Xining City, located in the eastern part of Qinghai Province, is situated on the upper reaches of the Youshui River, a tributary of the Yellow River. The city experiences a plateau climate with cold winters, cool summers, and mild springs and autumns. It has a large daily temperature difference, with an average annual temperature ranging from 3 to 6°C. Xining enjoys abundant sunshine, averaging about 2,793 hours per year, and has a frost-free period of around 180 days. Annual rainfall ranges between 450 to 820 mm, making it ideal for growing carrots.
Carrots have been cultivated in Xining for many years, with significant growth since 2005. At that time, the sown area reached 2,500 hectares, with an output of 5,500 kg per mu (approximately 667 square meters) and an output value of 2,000 yuan. The local variety of carrots is known for its high sugar content—6.96%—and is rich in carotene and other essential trace elements. As a result, Xining carrots are considered the best in their category domestically and are highly favored by consumers both inside and outside the country. They are exported to South Korea, Japan, and major cities such as Xi'an, Zhengzhou, and Guangzhou.
The following outlines effective high-yield cultivation techniques for producing clean, pollution-free carrots in the Xining region:
1. **Soil Selection**: Choose sandy loam or loam that meets the standards for pollution-free vegetable production. The soil should be deep, loose, and well-drained to support healthy root development.
2. **Variety Selection**: Opt for varieties with good cold tolerance, high yield, disease resistance, and commercial quality. Suitable options include New Kuroda Five-inch, Product Wax, Dahongding, and Quansheng.
3. **Soil Preparation and Fertilization**
- **Soil Preparation**: Deep plowing (20–30 cm) is essential. Two rounds of plowing help loosen the soil and ensure good seedling emergence. High ridges are recommended, with ridge spacing of 40–50 cm and height of 15–20 cm.
- **Fertilization**: Apply 3,000–5,000 kg of decomposed organic manure, 25 kg of compound fertilizer, and 2 kg of phoxim per mu (about 667 square meters) to improve soil fertility and prevent pests.
4. **Seed Treatment**: Soak seeds in warm water (50°C) for 25 minutes, then in water at 15–25°C for 4–5 hours. Germinate them for 5–7 days at 20–25°C, and store at 0°C for 3–5 days before planting.
5. **Sowing**: Sow between late April and early May, using 0.5–0.75 kg of seeds per mu. Mix with fast-growing crops like Chinese cabbage, radish, and spinach to provide shade and improve germination.
6. **Field Management**
- **Weeding**: Regular weeding is crucial, especially during the early growth stage when weeds grow rapidly. Manual weeding or herbicides can be used.
- **Watering**: Maintain soil moisture at 60–70% during germination. Water more frequently during root expansion, but avoid overwatering to prevent cracking.
- **Stem Covering**: Keep the carrot shoulders exposed by covering them with soil, but do not bury the stem center.
- **Fertilization**: Apply two to three topdressings of diammonium phosphate, potassium sulfate, or urea during the growing season to promote root development.
7. **Pest and Disease Control**
- **Black Spot and Black Rot**: Use resistant varieties, rotate crops, and apply fungicides like chlorothalonil or mancozeb.
- **Bacterial Soft Rot**: Improve drainage, remove infected plants, and spray neemectin or streptomycin.
- **Mosaic Virus**: Prevent aphids and apply viral control agents like virus rick or phytopathogenic spirit.
- **Insects**: Use phoxim or cypermethrin to control underground pests and aphids.
8. **Harvesting and Storage**: Harvest when about 80% of the outer leaves turn yellow and wilt, typically between early September and late October. Store in woven bags at 1°C with 90–95% humidity for up to 5–6 months.
Author: Xining Agricultural Technology Promotion Station, Qinghai Province.
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