Detailed Explanation of Key Techniques for Straw-Based Cultivation of Lotus Root in Shallow Ponds

Straw-based cultivation of lotus root in shallow ponds gives high yields, is easy to harvest, saves water and labour, and the planting area is expanding year by year. The average yield is 4000 kg of lotus root per mu, more than 30% higher than that of ordinary shallow-pond lotus root.

1. Choosing suitable varieties. For seed lotus root, choose early-maturing varieties with thick, round rhizomes, white skin, crisp and tender flesh, sweet taste, good quality and high yield, such as 'Elian No. 4', 'Elian No. 5', 'Jinan White Lotus Root', etc.

2. Building the lotus pond

1. @#@185@#@Material preparation: the lotus pond should be chosen in a sunny place without shade from trees, such as village-edge wasteland, abandoned house sites, disused pits and ponds, low-lying abandoned land, etc. Building one mu of lotus pond requires 5 tonnes of lime, 5 tonnes of cement, 30 tonnes of sand, 800 sq m of 8-gauge polyethylene plastic film, and 230 cement precast blocks measuring 70 cm x 50 cm x 5 cm (length x width x thickness). The total cost per mu is about 5000 yuan.

2. Building the pond: the pond depth is 60 cm, and the slope of the pond walls is 60 degrees. Spread lime on the pond bottom, rotary-till it 2-3 times to a depth of 20 cm, and after the soil and lime are mixed evenly, level and compact the pond bottom with a tamping machine. Tamp the pond walls firm with 3:7 lime soil, lay the film smoothly over the pond bottom and walls, then apply a 2-3 cm thick layer of concrete, stand the prepared sloping boards against the pond walls, and seal the joints with cement. The completed lotus pond can be used for 15 years.

3. Land preparation and fertilisation. Spread rice straw, wheat straw, corn stalks or weeds into the pond to a thickness of 30-40 cm; 15,000 kg of straw is needed per mu. Mix 5000 kg of farmyard manure, 50 kg of diammonium phosphate and 50 kg of potassium sulphate evenly with the covering soil, then cover the straw with it to a thickness of 12-15 cm.

4. Selection and arrangement of seed lotus root. Dig up the seed lotus root just before planting, and select whole rhizomes that conform to the characteristics of the variety and bear daughter rhizomes as seed stock; the daughter rhizomes must grow in the same direction. Cut the seed lotus root 1.5 cm behind the second node, spray it with a 500-fold dilution of 50% carbendazim or a 600-fold dilution of chlorothalonil, and keep it covered for 1 day before use; it can also be sterilised by soaking for 30 minutes in a 500-fold dilution of 50% carbendazim.

Arrange the lotus root between Qingming and Guyu. Use 300 kg of seed lotus root per mu, with a row spacing of 1.5-2 m and a plant spacing of 0.6-1 m. When arranging, bury the growing tip of the lotus root 12-15 cm deep in the straw, with the rear node slightly tilted above the water surface to use sunlight to promote sprouting. Arrange the plants in a triangular staggered pattern so that the lotus runners are distributed evenly. Along the four edges, point the growing tips towards the inside of the pond so that the runners do not extend beyond the banks. After arranging the lotus root, irrigate to a depth of 4-5 cm.

5. Field management

1. Weeding, leaf removal and flower snapping: weed when floating leaves appear half a month after planting. One month after planting, when the floating leaves gradually wither, remove them so that sunlight can penetrate the water and raise the water temperature. Once standing leaves cover the water surface, do not enter the field to weed again, so as not to bruise the lotus root. After buds appear, bend the flower stalks and insert them into the mud.

2. Topdressing: topdress twice during the growing period. The first topdressing is when the lotus has produced 5-7 standing leaves and entered the period of vigorous growth; apply 1000-1500 kg of manure per mu, or 10 kg of diammonium phosphate and 10 kg of potassium sulphate. The second topdressing is at the root-forming stage; apply 50 kg of compound fertiliser (NPK) per mu. Topdressing should be done on a windless sunny day; drain to shallow water before fertilising, and after the fertiliser has been fully absorbed into the soil, refill to the original water level. After topdressing, splash clean water to wash the lotus leaves.

3. Water level regulation: at the early stage of planting, maintain shallow water of 4-7 cm; during the period of vigorous growth, gradually deepen the water layer to 12-15 cm as the standing leaves and branches grow vigorously; at the root-forming stage, it is best to maintain shallow water of 4-7 cm.

4. Turning the lotus runners: when the curled leaves are 1 m from the pond edge, at any time turn the runner tips near the pond edge back towards the inside of the pond so that the forming rhizomes are distributed evenly. During the peak growth period, turn them once every 2-3 days; during the slow growth period, turn them once every 7-8 days, for a total of 5-6 times. Turning is best done at noon when the stems and leaves are soft; simply lift the runner tip and bury it in the soil in the direction of turning.

5. Pest and disease control: the main disease of lotus root is rhizome rot, which mainly attacks the underground stem of the lotus, causing it to turn brown and rot and leading to withering of the above-ground parts.

Control methods: (1) disinfect with lime before arranging the lotus root; place 50-70 kg of quicklime lumps per mu of lotus pond; (2) if disease occurs during the growing period, promptly pull out diseased plants and spray the whole field with a mixture of a 600-fold dilution of 50% carbendazim plus a 600-fold dilution of 75% chlorothalonil, or mix equal amounts of the above two fungicides, and per mu use 500 g mixed with 25 kg of fine soil, pile and cover for 4 hours, then scatter it into the pond, once every 5-7 days, for 2-3 consecutive treatments. The main insect pests are aphids and tobacco cutworms; aphids can be controlled with imidacloprid, pirimicarb, etc., and tobacco cutworms with pyrethroid pesticides, chlorfluazuron, flufenoxuron, etc.

6. Harvesting. After October, lotus root can be harvested at any time as needed. Because straw-based cultivation in shallow ponds is used, harvesting is convenient; simply grasp the lotus root and pull it out slowly.