Zhongning Selenium-Sand Watermelon

Zhongning Selenium-Sand Watermelon

Zhongning Selenium-Sand Watermelon is a product with geographical indication for agricultural products.

　　Due to the local gravel being rich in minerals, including essential trace elements such as selenium, zinc, and calcium for the human body, these elements are gradually released through wind and sun exposure, washed into the soil by rainwater, and absorbed by plant roots. This enables the production of sweet, refreshing, and uniquely natural health food. Since the produced watermelons and melons are rich in selenium, they are named "Selenium-Sand Watermelon."

　　According to tests by relevant departments of the Ministry of Agriculture, Selenium-Sand Watermelon contains not only trace elements such as zinc, calcium, potassium, and selenium, but also vitamins, carotene, and 18 kinds of amino acids, all highly beneficial to human health. In particular, selenium can delay aging, enhance immunity, and prolong life. Selenium-Sand Watermelon is highly resistant to storage—left at home or in the office under natural conditions, it will not rot for five months. It is also highly resistant to transport, enduring long-distance shipping of thousands of kilometers without damage, making it one of the best green foods currently available on the domestic market.

　　The Zhongning Selenium-Sand Watermelon base is located in the arid belt of central Ningxia, with excellent light conditions—annual sunshine duration reaches 2,845 hours, and light and heat resources are abundant. The frost-free period lasts 153 days, with large day-night temperature differences averaging 10–16°C. The accumulated temperature ≥5°C is 3,300–3,800°C, and ≥10°C is 3,100–3,500°C, which is even more conducive to the cultivation of Selenium-Sand Watermelon. Planting occurs annually from April to May, with maturity and market availability from July to September. Possessing unique health benefits, it is truly a pollution-free green food. In 2005, Zhongning County’s Selenium-Sand Watermelon passed the review and monitoring of the National Green Food Development Center, with both origin conditions and product quality fully meeting green food requirements. An application was also made to certify 142,000 mu (approximately 9,466 hectares) as a national green food (Selenium-Sand Watermelon) raw material base.

　　Geographic Scope

　　Zhongning County is located in central Ningxia, in the eastern section of the Wei-Ning Irrigation District. It lies between 105°26′–106°07′ east longitude and 37°09′–37°50′ north latitude, at an elevation of 1,184 meters. It borders Litong District and Qingtongxia to the east, Zhongwei urban area to the west, Tongxin County to the south, and Alxa Left Banner of Inner Mongolia to the north. The county spans approximately 50 kilometers from east to west and about 60 kilometers from north to south, covering a total area of 4,198 square kilometers. The main planting areas of Zhongning Selenium-Sand Watermelon are distributed across Baima Township, Mingsha Town, Enhe Town, Zhouta Township, and Hanjiaoshui Township, with a planting area of 23,000 hectares and a total output of 520,000 tons.

　　Natural Ecological Environment and Humanistic Historical Factors

　　(1) Soil and Topography: The northern part of Zhongning County consists of the Weining North Mountains and hills, the central part is the Yellow River alluvial plain, the eastern and southeastern parts feature mountains (such as Niushou Mountain and Yantong Mountain) and hills, while the southwestern part includes the Qingshui River valley plain and Miboshan Mountainous terrain. The soil is nutrient-rich and balanced, with pH value 8.28, mercury 0.03 mg/kg, lead 13.4 mg/kg, cadmium 0.16 mg/kg, arsenic 11.9 mg/kg, chromium 60.5 mg/kg, and copper 19.5 mg/kg.

　　(2) Hydrological Conditions: The Yellow River flows through 68 kilometers of the county, with an average annual flow of 32.5 billion cubic meters. The Qingshui River has a flow of 124 million cubic meters. Within the county, four main irrigation channels—the Qixing Canal, Yuejin Canal, Guhai Canal, and Beitan Canal—serve as the primary sources of irrigation. The total lake area is 445 hectares. The Selenium-Sand Watermelon planting base is part of a dryland farming area relying on natural precipitation, mainly consisting of mountain slopes and hilly land, far from urban and industrial zones, with no pollution sources such as polluting enterprises within the production area.

　　(3) Climate Conditions: Zhongning County has a continental climate, characterized by long winters, short summers, large temperature variations, dryness, little rainfall, intense evaporation, abundant sunlight, and rich heat. The annual average temperature is 9.1°C. During the growing season, the area receives 1,080 hours of sunlight, with a sunshine percentage of 65%, a frost-free period of 165 days, effective accumulated temperature of 2,529.3°C, and day-night temperature differences during May to August generally ranging from 15.5°C to 12.6°C. Annual precipitation is 221.6 mm, mostly concentrated in July, August, and September. Annual evaporation is 2,055.3 mm, 9.3 times the amount of precipitation. The average annual relative humidity is 52%. The total annual solar radiation is 5,924 MJ/m². Spring is windy, with an average wind speed of 2.9 m/s and maximum wind force reaching level 12. “Wearing a fur coat in the morning and a gauze scarf at noon, then sitting around a stove eating watermelon at night” is a true depiction of the region’s climatic characteristics.

　　(4) Humanistic and Historical Background: The gravel-covered fields embody the crystallization of the hard work and wisdom of generations of laborers in our county. Zhongning County has been cultivating Selenium-Sand Watermelon since the 1940s, boasting over 70 years of planting history. In the past, due to lack of funds, poor transportation, absence of policy support, and livelihood pressures, locals spontaneously planted the watermelons sporadically, treating it merely as a side occupation. To grow Selenium-Sand Watermelon, gravel must first be laid on barren land. In the past, due to inconvenient transportation, the investment time for planting gravel watermelon was long, and returns took even longer. Moreover, after many years of planting, crop rotation was required. As a result, locals in the 1970s had a saying about gravel watermelon: “Hard on the father, rich for the son, worrisome for the grandson.” However, with continuous improvement in planting techniques, gradual expansion of planting areas, better resolution of water supply issues, and enhanced mechanization, labor intensity significantly decreased. Gravel watermelon entered a phase of rapid development in the 1990s. Selenium-Sand Watermelon is referred to by locals as “watermelon grown from stones,” a distinctive melon-growing model that fully utilizes the advantages of mountainous land resources. It can even be considered a unique creation in the world. It has not only achieved considerable economic benefits but also brought notable ecological and social benefits—reducing land desertification, improving land utilization, and boosting the rapid development of secondary and tertiary industries. By 2008, the cumulative planting area of Selenium-Sand Watermelon in townships such as Hanzhao Shui, Mingsha, and Baima in our county reached 23,000 hectares, involving 6,000 farming households, making it an industry that helps farmers in the central arid belt of Ningxia “pull out the roots of poverty.”

　　Production Technical Requirements

　　(1) Origin Selection: Select flat or gently sloped, deep-soiled, moderately fertile, sunny fallow mountain land or wheat and bean stubble fields as plots for gravel pressing.

　　(2) Variety Selection: Choose disease-resistant, drought-resistant, high-quality, high-yield, storage- and transport-tolerant, and marketable varieties. Seed quality should meet the requirements for melon and vegetable crop seeds. Varieties such as Black Beauty, Xin Jinlan, Jincheng No. 5, XNong 8, and Gaoke Guanlong can be selected.

　　(3) Production Process Management: In the production process of Selenium-Sand Watermelon, key steps include gravel laying on mountain land, seed treatment, and pest and disease control.

　　① Gravel Bed Installation

　　Select flat or gently sloped, deep-soiled, moderately fertile, sunny fallow mountain land or wheat and bean stubble fields as plots for gravel pressing. In arid regions, a mixture of sand and stone (with a ratio of 3:7 or 4:6, and a gravel layer thickness of 15–20 cm) is used to conserve water, maintain soil moisture, suppress alkalinity, and increase ground temperature—an improved type of arable land suitable for crop cultivation. The thickness of the gravel layer depends on the coarseness of the sand and stone; coarser gravel requires a thicker layer, finer gravel a thinner one. A 4:6 ratio of sand to stone is optimal. Typically, 100–120 cubic meters of gravel are applied per mu. The soil should be plowed and sun-dried before gravel laying to enhance nutrients.

　　② Seed Treatment Measures

　　Seeds should be purchased from high-quality varieties. Use methods such as warm scald soaking, potassium permanganate disinfection, and disinfection with carbendazim or formalin for unified seed disinfection before sowing.

　　③ Strengthen Pest and Disease Control

　　Implement comprehensive agricultural measures and practice reasonable crop rotation to reduce disease occurrence. Common rotation methods include: ① Staggered sparse planting rotation; ② Watermelon–melon–fallow method; ③ Melon–wheat rotation.

　　Enhance pest and disease forecasting, monitor pest density in a timely manner, and issue early warning bulletins. In areas with conditions, carry out unified prevention and control. Follow pesticide safety cooperation standards and guidelines for rational pesticide use, actively promote biological control, and apply chemical control appropriately.

　　Principles to follow for chemical control:

　　a. Strictly comply with national regulations; prohibit the use of highly toxic, high-residue, high-bioaccumulation, and teratogenic (toxic, carcinogenic, mutagenic) pesticides and their mixtures. Do not use unregistered pesticides.

　　b. When using chemical agents, strictly adhere to national standards for rational pesticide use, including specified dosages and frequencies. Only use pesticides that have passed pesticide residue testing.

　　c. Strictly enforce maximum residue limits, usage frequency limits, and safety intervals for pesticides.

　　Strictly enforce the maximum residue limits, usage limits, and safety intervals for pesticide application.

　　Methods for the scientific use of pesticides: accurately identify the types of pests and diseases, use pesticides in a targeted manner, understand the occurrence patterns of pests and diseases, and apply control measures at the optimal prevention period; strictly adhere to the proper dosage and application methods of pesticides, scientifically and rationally mix different pesticides, and alternate pesticides with different modes of action to delay or avoid

　　the development of pesticide resistance in pests and diseases; whenever possible, apply pesticides directly to the target areas, remove centrally infected plants, and spray surrounding plants for control; use spraying equipment with good atomization to ensure thorough and even application, select optimal spraying times to improve efficacy.

　　④ Promote scientific fertilization techniques

　　In selenium-sand melon production, where conditions allow, increase the application of organic fertilizers and develop organic compound fertilizers, prevent overuse or excessive application of nitrogen fertilizer, and strictly observe the safety interval for nitrogen fertilizer application. The use of untreated organic fertilizers and other toxic fertilizers is prohibited.

　　Fertilizer use and management: the use of commercial fertilizers must be approved by technical personnel, or purchased from designated fertilizer supply points. The use of organic fertilizers must comply with the requirements outlined in the technical guidelines.

　　Fertilization principles: as the nutrient content of selenium-sand melon fields gradually decreases with the number of years of cultivation, and the sandy soil becomes compacted over time, it is essential to rigorously perform sand loosening and fertilization.

　　Requirements for the safe application of nitrogen fertilizer: adjust the amount of fertilizer applied according to specific conditions, ensuring economically reasonable nitrogen use; strictly follow the safety interval for nitrogen fertilizer application, and for vegetables where stems and leaves are the edible parts, prohibit top-dressing nitrogen fertilizer within 20 days before harvest; promote a "control nitrogen, stabilize phosphorus, increase potassium" fertilization model.

　　(4) Product harvesting: for sales outside the region, harvest when the melons are 7–8% ripe; for local sales, harvest only when fully ripe. Avoid selling unripe melons. Do not apply any disease or pest control pesticides within 15 days before harvesting.

　　(5) Production record requirements: farmers are required to keep detailed records during the planting process, including the names, formulations, specifications, application methods, timing, dosage per application, total annual applications, and date of last use of all pesticides and fertilizers used.

　　Typical quality characteristics of the product and product quality and safety regulations

　　(1) External sensory characteristics: Zhongning selenium-sand melons are large with thick rinds, elliptical in shape, and have dark green striped skin.

　　(2) Internal quality indicators: the unique planting methods and natural conditions produce melons that are large, with red flesh, juicy, tender, sweet as honey, and with sugar content as high as 13.8%. The produced melons have comprehensive and balanced nutritional elements. These include 18 essential amino acids for humans, 3 types of vitamins, and 5 types of trace elements, among which calcium is 56mg/kg, potassium 1090mg/kg, and they particularly contain essential trace elements for human health such as selenium and zinc, which offer anti-aging, longevity-promoting, and anti-cancer benefits, giving them unique health value—hence the name “selenium-sand melon.” They are truly pollution-free green food.

　　(3) Safety requirements: Zhongning selenium-sand melons strictly comply with the (NY5109-2005) standard.

　　Packaging, labeling, and related regulations

　　(1) Packaging: containers used for packaging must be clean, dry, sturdy, breathable, free of contamination or odors, with no sharp protrusions inside, and cardboard should not be damp or delaminated.

　　(2) Labeling: label users must uniformly use agricultural product geographical indication labels (a combined format of the Zhongning selenium-sand melon name and public identification mark) on their products or packaging.

　　(3) Transportation: loading, unloading, and transportation should be carried out quickly, with care taken to handle products gently. Protection against rain and heavy showers during transit is necessary. When transporting bulk melons, padding should be added to the bottom and sides of transport vehicles where the fruit comes into contact, to prevent mechanical damage. Vehicles, tools, padding materials, and rain protection facilities used for transport must be clean, hygienic, dry, uncontaminated, and must not be mixed with other toxic or harmful goods.

　　(4) Storage: storage should take place in ventilated, cool, clean, and hygienic locations. Stacking should be neat to prevent crushing or damage, and protection from sunlight, rain, freezing, and contamination by toxic or harmful substances is essential. For long-term storage, low-temperature cold storage is recommended. During storage, melons should be sorted by variety and specification, and pre-cooled gradually before being placed in storage. The storage room should maintain suitable temperature and relative humidity. During the storage process, regular inspections should be conducted, and any diseased melons should be removed immediately. Storage must not involve mixing with other toxic, odorous, harmful, moldy, heat-generating, or pest- and disease-transmitting items.