How to Grow Konjac for High Yield? The Latest Technical Method Tutorial
Konjac, also known as konnyaku, moyu, and ruotou, is a perennial herbaceous plant of the genus Amorphophallus in the Araceae family. China began cultivating konjac as early as over two thousand years ago, and its history as a food is equally long. It is mainly distributed in Yunnan, Guizhou, Sichuan, southern Shaanxi and western Hubei. As konjac continues to be developed and utilized, its cultivation has good prospects for development. Below, let us take a look at high-yield konjac cultivation techniques!
Site Selection and Land Preparation
Konjac has strict requirements for light, heat, water, fertilizer and other conditions, so it is essential to match the site to the soil and plant according to local conditions. Choose slightly acidic to neutral (pH 6.5-7) soil that is deep, fertile, loose and well-drained. Gentle slopes with loam, light loam or bubble soil containing a small amount of gravel are most suitable for growing konjac. Before sowing in the konjac field, dig and turn the soil as early as possible to expose and aerate it, and remove stones, weeds and residual film from the soil.
Seed Corm Treatment
1. Seed corm production: To develop konjac production, the first step is to develop seed corm production and prepare enough seed corms. This includes disinfecting seed corms, separating seed corms from manure, applying timely chemical control, and promptly removing diseased plants. Developing seed corm production means insisting on propagating seed corms locally, mainly through farmers' own propagation. New growers must first develop seed corms, while established growers should allocate a corresponding area for seed corms. This improves the quality and safety of seed corms. The ratio of seed corms to field area is generally 1:3.
2. Seed corm disinfection: Disinfecting seed corms means eliminating pathogens on the seed corms at the source. First is sunning the seed: before sowing, spread the seed corms out in the sun for 2 days. Second is soaking the seed: on a sunny morning, soak the seed corms in a 500 ppm streptomycin sulfate solution for 30 minutes, remove and dry them, then sow immediately; or mix the seed corms with stove ash (wood ash), dry them and then sow. Where conditions permit, seed corms that have been sunned and soaked should be raised in a seedbed for sprouting and then transplanted to the field.
3. Sowing method: When sowing, keep seed corms and fertilizer separated from each other and never in direct contact. Use the method of first opening a sowing furrow and placing the seed corms, covering with soil, and then applying manure, to ensure safe emergence of the konjac seedlings. After the konjac emerges and before disease occurs, spray agricultural streptomycin or Mengkejun as a preventive protective treatment. Once a diseased plant appears in the field, choose a sunny day after the dew has dried, dig up the diseased plant together with its roots and the soil in the planting hole, bury it deep in a place far from cultivated land, and disinfect with lime. Never take diseased plants home to feed pigs as raw feed or discard them casually, as this causes artificial spread.
Scientific Fertilization
1. Fertilization principles: Konjac is a chloride-sensitive tuber crop with high fertilizer demands. It likes fertilizer and fears poor soil, and likes potassium and fears chlorine. It needs the most potassium fertilizer, followed by nitrogen fertilizer, then phosphorus fertilizer and trace elements such as calcium, zinc, magnesium and manganese. Therefore, it is essential to adhere to the principle of basing fertilization mainly on base fertilizer and heavily applying farmyard manure.
2. Base fertilizer management: For konjac fields with relatively low soil fertility, apply more than 2000 kg of farmyard manure per mu, such as bedding manure, high-quality soil-and-miscellaneous manure, or sod-and-fire ash. In the base fertilizer, apply 2-4 jin of biological potassium fertilizer according to soil nutrient status, and apply appropriate amounts of fertilizers such as urea and superphosphate or calcium magnesium phosphate.
3. Fertilizer selection: When fertilizing, it is strictly forbidden to use farmyard manure carrying diseased residues, chicken manure, or chemical fertilizers containing chlorine, and excessive nitrogen chemical fertilizer must not be applied. Applying large amounts of farmyard manure and as little chemical fertilizer as possible not only helps build soil fertility and improve the soil, but also enables konjac to grow steadily and robustly and enhances disease resistance.
4. Reasonable topdressing
① For the first seedling topdressing, when about 80% of the konjac has emerged, if the base fertilizer was insufficient, apply a heavy seedling fertilizer: per mu, use 20-30 dan of human manure and urine mixed with 40 dan of water for irrigation; if the base fertilizer was relatively sufficient, use about 5 jin of urea and 5 dan of human manure and urine mixed with water for irrigation.
② For the second topdressing, from late June to early July, mix high-quality farmyard manure such as bedding manure or fire ash with 6-8 jin of urea and 15-20 jin of potassium sulfate and spread it on the bed surface, combined with shallow earthing up.
③ For the third topdressing with tuber expansion fertilizer, from late July to early August, use 20-30 jin of potassium sulfate per mu, apply it in holes and cover with soil, and from August to September spray the leaves 2-3 times with a 0.2% potassium dihydrogen phosphate solution.
Field Management
1. Mulch management: After sowing konjac, vigorously collect mulch materials such as crop stalks, pod shells and dead leaves. Long ones are best chopped into pieces and spread evenly, firmly and tightly over the konjac field, meeting the standard of “no clumps of grass, no bare ground.” Generally about 2000 jin of mulch is needed per mu. After September, take care to remove unmulched material that has not decomposed.
2. Weed removal: Konjac roots are shallowly distributed. To prevent hoeing and weeding from cutting and injuring the developing young roots and underground stems and affecting normal plant growth, weeds can be pulled by hand. Note, however, that a person should only squat in the furrows to pull weeds and should not step on the bed surface, to avoid crushing and injuring the underground rhizomes.
3. Clearing furrows and earthing up: Konjac fears drought and also should not be waterlogged. Therefore, during the rainy season, especially after heavy rain, go to the field to inspect the planted plots, dredge the furrows and drain water to ensure the water channels are unobstructed. While clearing the furrows, cultivate the fine soil from the furrows onto the bed surface. Earth up 2-3 times during the growing period to facilitate corm formation and expansion, keep daughter corms from being exposed, and enhance konjac's wind resistance and resistance to lodging.
Pest and Disease Control
1. Soft rot
[Symptoms] It mainly affects leaf stalks, corms and leaves. After infection, the tissues turn black and soften and give off a foul odor, and can even cause the fruits to rot and lodge in patches, resulting in major losses.
[Control] Strengthen cultivation management for well-planted konjac, carry out deep plowing and land preparation, drainage and ventilation on a regular basis. When selecting seeds, carefully choose seed corms that are free of rot and wounds, and store and transport them properly. In addition, when planting, note that konjac should not be continuously cropped or intercropped with certain vegetable crops, such as those in the Solanaceae family. Before sowing konjac, it can be soaked in an appropriate proportion of agricultural streptomycin solution, then removed and dried.
2. Southern blight
[Symptoms] It mainly affects the base of the leaf stalk, thereby damaging the leaf stalk or corm. When the base of the leaf stalk is infected with southern blight, dark brown spots appear and continuously expand, eventually causing white silky mycelium to grow on the leaf stalk and take on a light red color.
[Control] For southern blight, strengthen field cultivation management and promptly drain standing water. When planting, do not practice continuous cropping or intercropping/successive cropping with peanuts, Solanaceae plants or soybeans. At the same time, an appropriate proportion of Bordeaux mixture can be used to spray and disinfect the area around where the leaf stalk contacts the soil surface during the period from konjac corm change to corm expansion.
3. Leaf blight
[Symptoms] It mainly harms leaves. The pathogen overwinters in the soil and can splash onto leaves with rainwater. It can also invade through wounds or stomata and spread through wind and rain. Therefore, the leaf blight pathogen has extremely strong infective ability, causing konjac to wither and die in patches.
[Control] The prevention and treatment measures for leaf blight are basically the same as those for soft rot.
4. Insect pests
[Symptoms] The main insect pests affecting konjac growth include sweet potato hornworm, konjac nematode, and bean hornworm.
[Control] To control these pests, it is necessary to clear weeds and dead leaves during winter and spring, and at the same time adopt the method of intercropping konjac with corn in the field, which plays an important role in pest control. In addition, insecticides can be used manually to eliminate pests, and when using farmyard manure, be sure to choose thoroughly decomposed farmyard manure.