New high-yield techniques for lotus root: straw-fed lotus cultivation and lotus-fish polyculture

In April 2006, the Yindu Industry, Trade, Science and Technology Ecological Park in Wenshang County, Shandong Province, was completed and put into operation. Using waterlogged, saline-alkali and barren land, through scientific methods and the implementation of multi-component composite three-dimensional development, a science and technology ecological park was built integrating vegetable and forage cultivation - livestock and poultry breeding - straw-fed lotus cultivation - fish farming in lotus ponds @#@233@#@ - fishing and leisure - dining and entertainment, and other functions into a circular economy development model, achieving remarkable economic and ecological benefits. In particular, the new corn straw-fed lotus cultivation technique promoted by the park can achieve a lotus root yield of up to 6000 kg per mu, which is 3 to 4 times the yield of traditional lotus cultivation. Many farmers used to simply burn their corn straw, which not only polluted the air and affected health but also wasted resources. The new straw-fed lotus cultivation technique solves this problem: cultivating one mu of lotus requires the corn straw produced from 30 mu of land. In this way, straw can be turned from waste into a valuable resource. In addition, fish farming in lotus ponds is an optimized model for developing ecological fisheries, enabling three-dimensional development of resources, comprehensive utilization and energy conservation. Some of the practices are introduced below:

I. Lotus pond construction

In mid-to-late March, select a plot with flat terrain, fertile soil and strong water retention. Build ponds with bricks and cement, each unit measuring 30 m east-west, 15 m north-south, and 90 cm deep (40 cm above ground, 50 cm below ground), giving 450 sq m per unit. Coat the inner and outer walls with cement to prevent seepage. Build them in a continuous series with a distance of 25 cm between ponds. After construction, harden the pond bottom with lime and soil mixed in proportion.

II. Straw laying

In early April, after the cement ponds have dried, tie corn straw of uniform specifications and length into bundles with rope. Lay them in a crisscross pattern in an east-west direction, with each 4 to 5 sq m as one unit. The straw thickness should be 25 cm to 30 cm. Then backfill with 25 cm to 30 cm of soil mixed with chicken manure. Mix the chicken manure and soil together for backfilling. Apply 5 to 8 cubic m of chicken manure per mu. Other fertilizers can be applied according to specific conditions.

III. Lotus seed cultivation

Lotus seeds are required to be fresh, without cuts or broken shoots. Generally, plant 250 kg to 350 kg of lotus seeds per mu (this park selected the high-quality, high-yield E'lian No. 10 lotus seed). When placing the lotus seeds, follow the direction of the straw laying and insert the seeds diagonally into the straw layer, thereby improving the soil structure at the bottom of the pond and promoting the expansion of lotus rhizomes. In addition, combined with carbon dioxide straw gas fertilizer yield-increasing technology, inoculate a certain proportion of carbon dioxide gas fertilizer bacterial strains into the straw layer, so that it releases a large amount of carbon dioxide gas, fully meeting the growth needs of the pond lotus and greatly increasing the lotus root yield. The crisscross placement of straw in the pond can block lotus shoots from spreading randomly throughout the pond. Because when lotus shoots grow in the pond, they only begin to form lotus roots when they encounter an obstruction. This is the key to straw-fed lotus cultivation and also the reason why the yield can be several times higher than ordinary lotus cultivation. In addition, after soaking and fermenting in the pond, the straw can also be converted into organic fertilizer for lotus growth, which is also one of the factors contributing to increased lotus yield.

IV. Fish fry stocking

In late April, when the lotus has grown leaves, 7 to 8 days before stocking fish, splash quicklime milk at a concentration of 20 ppm along each pond for disinfection. After the toxicity has dissipated and the water temperature remains above 17°C, begin stocking fish fry. Before stocking, soak the fry in 2% to 3% salt water for 5 to 10 minutes, or in a 4 ppm copper sulfate solution for 10 to 15 minutes, adjusting flexibly according to the fish's tolerance. Select healthy, disease-free, uninjured rice field eels of uniform size with yellow backs and dark brown spots for stocking. The specification is about 30 eels per kg, with 300 to 500 eels stocked per mu. Loach fry should be 0.5 g each, as uniform in size as possible, with 600 to 800 stocked per mu. Appropriately stock silver carp and bighead carp at 10 to 15 fish per kg, with 500 to 700 stocked per mu. Around June, stock additional summer fry of silver carp and bighead carp at 1000 to 2000 per mu as live bait for the eels and loaches.

V. Daily management

1. Feeding management: When feeding, ensure fixed quality, fixed quantity, fixed timing and fixed location. Generally feed twice a day, from 7:00 to 8:00 in the morning and from 15:00 to 17:00 in the afternoon. @#@236@#@ Animal-based feed should be dominant, such as @#@254@#@, @#@261@#@, small fish, shrimp, yellow mealworms or pig and poultry internal organ scraps; plant-based bait should be supplementary, such as soybean cake blocks, wheat bran, duckweed, tofu workshop scraps or compound feed. The feed must be fresh; spoiled feed must not be given. For newly stocked eel fry, feed small animal-based bait first, and after domestication, feed compound feed. In lotus ponds, it is advisable to stock eel fry first, and after they have adapted to compound feed, then stock loach fry. If eel fry and loach fry are stocked at the same time, it will certainly affect the domestication of the eels. @#@237@#@ Plant-based feed should be dominant, such as aquatic plants, vegetable leaves, rice bran and soybean cake, supplemented with animal-based bait and compound feed, with a feeding amount of 5% of body weight. For silver carp and bighead carp, regularly splash fermented manure water into the lotus pond to cultivate plankton as bait, splashing 50 kg to 100 kg of manure water per mu each time, while also providing high-quality plankton bait for the loaches.

2. Water quality management: Suitable water temperature is the main factor for the joint growth and yield increase of lotus and fish. Generally, the water level should be maintained at about 30 cm, which is conducive to the growth and development of lotus and fish. If the water surface is too deep, the lotus cannot obtain a suitable growth temperature; if too shallow, it is not conducive to fish growth. Therefore, it is necessary to observe the water level, add water in a timely manner and regulate water quality.

3. Anti-escape facilities: At the end of June, before the flood season arrives, anti-escape facilities should be installed to prevent fish from escaping due to pond overflow. Window screen or polyethylene netting can be used (note that the mesh should not be too large, so that fish cannot escape). Enclose a ring along the pond edge at a height of 60 cm. Every 1 to 2 m, use a thin bamboo pole to support the window screen or polyethylene netting, and cover the bottom of the bamboo poles with soil and press firmly.

4. Disease prevention and control: Adhere to the principle of "prevention first, combining prevention and treatment." Splash quicklime milk over the entire pond once every 15 to 20 days at a concentration of 20 ppm. Implementing ecological co-cultivation of eels, loaches, silver carp, bighead carp and lotus helps adjust the multi-component composite breeding structure, improve the water environment, and achieve good ecological disease prevention, so diseases generally do not occur easily. At ordinary times, pay attention to preventing and treating common diseases of eels and loaches, such as putrid skin disease, saprolegniasis, tail rot disease and capillary worm disease. In the early growth stage, also pay attention to strengthening patrols and driving away water birds, rats, frogs, snakes and other biological enemies.

VI. Timely harvesting

Silver carp and bighead carp can be harvested from "Autumn Equinox" to "Winter Solstice," generally yielding 150 kg to 200 kg per mu. From September onward, eels and loaches can be caught using tools such as eel cages; before overwintering, they can be harvested by turning over the mud block by block with both hands. If they are to be kept for sale around the Spring Festival, freeze prevention work must be done during the overwintering period, and if necessary, drain water and cover for freeze protection. If overwintering with water, the water layer must not be too shallow to prevent freezing. After stocking, rice field eels can grow to 30 cm to 40 cm after 3 months of rearing. Generally, about 160 kg of eels and loaches are caught per mu, and the average lotus root yield per mu is 4000 kg to 6000 kg. The total annual income from lotus root and polycultured fish can reach an average net benefit of 8000 yuan to 12000 yuan per mu, an increase of 50% to 70% compared with single planting or single rearing.

VII. Analysis and discussion

1. The yield of straw-fed lotus in cement ponds is 3 to 4 times that of traditional lotus cultivation. The key lies in changing the pond structure. Cement ponds are easy to manage and help raise water temperature, and can be reused for more than 10 years, reducing repeated construction and saving costs; when building them, they should not be too large or too small.

2. Laying straw and planting lotus in a "I"-shaped pattern according to the direction of the straw conforms to the growth habits of lotus. In addition, straw provides insulation and ventilation, facilitates lotus harvesting, and can serve as fertilizer after rotting, which is also one of the main factors in increasing lotus yield.

3. Adhere to the principle of "lotus as the main crop, fish as the secondary." Appropriately regulate fish density. Single-species rearing can also be practiced, but it is not advisable to stock too many, because the shading of lotus leaves often prevents the water temperature from reaching the required level, so that the fish cannot reach market size and directly affect economic benefits.

4. Developing straw-fed lotus cultivation can not only greatly increase the yield and benefits of pond lotus, but also consume large amounts of crop straw, turning crop straw from waste into a valuable resource. It can avoid the resource waste and environmental pollution caused by straw burning, and can also drive the development of the rural local economy. It is a practical new vegetable cultivation technique for building a new socialist countryside and promoting increased farmers' income.