Lixian Ma Shan Yao 蠡县麻山药 (Lixian yam)
PGI 受保護的地理標誌 Lixian Ma Shan Yao 蠡县麻山药 are yams from the region of Li County (Lixian), Hebei Province of China and are the tubers of Dioscorea batatas Decne, which belongs to the family Dioscoreaceae. They are planted by traditional cultivation techniques in a loose sandy loam fluvo-aquic soil (chao soil) formed by long-term erosion and deposition. Besides fresh goods, Lixian Ma Shan Yao also refers to the dried product, including dried yam strips and chips. The fresh yams are selected as raw materials, then peeled and sliced manually or mechanically. The slices are then either air-dried or dehydrated in a drier. For the fresh Lixian Ma Shan Yao, there are three cultivars: Bangyao, Ziyao and Xiaobaizui. The characteristics of each are as follows:
1. Bangyao: Tuber cylindric, 35-60 cm in length, not less than 3,5 cm in diameter; long dense fibrous roots; thin tawny integument; crisp white flesh, thick mucus; daintily sweet and mild but flavourful, tingling taste after cooking; water content 75-85 % (three months after harvest).
2. Ziyao: Tuber cylindric, 50-80 cm in length, not less than 1,5 cm in diameter; sparse fibrous roots; dark-brown integument, purple speckles on the light-coloured integument; fibrous flesh texture, white transverse section, abundant starch content; deliciously sweet taste after cooking; water content 75-85 % (three months after harvest).
3. Xiaobaizui: Tuber cylindric, 40-70 cm in length, not less than 1,6 cm in diameter; thin fibrous roots; thin hazel integument; soft floury flesh; deliciously sweet taste after cooking; water content 75-85 % (three months after harvest).
Dried Lixian Ma Shan Yao includes both yam strips and chips.
1. Yam strips: made of fresh, peeled and dehydrated yams; approximately cylindrical shape, smooth, uniform in size; yellow-white, crisp taste, water content 6-8 %.
Concise definition of the geographical area: The geographical area covers a total area of 345 square kilometres, townships and towns along the Zhulong River, namely Qudi Township, Liushi Town, Baoxu Town, Nanzhuang Town, Liwu Town, Guodan Town and Baichi Town.
Specificity of the geographical area: Lixian Ma Shan Yao has been cultivated for more than 2 000 years, in the geographical region of Li County. It is located in the Bohai Bay Basin and the depressed western plain in central Hebei, North China. The landform is a plain consisting of alluvial and diluvial deposits from the Quaternary period. The land gently tilts, with no significant fluctuations, and is higher in the southwest and lower in the northeast. The average altitude is 15,6 m, with a very slight slope (0,03-0,01 %). Li County is located in an eastern monsoon warm temperate semi-arid area, which has a marked continental monsoon climate. There are distinct seasons — spring is windy and dry, summer rainy and hot, autumn clear and crisp, while winter is cold and dry. It has abundant light, heat and water resources. The prevailing wind direction is south-southwest through the whole year.
Other geographical features are as follows: annual average frost-free period: 176 days, annual average ground temperature: 13 °C, annual average air temperature: 12,2 °C (monthly maximum temperature: 26 °C), average annual sunshine: 2 628,7 h, average annual total solar radiation: 106,9 kcal/square cm, annual maximum depth of snow cover: 23 cm, average annual precipitation: 487,2 mm.
Specificity of the product: Lixian Ma Shan Yao products have unique characteristics among the yam cultivars, and are especially well known for their mild but flavourful tingling taste. Water content in fresh yams (three months after harvest) is 75-85 %. Dried Lixian Ma Shan Yaos are of close texture, water content 6-8 %, protein not less than 4,5 %, total sugar not more than 15 %.
Soil condition: Zhulong River runs through Li County, conferring a particular geology and soil. Li County is located in a deposition zone in North China with many soil deposits from the Quaternary period. Most soil is sandy fluvo-aquic, from repeated Zhulong River floods. About 37 % of cultivated land in the county is sandy soil. Most of the soil in yam-producing areas is sandy alluvial fluvo-aquic. The soil layer is deep and loose with good permeability, favouring cultivation. Most of the soil is moderately fertile. Soil nutrients in the plough layer include: organic matter 0,78 %, total-N 0,065 %, total-P 0,076 %, Olsen-P 0,9 mg/kg, available K 91 mg/kg and soil pH 7,4-8,9, which ensures that Lixian Ma Shan Yao has many beneficial features, such as a symmetrical shape, short tapered ends, long tubers, thin integument, sparse fibrous roots, smoothness and no tumours on the tuber. Protein content in Lixian Ma Shan Yao is typically higher than in other yams.
Climatic conditions: Li County is located in the eastern monsoon warm temperate semi-arid area. The frost-free period is 177 days per year, average annual rainfall 471 mm, mainly concentrated from June to August, and average annual evaporation 1 837,4 mm. Adequate light and heat resources are extremely beneficial to the growth of yam. In addition, good quality water and convenient irrigation help to ensure many specific features of Lixian Ma Shan Yao, such as very good medicinal properties and flavour, high protein content, low sugar, high mucus and low moisture.
Human Factors: Local producers use traditional methods, such as A-brackets, tripods and tetrapod supports, ensuring that each yam can obtain adequate light and heat as it grows. Because of the soil conditions, flexible watering schedules and rapid soil drainage, the soil remains generally moist and disease-free during the growth period.
Historical Origin: Compared with other cultivars of yams, Lixian Ma Shan Yao has a mild but flavourful tingling taste that has gained it a strong reputation as a high-quality traditional product. It makes Lixian Ma Shan Yao well known and called the famous ‘Ma Shan Yao’. Cultivation of Lixian Ma Shan Yao has a long local history, and the yam has been widely planted since ancient times. Many legends, stories and poems about yams have been told by many people. For example, ‘Merchant Fanli stayed at Liushi town and the beautiful woman Xishi tasted the yam’, ‘A sickly and weak daughter of Mr Bai in Hu village, changed into a beautiful and healthy palace maid after eating the yam’, ‘Emperor Qianlong passed by Li County on his way to the South and his liegeman, Mr Ji Xiaolan, wrote a well-known poem on the yam’.