How to Achieve High Yield and Efficiency in Rice-Fish Rotation? A Detailed Explanation of the Field-Pond Technique

The field-pond rice-fish rotation is a high-yield, high-efficiency technical model formed in western Fujian over the past two years through continuous improvement based on the extension of "pit-pond" and "ditch-trench" rice-field @#@233@#@. In 2000, Longyan City extended rice-field fish farming over 20,000 mu, of which the field-pond rice-fish rotation area was nearly 5,000 mu. On March 21 this year, the Longyan City Animal Husbandry and Fisheries Bureau and the Liancheng County Science and Technology Bureau organized relevant experts to conduct an on-site sampling inspection of the rice-field fish farming on Li Jincai's household's 1.8 mu of paddy field in Songyang Village, Gechuan Township, where this model was implemented. The total output of fresh fish was 1,112.5 kg, the total fish output value was 8,482.5 yuan, and the total gross profit was 5,248.5 yuan, equivalent to a per-mu fish yield of 618 kg, a per-mu fish output value of 4,712.5 yuan, and an average per-mu gross profit of 2,915.8 yuan. At the same time, rice output increased by about 10% compared with previous years, with wet grain yield reaching 833.5 kg per mu. The high-yield, high-efficiency goal of "a thousand jin of rice and a thousand jin of fish" was achieved. In order to vigorously extend this high-yield, high-efficiency rice-fish farming technique, the Fujian Provincial Ocean and Fisheries Bureau held a provincial on-site meeting on rice-field aquaculture in Liancheng County. The main technical points of this model are briefly introduced as follows:

I. Basic Facilities

1. Raise, widen, and reinforce the field ridges to form a deep-water fish-rearing pond. Methods such as brick masonry, cement plastering, and laying cement precast blocks can be used to permanently reinforce the field ridges. The field ridges are required to be raised to 1.5 m so that the water depth during the fish-rearing period can reach more than 1.2 m. The field ridges should be widened to more than 1 m so that ryegrass, corn grass, Sudan grass, etc. can be planted. It is even better if part of the green fodder land can be provided as supporting infrastructure.

2. Properly arrange the inlet and outlet. Cement pipes or bamboo tubes can be used, with a 60-mesh silk gauze net added at the inlet to intercept harmful organisms, and a 20-mesh bolting silk installed at the outlet to prevent escape. The inlet and outlet should be arranged diagonally as much as possible to form convection, which is conducive to water exchange and maintaining sufficient dissolved oxygen.

3. Equip small ponds for fingerling cultivation at a ratio of 10%. Generally, 0.1 mu of seedling field per mu of paddy field is used. After the early-season seedlings are removed from the field, it is immediately raised and reinforced into a pit pond, and summer fry are promptly stocked for intensive cultivation as reserve fingerlings for rice-field fish farming.

II. Fingerling Stocking

1. Cultivation of reserve fingerlings for rice-field fish farming. For every 0.1 mu, stock 1,350 summer fry of various species, including 500 grass carp, 200 silver carp, 100 bighead carp, 300 Jian carp, 200 Pengze crucian carp, and 50 others. After about 70 days of cultivation, they become autumn fingerlings.

2. Stocking for grow-out fish farming in late-season rice fields. If the planned yield per mu is 500 kg, the stocking rate is required to be 850 fish, including 300 grass carp fingerlings over 20 cm, 150 silver carp fingerlings and 50 bighead carp fingerlings at 25 cm, 200 Jian carp fry at 10 cm, 100 Pengze crucian carp or engineering crucian carp, and 50 other fingerlings.

III. Production Management

1. Preparation Before Stocking Fingerlings in the Paddy Field

1After the early rice is harvested, immediately clear away weeds around the field edges. 2Raise and reinforce the field ridges, and inspect and eliminate hidden leakage hazards. 3Arrange flood drainage and anti-escape facilities at the inlet and outlet. 4Ten days before fingerling stocking, disinfect the paddy field with 75-100 kg of quicklime per mu. 5Seven days before fingerling stocking, apply 300 kg of decomposed manure per mu. 6Fill the field pond with water.

2. Disinfection of Stocked Fingerlings

1Five to seven days before transfer and capture, fingerlings should be splashed throughout the pond with 0.7 ppm copper sulfate or 0.3-0.5 ppm trichlorfon. 2Before being put into the pond, grass carp fingerlings must be injected with the grass carp "four-in-one" vaccine, then soaked in 5 ppm mercurous nitrate for 10 minutes, and then transferred into the pond.

3. Feeding Management

1The "four fixed" feeding method. That is, fixed quality, fixed quantity, fixed location, and fixed time, ensuring the nutritional needs of fish while avoiding waste and water pollution. 2The "four diligent" management method. That is, diligently patrol the pond, diligently observe water color, diligently inspect, and diligently prevent fish diseases. 3Feed and feeding standards. For grass carp as the main species, a combination of formulated pellet feed and high-quality green fodder should be adopted. If self-made formulated pellets are used, they are required to remain stable in water for more than 10 minutes. The formula can be: soybean meal 45%, rapeseed cake 10%, rice bran 13%, wheat bran 12%, wheat middlings 16.5%, vitamin premix 1%, mineral salt premix 0.95%, monocalcium phosphate 0.5%, and per ton of feed add 500 g vitamin C and 3,000 g lysine. The feed conversion ratio of this feed formula is 1.5-1.8.

It is crucial to scientifically determine the daily feeding amount for fish. The feeding rate can be determined according to fish body size and water temperature. Practice has verified that the feeding rates from May to early October are as follows:

Fish size (g) 25 50 75 100 150 200 250 300 400 500 600

Feeding rate (%) 4.5 3.7 3.4 3.2 3.0 2.8 2.5 2.3 2.0 1.7 1.4

In winter, because the weather is cold, the feeding intake of fish decreases significantly, and the feeding rate should be lowered accordingly. In extremely cold weather, it is only 1%, and feeding 3 times a week is sufficient; from December to February of the following year, calculate at 60% of the listed table and feed once a day; from mid-October to November and from March to April of the following year, calculate at 80% of the listed table and feed twice a day. Each month, 30 fish should be randomly selected and weighed to determine the average individual weight, then multiplied by the total number of fish to obtain the total weight of fish in the pond, and the total feeding amount should be calculated according to the feeding rate. The feeding amount is customarily fine-tuned once a week.

IV. Summary and Discussion

1. In the "field-pond" rice-fish rotation, because intensive pond culture techniques are introduced into rice-field fish farming, high yield and high efficiency can be obtained, achieving a double harvest of rice and fish. From the practice in western Fujian, rice-field fish farming has begun to leap from an auxiliary position in field agriculture to a leading position, and the income ratio of fish to rice is generally 5:1. This high-yield rice-fish farming model is a good form for promoting the optimization of field agricultural structure and the sustainable development of fisheries, and it is also a new growth point for rural economic development and a new bright spot for increasing farmers' income.

2. The innovation of the field-pond rice-fish rotation lies in changing traditional flat-panel rice-field fish farming from an extensive style to an intensive style, deepening the water level, increasing the number of stocked species, feeding formulated pellet feed, and improving water quality through aeration. The field ridges have been improved from the original once-a-year repair to permanent engineered pond ridges, the cultivated layer is well protected, and there is no distinction between field and pond, making it suitable for both rice and fish and very convenient to use and extend. Compared with "ditch-trench" and "pit-pond" rice-fish co-culture, it completely overcomes the conflicts with pesticide application, chemical fertilizer application, and field drying. Moreover, it eliminates the heavy labor of digging ditches and pits for rice-field fish farming every year. The rice-fish rotation method creates a mutually beneficial relationship between rice and fish. It has been verified that both fish and rice pests and diseases are reduced, and rice yield is somewhat higher than under single management. This method is suitable for extension in subtropical or central subtropical single-season rice planting areas, and is easy for the public to accept.

3. At present, the varieties used in rice-field fish farming in the mountainous areas of western Fujian are still relatively limited. Exploration should be strengthened in rice-field @#@234@#@, @#@235@#@, frog farming, and other aspects, continuously opening up new fields of rice-field ecological aquaculture, and by drawing on high-quality, high-benefit rice-field aquaculture from provinces such as Jiangsu, Zhejiang, and Anhui, the effectiveness of "field-pond" rice-field aquaculture can be brought to a new level.