Many years of production practice has proved that raising crabs in rice fields is a new comprehensive tumor model that organically combines planting and breeding. Carry forward the advantages of lake crab and pond crabs, and overcome the shortcomings of these two breeding methods, showing strong vitality and broad application prospects. (1) The eating behavior of crabs eliminated weeds in rice fields, reduced the weeding process in rice planting and reduced the labor intensity of farmers. Weeds in rice fields are usually natural bait that river crabs like to eat, such as Azolla, Ceratophyllum, Sophora alopecuroides and so on. In rice planting, clearing these weeds is a troublesome production process. In the 1970s, China's agricultural sector introduced chemical herbicides from abroad to replace manual weeding, but any herbicide would bring certain pollution to rice and the environment. Raising crabs in rice fields can not only reduce the labor of manual weeding, but also have the repeatability and thoroughness of weeding that chemical herbicides can't match, which can save industry and reduce environmental pollution.

(2) The eating behavior of crabs can eliminate pests in rice fields, reduce the cost of pest control in rice planting and reduce the labor intensity of farmers spraying pesticides. The main pests of rice are mites, dust, leafhoppers, leafhoppers and Mi Chong. These pests are crabs' favorite objects. Crabs can also eat chironomid larvae, dragonfly larvae, mite larvae, red capsules and so on in rice fields. Experiments show that crabs can also remove pests on rice stems, leaves and ears. This biological control function of crabs not only effectively reduces the harm of pests to rice and the pollution of pesticides to the environment, but also greatly improves the ecological environment in rice fields and rural areas. (3) The eating behavior and crawling movement of crabs make the paddy soil loose and reduce the labor force for farmland cultivation. Aquatic organisms in rice fields generally live in shallow mud or soil surface. For example, there are three main types of algae: benthic, semi-benthic and plankton.

River birds are generally earth clocks born in rice fields, forming the bird layer of ornamental communities, mainly composed of diatoms, green algae and cyanobacteria. Semi-oligotrophic algae are mainly filamentous multicellular green algae, whose filaments float in water, but their components adhere to the surface of farmland or extend into mud. Benthic animals such as snails and corals usually live on the muddy surface of fields. Crabs ingest this aquatic organism, which objectively achieves the effect of making farmland soft and breathable, which is conducive to fertilizer decomposition and soil permeability, promoting the development of rice grains and roots, and reducing the hard work of farmers for loosening soil. (4) The crab's life activities play a role in fertilizing rice growth and reducing farmers' agricultural expenditure. Crabs will eat aquatic plants such as algae and weeds in rice fields in their life activities, and the growth of these aquatic plants will consume fertilizers and nutrients in rice fields to varying degrees, which objectively plays a role in supplementing fertilizers for rice growth.

The excrement of crabs is rich in trace elements such as nitrogen, phosphorus and calcium, which are all high-quality fertilizers needed for rice growth and objectively play a role in fertilizing rice growth. The increase of this guarantee has greatly reduced farmers' chemical fertilizer input. Crabs bring so many benefits to the growth of rice, so is rice field suitable for farming? The answer is yes. 1. Paddy fields can provide a good ecological environment for the growth of crabs. Paddy fields usually have soft soil, sufficient dissolved oxygen, suitable water temperature and rich nutrition. Soft soil provides convenience for crabs' life activities, and this kind of soil also provides favorable conditions for the growth of bait organisms. Sufficient dissolved oxygen (from the atmosphere, the water in the rice field is shallow, so the oxygen in the air can be easily dissolved in the rice field), irrigation water, various aquatic plants that carry out photosynthesis in the rice field, and rich nutrients are all necessary conditions for the growth and peeling of crabs. 2. Paddy fields can provide abundant food organisms for the growth and development of crabs.

The composition of aquatic organisms in paddy fields is different from that in ponds. Plankton is more abundant than ponds, and filamentous algae and aquatic vascular plants are much more abundant than ponds. Due to the shallow water environment of paddy field, the water temperature is suitable and the light is sufficient, which provides a good living environment for the growth and reproduction of aquatic plants and benthos. Abiotic factors such as water, soil, light, heat and air are interrelated, interdependent and constrained with plants, animals and microorganisms, forming a whole with unified functions, which provides rich animal and plant food for the growth and development of crabs. According to the analysis, there are 66 species of protozoa in 23 families, 36 species of rotifers in 8 families, 5 species of copepods in 4 families, 209 species of birds in 23 families, 465,438+409 species and subspecies of aquatic plants, and a large number of writing animals. Crabs are raised in rice fields, and rice crabs are born. Through the organic combination of breeding famous products and rice planting, the single planting structure of rice field has been changed, with one water, two water, two water, one water, one water and one water.