Key Points of High-Yield Winter Cultivation Techniques for Potatoes

I. Site selection and land preparation. For winter-planted potatoes, choose sandy loam soil with convenient transportation, deep topsoil, good drainage and aeration, rich organic matter, sufficient water sources, convenient irrigation and drainage, slightly acidic, and with rice as the previous crop. Land preparation should involve deep plowing and fine harrowing, ensuring the loose soil layer reaches more than 8 cun; form ridges and beds, with double-row planting ridge surface width of 2.5-2.8 chi, furrow width of 7-8 cun, requiring fine and crumbly soil clods, with ridge surfaces and furrow bottoms level and straight.

II. Seed potato treatment and cutting. After purchasing seed potatoes, remove diseased, rotten, and mixed potatoes, spread out the good seed potatoes and spray with 200-fold formalin or 600-fold Daconil solution, cover with plastic film and fumigate for 2 hours, then ventilate and air-dry, then transfer to a cool, dry, ventilated place with light exposure for storage; before cutting, each person prepares two cutting knives and a basin of 75% alcohol or 0.5% potassium permanganate solution, and immerses the cutting knives for disinfection. When cutting, after each knife cuts one seed potato, immerse it in the disinfectant solution for disinfection, and switch to another knife for the next cut. Cutting should be done 1-2 days before sowing, ensuring each seed piece has 1-2 buds, weighing 20-30 grams, and try to cut the seed pieces into square shapes. Store the cut pieces classified by sprouting status or position on the seed potato in a cool, dry place with scattered light, and sow after the wounds heal.

III. Sowing. In the coastal and riverside areas of Huidong County, sowing can be done from late October to early December, but mid-November is optimal; in mountainous areas, to avoid frost, sow in early October or late December. When sowing, plant seed pieces with similar sprout lengths in the same ridge to facilitate uniform emergence, with the buds facing upward, and cover with 1.5-2 cun of soil on top of the seed pieces. After sowing, cover the ridge surface with rice straw. The sowing specifications and growth periods of each variety are shown in the attached table. IV. Fertilization. Fertilization should combine organic fertilizer with inorganic fertilizer, and basal fertilizer with topdressing, and the proportions should be appropriate. Generally, basal fertilizer should account for about two-thirds of the total fertilization. Based on an expected yield of 3000 jin per mu, the fertilization plan for medium-fertility soil is as follows

Basal fertilizer: 20-30 dan of farmyard manure (containing more than 500 jin of chicken manure or pig manure) + 60 jin of superphosphate, composted for more than 20 days, applied in furrows mixed with 60 jin of high-quality compound fertilizer (N, P, K total content above 35%) + 15 jin of potassium sulfate when forming ridges.

Topdressing: Generally 3-4 times for early-maturing varieties and 4-5 times for late-maturing varieties. The first application is when 50% of seedlings emerge, then every 7-10 days thereafter, with the amount determined based on the fertilization plan and adjusted according to growth conditions. Generally, for the 1st-2nd applications, use 20-25 jin of compound fertilizer (15-15-15) + 5-8 jin of urea per mu; for the 3rd-5th applications, use 20-25 jin of compound fertilizer + 6-8 jin of potassium sulfate dissolved in 3000 jin of water for drenching per mu. From early to late stage, nitrogen fertilizer decreases and potassium fertilizer increases.

Foliar fertilizer: During the seedling stage, bud stage, and tuber bulking stage, use Shengtuosu, Yunda-120, tuber bulking agent, potassium dihydrogen phosphate, etc. respectively. For Jinguan and Helan varieties, within 30 days before harvest, 1 gram of 920 can be diluted in 150 jin of water for spraying.

V. Water management. The entire growth period requires maintaining uniform soil moisture. For soil that is too dry before sowing, first conduct furrow irrigation with running water, and sow after soil moisture drops back to 80%. If the soil is too dry after sowing, use furrow irrigation to moisten the soil, filling water to one-third of the furrow depth, retaining for several hours, and immediately draining when the soil at 3 cun depth in the middle of the ridge is moistened. Never over-irrigate.

VI. Seedling thinning and hilling. At the uniform emergence stage, for export-type varieties, select the 1-2 strongest plants per hill and keep them; for processing-type varieties, select the 3 strongest plants per hill and keep them, cutting off excess seedlings. When seedlings are 4-6 cun tall, hill up promptly, ensuring no gaps on the ridge surface, with hilling thickness reaching more than 2.5 cun, and minimizing damage to stems and leaves during hilling.

VII. Pest and disease control. Apply 5-6 jin of Miral per mu mixed with basal fertilizer in furrows to control underground pests. At the uniform emergence stage, spray with 3000-fold Kungfu + 1500-fold Kulong to control mites, aphids, etc. If underground pests and bacterial wilt dead seedlings are found, drench roots with 1.5 jin of trichlorfon crystals and 500 ml of Kejun respectively. At the last fertilization, apply 1.5 jin of methyl parathion per mu to control potato tuber moth. Begin controlling late blight from the insect stage, and spray 600-fold Daconil (25 grams diluted in 15 kg of water) for prevention before disease onset. Once diseased plants are found, spray 600-fold Ridomil or Jinglei Ridomil per mu, spraying 2-3 times consecutively.