Detailed Explanation of the Technical Regulations for Pollution-Free Production and Cultivation of Specialty Black Sweet Potato

Specialty black sweet potato has unique quality, high nutritional value, and is rich in various amino acids and trace elements such as potassium, manganese, zinc, iodine, and selenium, as well as carotene, anthocyanins, sugars, proteins, and fats. It has obvious anti-cancer, cancer-preventing, and health-care functions. Market demand is growing day by day, and the prospects are promising.
I. Main Content
This standard specifies the technical requirements and operating methods for each link in the production process of specialty black sweet potato, including seed potato selection, seedling raising, land preparation, fertilization, planting, field management, pest and disease control, and harvesting and storage.
II. Referenced Standards
GB3095-1996 Air Quality Standard
GB5084-1992 Water Quality Standard for Farmland Irrigation
GB9173-1988 Maximum Allowable Concentration of Air Pollutants for Crop Protection
GB15618-1995 Soil Environmental Quality Standard
GB4285-1989 Standard for Safe Use of Pesticides
GB8832.1.3-1987 Standard for Rational Use of Pesticides
III. Production Base
In sweet potato production areas and high-yield areas, establish a production base in locations with convenient transportation, far from main traffic roads, free from environmental pollution, with water source and soil quality meeting the requirements of the "Technical Specifications for Pollution-Free Agricultural Product Production," flat terrain, convenient drainage and irrigation, guaranteed harvest despite drought or excessive rain, fertile soil, relatively thick plow layer, and where the local people have relatively high scientific planting technology.
IV. Variety Selection
Select black sweet potato varieties with excellent quality, high yield, strong stress resistance, and high marketable rate, such as American Short-Vine Black Sweet Potato, Japanese Purple Sweet Potato King, Jishu 18, Ningshu No. 5, Xuzi No. 1, etc.
V. Seedling Raising
1. Select first- and second-generation seed potatoes of original stock bred at the good-seed propagation bases of scientific research institutions, and eliminate third-generation seed potatoes.
2. Seedling raising time: late February to early March.
3. Seedling raising method: Adopt the method of raising seedlings in heated hotbeds or fermented heating hotbeds inside plastic greenhouses. Uniformly raise and propagate seedlings, and cultivate strong seedlings. The standards are: seedling age 30-35 days, weight of 100 plants 0.75-1 kg, seedling length 20-25 cm, stem thickness 5 mm, leaves thick and fleshy, moderate in size, dark green and free from pests and diseases.
VI. Land Preparation and Ridging
For spring sweet potato, deep plowing and freezing of the soil should be carried out during autumn and winter, with a plowing depth of about 30 cm. In spring, re-plow, level, and break up the soil, then form ridges. Combine this with the application of sufficient organic fertilizer. For summer sweet potato, plow and form ridges promptly after the previous crop is harvested. When forming ridges, the soil should preferably be dry rather than wet, with no clods on top and no buried clods below. Ridge spacing 100 cm, ridge height 30-40 cm, top width 40 cm, achieving uniform ridge spacing, deep furrows and high ridges, full ridge shape, and fine, level ridge surface.
VII. Fertilization
1. Fertilization principles: Control nitrogen, stabilize phosphorus, increase potassium application and supplement zinc and boron fertilizers, promote the use of decomposed organic fertilizer, biological bacterial fertilizer, and high-quality foliar fertilizer. The use of nitrate nitrogen fertilizer, hospital-type fecal waste and municipal waste, and inferior fertilizers containing excessive harmful substances is prohibited. Control the amount of inorganic nitrogen used, advocate the combined application of chemical fertilizer and organic fertilizer, with the ratio of organic nitrogen to inorganic nitrogen preferably 1:1. For potassium fertilizer, choose potassium sulfate. The use of compound fertilizer containing potassium chloride is prohibited.
2. Fertilization method: Promote formula fertilization, and according to soil fertility and target yield, achieve a reasonable combination of nitrogen, phosphorus, and potassium. During land preparation, apply 70% of the organic fertilizer as base fertilizer, and apply the remaining 30% of the organic fertilizer and all chemical fertilizers concentrated at the ridge bottom during ridging, plowing them into the ridge as core fertilizer.
3. Fertilization amount
Under normal circumstances, for fields producing 37,500-45,000 kg of fresh sweet potato per hectare, apply 45,000-60,000 kg of organic fertilizer per hectare, 105-150 kg of pure nitrogen, 75-120 kg of phosphorus pentoxide, and 225-300 kg of potassium oxide. For fields deficient in boron and zinc, supplement 15-22.5 kg each of zinc sulfate and borax per hectare.
VIII. Planting
1. Planting time: Spring sweet potato can be planted when the 10 cm soil temperature steadily passes 15°C, striving for early planting at the appropriate time. Generally planted in mid-to-late April. Summer sweet potato should be planted before June 15.
2. Planting technique: Use the flat planting or slanting planting method, with a planting depth of 5-7 cm. Water thoroughly, seal and compact firmly, plant large and small seedlings separately, and do not plant overnight seedlings or seedlings with pests and diseases.
3. Reasonable close planting: Large ridges with double rows, cross planting, plant spacing 30-40 cm, spring sweet potato 45,000-52,500 plants/hectare, summer sweet potato 52,500-60,000 plants/hectare.
IX. Field Management
1. Filling gaps: 5-7 days after planting, select strong seedlings and inspect the field to fill gaps.
2. Weeding: Before ridge closure, shallow hoe to remove weeds, combined with loosening soil and building up ridges. The use of chemical herbicides is strictly prohibited.
3. Control excessive vine growth; turning vines and applying chemical inhibitors are strictly prohibited. 4. Foliar fertilization: After ridge closure, apply appropriate amounts of foliar fertilizer according to growth vigor and appearance. Options include 0.5% urea solution, 0.2% potassium dihydrogen phosphate solution, or 20% superphosphate solution, as well as high-quality foliar fertilizer mixtures. 5. Drainage: Irrigate promptly to supplement soil moisture during drought, and drain promptly in case of waterlogging.
6. Pest and disease control:
(1) Implement transfer quarantine in accordance with the quarantine operating regulations for sweet potato seeds and seedlings.
(2) Practice crop rotation, and select plots where sweet potato has not been planted within 3 years to plant black sweet potato.
(3) For pests, during land preparation and ridging, apply 2 kg of 2% phoxim granules per mu mixed with 15-20 kg of fine soil and broadcast, then plow into the soil. It can also be applied in holes at the root zone during planting. For diseases, during seedling raising, soak seeds for 10 minutes in an 800-1,000 times aqueous solution of 40% carbendazim suspension concentrate, or soak roots during planting.
(4) During the growing period, promptly select low-toxicity chemical pesticides to control aphids, sweet potato hornworm, tobacco cutworm, sweet potato leaf miner, and other pests. The use of 3911, 1605, 1059, BHC, DDT, carbofuran, aldicarb, chloropicrin, aldrin, monocrotophos, fenitrothion, carbophenothion, pentachlorobenzyl alcohol, omethoate, isofenphos-methyl, methamidophos, trichlorfen, chlordimeform, quintozene, and other pesticides with high toxicity, high residues, and "three-carcinogenic" effects is strictly prohibited. Strictly follow GB4285-1989 "Standard for Safe Use of Pesticides" and GB8832.1.3-1987 "Standard for Rational Use of Pesticides."
X. Timely Harvest and Scientific Storage
1. Harvest time: Generally, spring sweet potato is suitable for harvest in mid-to-late October, and summer sweet potato from late October to early November.
2. After spring sweet potato is harvested, it should be sold or processed promptly, and can be sliced and sun-dried or made into starch.
3. Storage and freshness preservation:
(1) After summer sweet potato is harvested, carefully select and remove diseased, rotten, damaged, injured, or small tubers, and store them in cellars by grade or sell them directly. When putting them into cellars, handle them gently and transport them carefully, and put them into the cellar the same day they are harvested. Do not let tubers remain overnight in the open field. Finish storage before and after the first frost to prevent cold damage and cellar rot.
(2) Regarding storage capacity, according to the local groundwater level and storage habits, build storage cellars suited to local conditions. For concentrated and contiguous production bases, because the storage volume is large, large house cellars can be built for centralized storage to facilitate management and sales. Regardless of the type of cellar used, good insulation performance and ease of management are required.
(3) Management during storage: Regulate temperature well, keeping cellar temperature controlled between 10-15°C and humidity maintained at around 90%. Pay attention to frequent inspections and do not be careless.