Experience Sharing on Integrated Rice and Crayfish Farming

With the continuous development of China's aquaculture industry, crayfish farming is now very common. There are many methods for farming crayfish in China, and different farmers adopt different methods, so farmers can exchange and learn from one another.

Staggered Cropping Schedule for Crayfish Farming

Continuous cropping model - after the rice is harvested in late September, water is let in to flood the field, and crayfish fry are released into the paddy field to reproduce on their own, then caught and sold to market from May to early June of the following year. For rice planting, starting on May 10, separate seedling beds are selected for raising seedlings, and transplanting takes place around June 15.

Co-cropping model - in the later stage of the rice-crayfish continuous cropping cycle (before transplanting in early June), crayfish in the paddy field that have not reached market size are kept in the field so they grow together with the transplanted rice. Egg-bearing parent crayfish are released from August to October of the previous year; they are not all harvested in May of the current year, and the remaining crayfish are kept as seed stock for the following year; in March of the following year, fry are supplemented appropriately according to juvenile crayfish density. No-till seedling-throwing technology can be used for the rice, and harvesting takes place in mid-August.

Crayfish Management Techniques

1. Ditches and furrows. Seedling disinfection - the ditch water depth is about 1.8 m. For disinfection, bleaching powder plus quicklime is used, at 5-6 jin per mu, sprinkled once every half month. After long-distance transport (Shen Songming's crayfish fry are purchased from Wuhan, Jianyang and Ziyang), the fry are more prone to diseases such as gill rot and ciliate disease, so they need to be soaked and disinfected in 3% salt water for 3-5 minutes. The soaking time is adjusted flexibly according to the water temperature that day and the tolerance of the fry.

2. Planting aquatic plants. When crayfish have balanced, comprehensive and high-quality nutrition, they molt more frequently; if they cannot molt successfully, they will die. In addition, crayfish prefer shade and fear light, so besides the rice seedlings, a certain amount of aquatic plants can be planted in the crayfish ditch to provide shade, shelter and molting sites, and to prevent aggressive crayfish from cannibalizing one another. Aquatic plant coverage of 5%-10% of the ditch surface is sufficient.

3. Feeding management. Crayfish will kill and eat one another when hungry, so the amount of feed must be sufficient. Plant-based feeds include wheat, aquatic plants and rapeseed cake, while animal-based feeds include miscellaneous fish, miscellaneous meat and livestock offal. The feeding time, amount and method are determined according to the crayfish's habit of hiding by day and emerging at night and the density of crayfish in the pond. Otherwise, feed costs will increase. Shen Songming suggests that when the first batch of fry is released, natural food can be the main source, and once the new generation of fry hatches and the total number increases, artificial feed can be added. At present, special crayfish feed costs 8,000 yuan per ton, while Shen Songming mostly uses his own blend of bran, corn, distillers' grains and green vegetable leaves, which reduces feeding costs by 50% and still gives good results. For the rice, Shen Songming applies pig manure and rapeseed meal, and the small insects bred by the latter are a delicacy for the crayfish. The feeding amount is based on there being no leftover bait the next day, with specific adjustments made as appropriate according to weather, changes in water quality, and the feeding and activity of the crayfish.

4. Daily management. During pond patrols, check whether the crayfish farming ditch and the inlet and outlet facilities are intact, to prevent crayfish from escaping. During the farming process, the pond water pH should be kept between 7.5 and 8.5, and the transparency at 30-40 cm. New water should be added frequently, and quicklime solution should be sprinkled regularly to regulate water quality and prevent disease and incomplete molting.

5. Bird nets. The natural enemy of crayfish is the white-throated bird, and currently mainly intimidating methods are used to drive them away. In addition, advantage can be taken of the fact that birds' stereoscopic vision range is only about 10 degrees, by stringing transparent nylon lines every 20-30 cm across the farming paddy field to block birds from foraging for crayfish.

Crayfish Paddy Field Farming Technology  

1. Paddy field selection  

For the paddy field, it is best to choose loam with abundant water sources, good water quality, a quiet surrounding environment, convenient drainage and irrigation, and convenient transportation. The water source should be a large water body free of pollution; the field should not be affected by drought or flood disasters, the water quality should be fresh and pollution-free, the soil should be fertile but not silty, and the field ridges should be high (able to hold a water depth of 40-60 cm) and solid, not leaking water, with good water retention and plenty of sunlight.  

2. Field engineering construction  

Field construction mainly includes widening, raising and reinforcing the field ridges. Filtering and anti-escape facilities are installed at the inlet and outlet, ring ditches and field ditches are excavated, and shade sheds are installed, etc. A ring ditch is dug around the paddy field as a crayfish farming ditch, ensuring the ring ditch is 3-5 m wide and 1.0 m deep. For larger fields, a field ditch in the shape of the character "" or "" should also be dug in the middle, with the field ditch being 1.0 m wide and 0.5 m deep respectively. The area of the ring crayfish farming ditch and the field ditch accounts for about 10% of the paddy field area.

Conditions for Building Paddy Field Crayfish Farming  

Choose a field with good water quality, abundant water, no pollution sources nearby, strong water retention capacity, convenient drainage and irrigation, and no risk of flood submersion for paddy field crayfish farming. The area can be as little as a few mu, or as much as dozens of mu or over a hundred mu. A crayfish farming ditch should be dug along the inner side of the field ridge around the paddy field, with a ditch width of 1.5 m and a depth of 1 m. For larger fields, a field ditch should also be dug in the middle of the field, with a field ditch width of 1 m and a depth of 0.5 m. The crayfish farming ditch and field ditch together account for about 20% of the total paddy field area.  

Use the soil dug out from the crayfish farming ditch to reinforce and raise the field ridges and level the field surface. When reinforcing the field ridges, each layer of soil added must be tamped down to prevent the ridge from collapsing during heavy storms. The ridge surface width should be more than 3 m and the ridge height 1 m. The inlet and outlet should be enclosed with wire mesh or fencing to prevent crayfish from escaping and natural enemies from entering. The inlet channel is built on the field ridge, and the outlet is built at the lowest point of the crayfish ditch, following the pattern of high-level irrigation and low-level drainage, ensuring water can flow in and drain out.  

At a distance of 1 m from the field ridge, drive a 1.5 m high post every 3 m, set up with moso bamboo, and plant melons, beans, gourds, etc. along the edge of the field ridge. Once the vines climb the trellis, they provide shade and relief from the heat in the hot summer. Aquatic plants such as Vallisneria, Hydrilla verticillata and Ceratophyllum demersum should be transplanted into the crayfish farming ditch and the field, with aquatic plant coverage of about 30% being appropriate, and it is best to have them scattered and dispersed, which helps the water flow in the crayfish ditch stay unobstructed. Build an anti-escape wall around the field with plastic film, cement board, asbestos tile or calcium-plastic board to prevent crayfish from escaping.

This model of farming crayfish in paddy fields is currently the most common and most commonly used farming model in crayfish farming. It achieves the method of using one field for multiple purposes and creates greater profits. Therefore, this combination of planting and farming is relatively popular among people at present.