Detailed Explanation of Cultivation Techniques for Artificial Pond Lotus Root

I. Selecting Varieties

Seed lotus roots are generally dug up just before planting, selecting whole lotus roots or larger daughter lotus roots that have typical varietal characteristics and a relatively thick rear stem node (i.e., the lotus tail). The daughter lotus roots on the whole lotus root must grow in the same direction, so that the extending lotus runners elongate in an orderly manner. If daughter lotus roots are used as seed, they must have at least two or more fully mature lotus root sections, with intact terminal buds, cut at 1.5 cm behind the second node stem; never snap them off by hand, to prevent muddy water from entering the lotus root holes and causing rot. The main varieties of seed lotus roots include early-maturing varieties Hua Ou, E Lian No. 1, No. 3, etc., and mid-to-late-maturing varieties Mei Ren Hong, Da Zi Hong, E Lian No. 2, etc. Seed lotus roots should be dug, selected, and planted in sequence; if they cannot all be planted the same day, sprinkle water and cover them to retain moisture. Prevent leaf buds from drying out and withering. In early-maturing cultivation of lotus root, sprouting is generally promoted first, to prevent rotting seeds and missing plants caused by planting too early in frost, water temperature being too low, and late frost damage. The method for promoting sprouting is: place the seed lotus roots in a warm room, with rice straw spread above and below, sprinkle water 1-2 times daily, to maintain 20-25°C and relative humidity of about 75%; after about 20 days, when buds are about 10 cm long, they can be planted.

II. Cultivation Techniques

1. Lotus pond construction. Dig down 40 cm on flat ground, and use the excavated soil to build a 40 cm-high earth ridge along the pond edge. Build the edges with cement blocks around the perimeter, and use plastic film to line the pond and the earth ridge, to prevent water leakage. Then spread wheat straw or corn stalks evenly in the pond, at a thickness of 40 cm. Wheat bran can also be used, spread at a thickness of 20 cm. Cover the evenly spread straw with 10 cm of soil; the soil layer must be spread evenly. In combination with pond lotus root, apply 2000-3000 jin of organic fertilizer and 30 jin of compound fertilizer per mu; prepare the land so that the mud is soft, the field is level, and fertilizer is sufficient.

2. Planting seedlings. The seeding rate per mu is 400-500 jin, with a plant spacing and row spacing of 0.7 x 1.5 m. When planting, insert the lotus root bud head obliquely into the soil to a depth of 10-12 cm; the bud head should be parallel to the soil surface, and the rear stem node should be exposed 2-3 cm above the ground. For lotus roots planted around the field perimeter, the bud heads should face inward, to prevent the lotus roots from growing out of the field plot. Within the field, use staggered cross planting; the bud heads should not all face one direction, to help make full use of the field space. Cover the seed lotus roots lightly with soil, just enough so they do not float up after irrigation. After planting the seed lotus roots, irrigate to 5-10 cm above the soil.

III. Management Techniques

1. Water layer management. The principle of water layer management is shallow-deep-shallow, that is, only a 2-3 cm shallow water layer is needed at the initial planting stage, until the first standing leaf growth period about one month later around May 20; in July-August, a water depth of 15-20 cm is needed, and if there are storms, deep water of 50-80 cm can be irrigated briefly. In the late growth stage, only a 7-8 cm shallow water layer is needed, and shallow water is used for overwintering.

2. Topdressing. During the growth period, topdress a total of three times. The first is at the standing leaf stage, around May 20, applying 2000-3000 jin of human excrement and urine and 10-15 jin of urea between the rows; green manure can also be applied at this time. The second is from June 20 to early July, applying 40 jin of urea and 60 jin of compound fertilizer per mu. At this time, be careful to prevent stepping on lotus root heads when entering the field, and fertilizer must not be applied on the leaves. The third is from July 15-20, depending on the growth situation, fertilizer can be applied appropriately; if growth is poor, apply 10-15 jin of urea, 40 jin of compound fertilizer, 40 jin of superphosphate, and 1000 jin of plant ash per mu.

3. Pests and diseases. Field lotus roots have relatively few pests and diseases, and they are found only in old lotus root fields. Generally there are aphids, Spodoptera litura, root-eating Donacia beetles, rot disease, viral disease, brown spot disease, etc. The control methods are the same as those for vegetable fields, except that an additional pesticide sticker (washing powder, detergent) needs to be added.

4. Water layer regulation and chemical weeding. According to the adaptability of lotus root to water level, it can be divided into two ecological types: shallow-water lotus root and deep-water lotus root. Shallow-water lotus root is suitable for a water level of 10-20 cm, with a maximum water depth tolerance of 30-50 cm. Deep-water lotus root is suitable for a water level of 30-50 cm, with a maximum water depth tolerance of 1-1.2 m.

The general principle of water layer management for shallow-water lotus root is: shallow at the front, deep in the middle, shallow at the back. During the sprouting growth period after planting lotus root until standing leaves appear, shallow water should be maintained to increase soil temperature and promote germination. Generally, maintaining a water layer of 4-7 cm deep is best. With the appearance of standing leaves, the stems and leaves of lotus root gradually grow vigorously, and the water layer should gradually rise to 12-15 cm. When terminal leaves appear, it indicates that lotus root formation has begun, and the water layer should gradually be lowered to 4-7 cm to promote lotus root formation. The water level of deep-water lotus root is not easy to regulate; the main thing is to prevent waterlogging during the flood season, especially after standing leaves are submerged, emergency drainage should be carried out within 8 hours to make the lotus leaves emerge above the water surface, to prevent drowning. During the growth process of lotus root, especially in the early growth stage of shallow-water lotus root, weeds such as Potamogeton, Heleocharis, dwarf arrowhead, Scirpus, Marsilea quadrifolia, and Hydrilla are relatively numerous in the paddy field and grow quickly, affecting lotus root growth, so weeds should be removed promptly. In the past, manual intertillage and weeding were often used, which required a large workload and easily injured the underground stem buds of lotus root by stepping on them. If chemical weeding is used, it saves labor and effort, and causes no harm to lotus root. Safe and effective chemical weeding methods can be used. The specific methods are:

(1) Choose 50% Wiloson emulsifiable concentrate; when the standing leaves of lotus root grow 30 cm above the water surface, take 100 milliliters of the pesticide, first mix with 5 kg of urea, then add 5 kg of fine soil, mix thoroughly, and broadcast it in the field when the dew has dried. When applying the pesticide, keep the lotus field water depth at 7-10 cm, and maintain the water layer for more than one week after application; the effect is good, and the residual effect period can reach more than 1 month.

(2) Topdress when lotus stems grow to 50 cm. Apply 50 kg of nitrogen-phosphorus-potassium ternary compound fertilizer per mu. If leaves later turn yellow, apply urea once more, at 15 kg per mu.

IV. Harvesting and Lotus Root Storage Techniques

When harvesting, simply hold one end of the lotus root branch and lift it upward along the growth direction, and the entire lotus root plant can be lifted out of the water, saving both labor and effort. It can also be harvested according to market conditions; generally, it can be harvested after the end of August.

Lotus roots for storage must be strictly selected as underground stems that are free of disease and injury, firm in texture, thick in lotus root flesh, and low in water content; after harvesting, do not wash them, and store the whole roots with mud on the surface. They can be stored in a shallow pit dug indoors, covered with rice straw or soil. Or they can be layered with dry sand in a storage warehouse, with the surface covered with 5-10 cm of sand. The covering must not be too thin, otherwise the bulbs in the surface layer are prone to dehydration and loss of freshness. If humidity is too high, they are prone to rooting, mold, and rot. According to experiments, in a cold storage warehouse at 5-7°C (maximum 11°C) and in an ordinary underground room (9-14°C in winter, 23-25°C in summer), using dry sand burial, no obvious difference in effect was seen between the two. Sealed storage in plastic bags is not as good as sand burial, and is prone to mold, rooting, and browning.