Korean Highland GAP Certification: Stone Clearing Guide

Stone clearing is not listed as an explicit named requirement in the Korean GAP standard text. However, the NAAS inspection framework evaluates “physical contamination management” under Domain 1 (Soil and Field Management), and stone presence in production fields is the primary physical contamination risk for Korean highland potato. NAAS inspectors who find stone populations in the production fields during the inspection visit typically identify it as a deficiency under the physical contamination management item — requiring the farm to demonstrate a remediation plan before recertification. In practical terms, Korean highland potato farms with un-cleared granite soil consistently fail or receive corrective actions in the physical contamination management domain, while farms with documented stone clearing history consistently pass this domain. The distinction between “formally required” and “practically necessary for inspection pass” is academic — the evidence across Korea Watanabe’s customer farm network is that stone clearing is necessary for reliable Korean highland GAP certification.

Korean GAP certification involves two types of cost. The application fee is relatively modest — typically 200,000–500,000 KRW per farm operation (not per hectare), payable to the certifying body at application. The more significant cost is the time investment in documentation preparation and system establishment in the year before first inspection — estimated at 3–5 days of administrative work spread across the season for a farm that is already maintaining machine operating logs and grade-out records. Once the documentation system is established, the annual maintenance cost drops to approximately 1–2 days per season. The application process: (1) Submit application to the NAAS county office in January; (2) Receive confirmation and inspection date (typically September–October); (3) Prepare documentation throughout the growing season; (4) Inspection visit — typically 2–4 hours; (5) Certification decision within 20 working days. Renewal is every 2 years with an annual compliance report in the intervening year. Korea Watanabe advises customers on the documentation preparation process and can provide template record-keeping forms as part of the farm system planning service.

Yes, but it requires careful planning of the documentation timeline. If the THOR 2.4 stone clearing begins in April and the NAAS inspection is in October, the farm will have 6 months of stone management operating logs available at inspection — which is generally sufficient to demonstrate the stone management programme is in place. The inspector evaluates whether a system exists and is being maintained, not whether it has been running for a specific number of years. The more challenging element for first-year applicants is the previous season’s grade-out record — the inspection requires crop quality evidence from the current and previous season. A first-year clearing farm’s previous season record will show the pre-clearing Grade 1 proportion (typically 55–68%). Some inspectors accept this as the baseline from which the improvement is being documented; others require evidence of improvement within the inspection window. Korea Watanabe recommends that first-year clearing farms apply for GAP certification in Year 2 (when the first post-clearing season’s grade-out record is available) rather than Year 1, unless the first year’s documentation is exceptionally complete and the Grade 1 improvement is already visible in the partial-season harvest data.

Premium Korean supermarket chains (Lotte Mart’s own-brand, Emart’s premium tier, SSG’s highland specialty channel) apply a 30–60% price premium over cooperative wholesale for GAP-certified Korean highland Dubaek potato. At peak demand periods (January–February, when cold storage premium channel pricing applies), the GAP + certified origin combination can produce net prices of 2,500–4,500 KRW/Kg vs 800–1,400 KRW/Kg at cooperative. Over 10 ha at 27 t/ha, the revenue difference between cooperative channel and premium supermarket channel (at January pricing) represents 40M–80M KRW additional revenue per season — substantially more than the certification and stone management combined cost. The practical barrier for most Korean highland farms is not the certification cost but meeting the supply volume, quality consistency, and logistical requirements that premium supermarket procurement teams specify. Stone clearing is the quality management practice that enables the Grade 1 consistency those procurement specifications require.

The Korea Watanabe stone management and soil preparation system — specifically the THOR 2.4 rock crusher, CT-2100 rock picker, PSW-3200, and DCW 2.2 — when operated with proper record-keeping, generates documentation evidence that addresses Domains 1, 3, and 4 of the NAAS GAP inspection framework. This covers the most commonly failed inspection items for Korean highland farms. The two domains not directly addressed by the Korea Watanabe machines are Domain 2 (pesticide management — this requires separate pesticide application records maintained by the farm) and Domain 5 (post-harvest storage — requiring the EP-AWB harvester cleaning log and cold storage temperature records if applicable). A Korean highland potato farm that operates the complete Korea Watanabe system with proper record-keeping and maintains pesticide application records in the NAAS-approved format has all the evidence needed for a first-inspection pass. Korea Watanabe provides the record-keeping template forms and a GAP documentation preparation consultation as part of the complete system purchase — contact Korea Watanabe for the complete GAP readiness package for your farm.