Single-season late rice thin-shell field snail composite breeding technology
_Kim Hye-fong
In 2016, in order to stabilize the area of grain planted, improve the output of rice fields and increase the income of farmers, the agricultural technology department of Keqiao District of Shaoxing City carried out a single-season late rice thin shell field snail composite breeding experiment, covering an area of 45 mu. After 4 years of testing, the composite breeding technology of single-season late rice thin shell field snail is becoming more and more perfect, and in 2019, the average output value per mu is 4158 yuan and the net profit is 1556 yuan. The series of single-season late rice thin-shell field snail composite breeding techniques are briefly described below.
1. Construction of fields
One year in advance, the surrounding non-industrial and mining enterprises, adjacent to the clear river water, drought does not dry, flooding, fertile soil plots are selected as composite planting and breeding land. In late January of the first year of the compound breeding, the rice field was deeply turned 0.50m, and the soil characteristics were improved by freeze-thaw weathering. In late February, the north-south direction of the demarcation of the planting and breeding area, the length and width of 80m× 25m, the area of 3 acres. Dig a large ditch with a width of 0.7m and a depth of 0.3m around each cell, and dig a small ditch of 0.4m wide and 0.2m deep at the long side of 20m, 40m, 60m and 10m wide. Build a field 0.5m wide and 0.3m higher than the field surface around the community, consolidate and strengthen the field, and then lay a thickness of 0.075mm polyethylene without drip film waterproof leakage. In early March, 15 kg of calcium superphosphate, 10 kg of potassium sulfate and 3500 kg of mixed fertilizer of pig manure, sheep manure and duck manure after high-temperature fermentation were applied to the single-season late rice base fertilizer and thin shell field snail base bait, and then shallowly overturned the soil. In mid-March, the quicklime slurry is evenly sprinkled on the field, the field is disinfected and removed from the small miscellaneous fish, small miscellaneous snails and thin shell field snails, and 60 kg of quicklime is used per mu.
Second, thin-shelled field snails are fed in the early stage
(1) Release snail seedlings.
At the end of March, a sunny morning is selected, the field block is irrigated to 0.20m above the field surface, and the water level naturally decreases; the next morning, the field block is irrigated again to 0.20m above the field surface, and in the afternoon, the snail seedlings weighing about 1.5g are selected with light brown color, no damage to the shell, no ant and other parasites, and are evenly placed on the field block, about 7000 per mu, 10.5kg; after that, the water level is lowered to 0.10m above the field surface, and this water level is maintained until the single-season late rice sowing.
(2) Feeding bait.
The feeding amount of thin-shelled snails is related to its ambient temperature, the water temperature is 20-28 °C, the appetite is strong, and the feeding is stopped when the water temperature is lower than 15 °C or above 32 °C. After the snail seedlings are released, if the maximum temperature of the day is lower than or equal to 15 °C or higher than or equal to 32 °C, the bait is not fed; if the maximum temperature of the day is between 15-20 °C or 28-32 °C, at 8 a.m. every day, multi-point, dispersed, and evenly fed rice bran, wheat bran, fishmeal composite bait, the feeding amount is 1%-2% of the total weight of thin-shelled snails; if the maximum temperature on the day is between 20-28 °C, at 8 a.m. every day, multi-point, dispersed, and uniform feeding of rice bran, wheat bran, fishmeal compound bait, The amount fed is 2%-3% of the total weight of thin-shelled snails. Because the thin-shelled snail moves slowly and the daily movement distance is short, the feeding bait should be as uniform as possible and leave no blank space. When feeding, it is also necessary to adjust the amount of feeding on the day according to the water quality and lean condition.
(3) Prevention and control of diseases and insect pests.
After the snail seedlings are released, every 25 days, 5-10 kg of pure quicklime per mu is applied to disinfect the field. Grass carp, carp, crucian carp, bluefish, etc. are not polycultured in the field to avoid being swallowed by the field snails. Regularly use grass soaked in pig blood to trap and kill ants; cut the weeds in the field in time to prevent voles from burrowing; patrol the fields during the day and at night, find water ducks, birds, voles and other predators, and promptly drive away and kill them.
Third, single-cropping late rice cultivation
(1) Seed live broadcasting.
Single-cropping late rice varieties were selected from the hybrid late rice Yongyou 7850 with thick stems, strong disease resistance, lodging resistance and good yield. At the beginning of June, the water level was lowered to 0.05m above the surface, and then the field was finely raked to achieve a flattening, and the field surface drop was within 0.05m. At the same time, the seeds are spread in the sun, soaked in the medicament, rinsed with water, and then germinated; 80% of the seeds are evenly broadcast when the chest is broken and white, and 1kg of seeds are used per acre. After sowing, the valley collapses into the mud to prevent uneven seed fall.
(2) Regulate the water level of the field.
At the seedling stage, lower the water level to the surface of the field, keep the field moist, and promote the growth of seedlings. During the tillering period, the plot is irrigated to 0.05m above the field surface, maintaining the shallow water layer of the field surface, sufficient supply of late rice water, and increasing the effective tillering number. In the long panicle stage, the water level is lowered to 0.10m below the field surface, which promotes the increase in the number of roots and deep roots, which is conducive to resistance to lodging, and ensures that the root system can absorb sufficient nutrients during the fruiting period to supply grain filling. During the fruiting period, first fill the field surface with water to keep the field surface moist; then alternate between wet and dry to avoid premature aging; and lower the water level to 0.10m below the field surface 5 days before harvesting for mechanical harvesting.
(3) Topdressing once.
At the end of tillering, 1:1:5 mixed liquid of sheep manure, duck manure and water 1500 kg per mu was applied as topdressing to increase the fertility of the field and promote the root growth, more fruiting and full grain of late rice. In order to ensure the safety of thin shell snails, no chemical fertilizer is applied.
(4) Comprehensive control of diseases and insect pests.
The selection of biological pesticides to control striated blight, rice aspergillosis and other diseases. In summer, the field snail adsorbed around the rice can well prevent rice planthoppers; agricultural methods, physical methods, or spraying high-efficiency and low-toxicity pesticides to control insect pests such as dimorphic borers and longitudinal leaf borers. Spray high-efficiency and low-toxicity pesticides after the dew is dried on sunny days, and properly raise the water level of the field before appropriately, minimize the pesticide into the water, and do not affect the growth of thin-shelled field snails.
(5) Mechanical harvesting.
In late October, the single-season late rice is harvested by the rushing machine. Before harvesting, samples are taken to check the retention of thin-shelled field snails on the field surface to ensure that more than 90% of the thin-shelled field snails are in the ditch before harvesting. Do not cut the green, the particles returned to the warehouse.
Fourth, thin shell field snails are captured
In late September, the faster-growing thin-shelled snails have grown to 15-25g and can be caught and marketed. Every morning, a special net is used to catch in a large ditch, and the large catch is left small, and the thin shelled field snails are packed in bamboo wilts. After collecting all the thin shell snails every day, they are wholesale to the distributors at one time, not temporarily raised, reducing mortality and increasing production. When this method is used to harvest the late rice in late October, 1.0-2.0 kg per mu can be caught per day. After the harvest of the late rice in a single season, the plot is irrigated to 0.05m above the field surface. After that, at noon every day, go to the field to pick up thin shell snails and put them in bamboo wilts. This method is used to catch 1.5-3.0 kg per acre per day until November 20.
In late November, on a sunny afternoon, lower the water level to 0.03m above the ditch. At noon the next day, there are basically no thin shell field snails in the field surface, and there are a small number of thin shell field snails in the small ditch; to the large ditch and small ditch, the snail is picked up at one time, leaving some of the female snails as the next year's seed snails, leaving all the snails as the next year's snail seedlings. After picking, the plot is immediately filled to 0.10m above the field surface to ensure the healthy survival of the thin shell snails left.