 4-row trailed configuration is a genuine risk management investment, not only a productivity improvement.
Field and Terrain Requirements for Trailed Configurations
The trailed digger configurations have different field requirements from the mounted EP-AWB-1600 that are important to assess before selecting a trailed configuration for a Korean highland operation:
Row length: Trailed diggers require longer minimum row lengths than mounted diggers because the tractor-plus-trailer combination requires more headland space at row ends for turning. As a practical guideline, rows below approximately 80–100 m length make the headland turning frequency of a trailed digger disproportionately high relative to productive harvest time — the tractor spends an excessive fraction of its operating time turning rather than harvesting. For field sections with short rows, the mounted EP-AWB-1600 is more efficient despite its lower theoretical throughput. Korean highland potato fields with their characteristic terraced geometry and irregular lengths often have sections where the mounted digger is more appropriate even on operations large enough to justify a trailed machine.
Field slope: Trailed configurations are more sensitive to cross-slope and down-slope gradients than mounted configurations. A mounted digger pivots on the tractor’s rear hitch and can follow contour variation more flexibly than a trailed implement on its own fixed wheels. For Korean highland fields with slopes above 15% — common in the terrace sections of Hoengseong-gun and Jeongseon-gun — the mounted EP-AWB-1600 tracks field contour more reliably than trailed configurations at equivalent slopes. Large Korean potato operations with mixed field geometry — some flat, some sloped — often operate both a 2-row mounted and a 4-row trailed digger, assigning each to the field sections it handles most efficiently.
EP-CWB-2L Big Bag Harvester — For Direct Processing Supply
The EP-CWB-2L Big Bag Harvester is a specialized configuration for Korean potato operations supplying directly to processing plants — chip manufacturers, starch processors, and industrial food companies that receive potatoes in 500 Kg FIBC (Flexible Intermediate Bulk Container) “big bags” rather than in bulk or smaller-unit packaging.
The EP-CWB-2L harvests and grades the potato in-field — eliminating the packhouse intermediate step — and fills the product directly into big bags positioned on the machine. When a bag is full, the operator exchanges it for an empty one without stopping the harvest pass. This in-field packaging approach eliminates the packhouse handling step between field and processing plant delivery: harvested potatoes are loaded from the FIBC bags on the farm directly onto the truck for processing plant delivery, with no bulk grading, sorting, or re-bagging at an intermediate facility.
The EP-CWB-2L is the right choice for Korean potato operations with the following profile: contracted supply to a processing plant that specifies big-bag delivery; operations above approximately 20 hectares where the elimination of packhouse costs is materially significant; and operations where the processing plant is willing to accept sorted and graded product packed directly from the field. For fresh-market potato operations supplying supermarkets, cooperatives, or wet markets — where packaging, grading to fresh-market specification, and retail presentation matter — the EP-AWB series leading to packhouse grading is the more appropriate supply chain.
Harvest Quality — Why Everything Upstream Affects Digger Performance
The EP-AWB digger cannot produce high-quality harvest output from a poorly prepared field. Every preparatory step from stone clearance through to planting directly influences what the digger encounters and how cleanly it performs. Korean operators who invest in the complete Watanabe upstream system report consistently better harvest quality outcomes than operators who use the digger on fields prepared with incomplete or mismatched upstream equipment. The connections are direct:
Stone clearance (Steps 1–3) → Digger share and web longevity. Residual stones above 10–15 cm in the harvest zone contact the lifting shares directly, causing accelerated wear and in the worst case, sudden impact damage that stops the harvest operation. The complete stone clearance sequence — THOR crusher + CT-2100 picker — protects the digger by eliminating the stones that cause share damage. Operators who skip thorough stone clearance to save preparation costs frequently incur higher annual digger maintenance costs that exceed the preparation savings.
Rotavator quality (Step 2) → Soil separation efficiency. The vibrating web separator on the EP-AWB-1600 is most efficient when the harvested soil is loose, friable, and uniform in particle size. Coarse-tilled soil with large unbroken clods — typical of 540 RPM rotavator passes on wet soil — clogs the web and reduces throughput, requiring slower working speed and producing more soil in the harvested tuber stream. Fine-tilled 1000 RPM seedbeds produce the loose, friable soil structure that allows the web separator to work at maximum efficiency.
Row alignment (Steps 3–7 consistency) → Share depth accuracy. The EP-AWB-1600 lifting shares must travel at precisely consistent depth beneath the tuber zone throughout each harvested row. If the row geometry is inconsistent — ridges that vary in height, rows that deviate from the machine’s centreline — the shares must be set conservatively deep to ensure they pass beneath the deepest tubers in the row. This conservative setting produces a larger soil volume per row meter on the web conveyor, reducing separation efficiency and throughput. Consistent ridging (Step 3) and consistent planting depth (Step 5) — both dependent on the quality of Step 2 rotavator tillage — are the upstream prerequisites for optimum share depth setting and maximum digger throughput.
Planning Your Potato Harvest System — Configuration by Farm Type
Small Highland Family Farm — Pyeongchang-gun, 2–5 ha
Configuration: EP-AWB-1600 with Kit A or Kit B. At 2–5 ha annual harvest, the 2-row mounted digger completes the harvest comfortably within a 2–3 day weather window. Kit A (side windrow) for family operations with available manual picking labour; Kit B (rear elevator to cart) for operations transitioning away from manual picking. The 75 HP tractor that runs the furrower, planter, and cultivator is the same tractor for the digger — no additional tractor investment required.
Medium Commercial Operation — Hoengseong-gun, 10–20 ha
Configuration: EP-AWB-1600 Kit B as primary; consider EP-AWB Trailed for flat sections. At 10–20 ha, the weather-window risk begins to be relevant — harvest speed becomes an operational consideration alongside equipment cost. An EP-AWB-1600 Kit B (rear elevator to cart) combined with two collection carts allows continuous harvest operation without stops — one cart collects from the digger while the other is transported to the field headland for unloading. This dual-cart approach increases the effective harvest rate of the 2-row mounted digger to near its theoretical maximum. For flat field sections above 100 m row length, a trailed configuration might be considered as a second machine to further increase throughput on the easiest field sections.
Large Commercial Operation with Processing Supply — 25+ ha
Configuration: EP-AWB-3200 (4-row trailed) for flat sections + EP-AWB-1600 for slope sections; EP-CWB-2L if processing-plant big-bag supply. At 25+ ha, throughput is the primary constraint. Operating both a 4-row trailed (for flat, long-row sections) and a 2-row mounted (for sloped and short-row sections) maximises daily harvested area across mixed field terrain. The EP-CWB-2L is selected instead of the trailed series when the operation has a contracted processing plant that receives and pays premium for big-bag direct-from-field delivery — the elimination of packhouse intermediate handling cost and the supply chain simplification justify the machine investment at this scale.
Frequently Asked Questions — Potato Digger Selection
How exactly do I measure my planted row spacing to confirm digger share compatibility?
After planting, measure the centre-to-centre distance between two adjacent planted rows in multiple locations along the row length — not just at the row ends. Use a tape measure to the ridge centreline (the highest point of each ridge) rather than the ridge edge. Take five measurements at random positions along a 50-metre row length and average them. This average is the planted row spacing that the digger shares must match. Variations of more than 3–4 cm between measurement points indicate inconsistent furrowing or planting — which will produce share mismatch in some sections even if the average matches. Report both the average and the maximum variation to your Korea Watanabe contact when specifying the EP-AWB-1600 share spacing.
What happens to harvested yield if the digger shares are set too deep?
Setting shares too deep (below the tuber zone) moves more soil volume per row metre onto the web separator than the crop volume requires — reducing throughput efficiency and increasing machine wear without benefiting harvest completeness. It does not significantly affect tuber damage. Setting shares too shallow (above the deepest tubers) is the damaging error: shares cutting through the tuber zone bruise and cut tubers below the share tip, creating damage that may not be visible at harvest but accelerates rot in storage. Set shares to travel 3–5 cm below the deepest expected tuber position — this usually means approximately 20–22 cm below the ridge surface for varieties with 15–18 cm maximum tuber depth in Korean highland conditions.
Can the EP-AWB-1600 kit configuration be changed after purchase?
Yes — the Kit A, B, and C configurations are output attachment systems that connect to the same EP-AWB-1600 base machine. Operations that need to change their harvest logistics approach — for example, transitioning from Kit A windrow picking to Kit B mechanical collection as the farm grows — can upgrade the kit without replacing the base machine. Confirm kit interchangeability with Korea Watanabe at the time of initial purchase, and retain the base machine documentation for reference when upgrading. Kit availability and compatibility should be confirmed before committing to an upgrade that was not planned at original purchase.
Is the Korean potato harvest season compressed enough to require two diggers on medium farms?
For operations in the 12–20 ha range with fields at 600+ m altitude where the harvest weather window is consistently 2–3 weeks, a single EP-AWB-1600 Kit B with dual collection carts is typically sufficient — at 0.8–1.2 ha/hour productive harvest rate (accounting for cart exchanges and field turns), 15 ha requires approximately 12–18 productive hours, achievable in 3–4 good-weather working days. Two diggers become a consideration when the harvested area exceeds approximately 25 ha, field conditions are particularly challenging (high stone content requiring slow working speed, steep terrain with frequent headland turns), or when the crop consists of multiple varieties with different maturity windows that must be harvested in strict sequence to maintain variety purity for market specification. Contact us with your specific harvest area, field geometry, and variety schedule for a throughput analysis.
Are government subsidies available for potato harvesting equipment in Korea?
Agricultural machinery subsidies (농업기계화 촉진 지원사업) administered by the Ministry of Agriculture, Food and Rural Affairs (농림축산식품부) include harvest machinery categories in most annual program years. Potato harvesters — including mounted diggers and trailed configurations — have been eligible equipment categories in recent program years. Subsidy rates and eligible equipment categories change annually. Confirm current eligibility with your regional agricultural technology center (농업기술센터) or county agricultural office before purchase, and request technical specification documentation from Korea Watanabe to support the subsidy application process. We can provide the complete technical specification documentation required for subsidy applications for all EP-AWB series configurations.
Tell Us Your Farm — We Confirm the Right Digger Configuration
Annual harvest area + planted row spacing + field slope + supply chain (fresh market / processing / big bag) + tractor HP → specific EP-AWB configuration recommendation with kit selection and row-matching confirmation. All configurations in Korea local stock, Ansan-si, Gyeonggi-do.
Editor: Cxm
