Some models of green-legged shrimp farming - rice

Winter-spring rice and giant freshwater prawn

This model can be implemented in flooded areas, where summer-autumn rice cultivation is unstable and autumn-winter rice cultivation is difficult, or where summer-autumn rice production is ineffective.

Season: The giant freshwater prawn farming season usually starts in March - April (DL) and lasts until the beginning of the winter - spring rice crop. The shrimp farming season lasts 7 - 8 months, so the harvested shrimp size is large (large size), can be sold at a good price and is suitable for releasing baby shrimp (Pl 15).

Farming field design: Farming field area can vary depending on specific conditions, usually from 0.5 to 4 hectares. The field must have a surrounding ditch, accounting for 20 - 25% of the total field area. The ditch is 2 - 3 m wide and 0.8 - 1.0 m deep compared to the field surface.

The bank is 1 - 1.2 m high (or higher than the flood peak), the foot of the bank is 3 - 4 m wide. During the main flood season (when the flood is at its highest), it is necessary to cover the bank with a net 30 - 50 cm high to prevent shrimp from escaping.

Preparing fields and nursery ponds: After harvesting the winter-spring rice crop, prepare the nursery fields, such as: repairing pond banks, dredging mud in surrounding ditches; then apply lime at a dose of 150 - 200 kg/ha and dry the fields for 3 - 5 days before taking water.

Fields with newly dug ditches or alum need to be washed 2-3 times before lime is applied.

Water supply: Fill the pond with water to cover the field surface by 30 - 40 cm or 0.8 - 1 m for nursery ponds and apply 30 kg of organic fertilizer or 0.5 kg of urea + 1 kg of NPK (or DAP)/1,000 m2 to color the water. After 3 - 5 days of fertilizing, when the water turns green, release the shrimp.

Breed and stocking density: This model is suitable for stocking Pl 15 shrimp (size 0.020 - 0.025 g/shrimp) because of the long rearing time. Stocking density is 3 - 5 shrimp/m2 of field.

Shrimp rearing: Shrimp larvae should be reared 3-4 weeks before being released into the field, to limit loss and make it easier to care for when the shrimp are still small. Shrimp larvae can be reared in ponds, part of the field or ditches (5-10% of the total area). Use mosquito nets, plastic sheets, etc. to block the ditches for rearing shrimp.

Food and feeding: During the nursery period, feed the shrimp with high quality food, such as industrial food or fish meal, at 10 - 20% of body weight.

During the growing stage, use industrial or homemade food, but ensure adequate nutrition.

During flood season, natural food is abundant, you can use fresh food (such as fish, snails, shrimp...) to reduce costs.

Care and management of farming fields: During the pre-flood period from April to July (DL), it is necessary to maintain a good farming environment for shrimp to grow quickly: change water regularly, manage the environment, and feed adequately and appropriately. When the flood comes, it brings a lot of food but can also affect water quality and shrimp health; therefore, it is necessary to pay attention to effective care and prevention measures.

Harvesting: There are many harvesting methods. Female shrimp can be harvested after 4 - 5 months of stocking or harvested once at the end of the farming season (November DL) before sowing winter-spring rice. This model can achieve a yield of 750 - 800 kg/ha/crop.

Two rice crops and one shrimp crop combined

This model is suitable for areas where summer-autumn and winter-spring rice can be cultivated; similar to the above model but shrimp can be raised in combination with summer-autumn rice for 3 months.

Season: Shrimp farming season starts with the summer-autumn rice crop or 1 month after sowing/planting the summer-autumn rice crop and lasts until the beginning of the winter-spring rice crop.

Farming field design: The field has an area of ​​0.5 - 4 hectares, designed similar to the winter-spring rice and giant freshwater prawn model above.

Field preparation: After harvesting the winter-spring rice crop, prepare the field for sowing/transplanting the summer-autumn rice crop. For summer-autumn rice, follow the rice cultivation process; in addition, it is necessary to repair the pond banks and ditches for shrimp farming.

Because rice farming must be done according to the crop schedule, while shrimp farming depends on the source of shrimp seed, rice is usually sown before shrimp are released. Rice should be sown/planted in rows so that shrimp can go to the fields to find food more easily.

After sowing rice, lower the water level in the ditch and add lime to the ditch at a dose of 150 - 200 kg/ha to remove alum and kill bacteria. After 2 - 3 days, add fertilizer to color the water. Dosage: 30 kg of organic fertilizer/1,000 m2 or 0.5 kg of urea + 1 kg of NPK or DAP fertilizer/1,000 m2. After 3 - 5 days, release shrimp when the water color is good.

Seed source and stocking density: Should stock shrimp Pl 15 - Pl 20. Density 3 - 5 shrimp/m2. Shrimp larvae need to be nursed for 3 - 4 weeks before stocking.

Food and feeding: Food, feeding methods for nursing shrimp, shrimp for meat, and management of farming fields are similar to the winter-spring rice and giant freshwater prawn models. However, in this model, if pesticides must be sprayed on the rice during the farming period, the water must be lowered to let the shrimp go down the ditch. After 3-4 days of spraying (when the pesticide has worn off), the water can be raised again.

When harvesting rice, lower the water so the shrimp can go down the ditch. After harvesting the rice, raise the water so the shrimp can go up to the field to eat food, the shrimp will grow faster.

Harvesting: Female shrimp can be harvested after 5-6 months of rearing, from the day of stocking. For this model, it can be harvested at the end of the rearing season (end of November) before planting winter-spring rice.

This model's productivity reaches 350 - 550 kg/ha.

According to (NNVN)