Earthworms can promote the transformation of Cu, Zn, Cd, Ni and other heavy metals into exchangeable and water-soluble states, but have little effect on the chemical forms of Pb and Cr, and the comprehensive effect of earthworms on the forms of heavy metals has reached a significant level (P = 0.05 1). The results of this study show that earthworm can activate Cu, Zn, Cd, Ni and other heavy metals in sludge, which is consistent with the research results of Sizmur et al., but in this experiment, earthworm has no significant effect on the forms of heavy metals such as Pb and Cr. It shows that the forms of heavy metals Pb and Cr in sludge are relatively stable and difficult to be activated.
Earthworms can have an important influence on many processes that determine soil fertility and are called "ecosystem engineers". Through feeding, digesting, excreting and digging holes, it forms countless reaction circles inside and outside the body, thus affecting the biological, chemical and physical processes of the ecosystem. Earthworm ecosystem is not only a consumer, decomposer, but also a regulator. Its functions in the ecosystem are as follows:
A) Effects on key processes such as organic matter decomposition and nutrient cycling in soil;
B) Effects on soil physical and chemical properties;
C) Interaction with plants, microorganisms and other animals. The activities and functions of earthworms in the ecosystem are comprehensively controlled by maggot ecological groups, population number, vegetation, parent rock, climate, time scale and land use history. The relationship between the invasion of alien species earthworm and ecosystem, and the response and influence of earthworm to global change are two issues worthy of attention. The complexity of soil itself, the lack of knowledge of earthworm natural history and biogeography, and the lag of field control methods of earthworm community all limit the development of earthworm ecology. ?
In recent years, the world trade in earthworm food has gradually increased, with an annual growth rate of 20%. As a kind of food, earthworm is rich in protein, amino acids, fats, minerals, vitamins and trace elements. In some countries, such as the United States and Africa, earthworms are used to make various dishes and canned food. In Taiwan Province Province, China, maggots claim that food is very popular, with about 20-30 kinds of snacks and dishes. Earthworms have been introduced into dining tables in Chengdu, Sichuan and other regions of China, and used to make various seasoning packages and so on. But there are also some problems.
For example, there are some heavy metals and drug residues in earthworm, and people begin to be confused and uneasy about earthworm food, which hinders the development of earthworm in food. However, with the continuous improvement of people's living standards, their own health has become the most important part of life. Earthworms are rich in protein, which is higher than some meat and eggs. In the future, insect food will become the main source of protein. Therefore, earthworm food is the main trend of future development.
Earthworm manure is mainly used for biological fertilizer, soil improvement, detoxification, adsorbent, pest control and so on. Different from ordinary fertilizer, it is odorless, tasteless, granular and has good water absorption and permeability. Studies have shown that it contains more minerals than cow dung. It is reported that adding about 40% earthworm manure to replace the complete feed during the feeding restriction period of laying hens has played a good role. Adding a certain amount of earthworm manure to broiler diet can reduce the occurrence of NH3 and ascites in chicken coop, increase weight gain, reduce feeding cost and improve broiler breeding efficiency.
On the one hand, the application of earthworm manure in soil can adjust the physical properties of soil, which is beneficial to the growth of plants, on the other hand, it can obviously increase the nutrient content of soil and enhance the fertility of soil. Earthworms excrete feces after eating livestock manure, which can not only be used as good feed and fertilizer, but also be a good deodorant for livestock and poultry. In a steel company in Japan, earthworm dung is used to purify sewage and deodorize. Adding some maggots called manure into chicken coops can reduce H2S and NH3 in chicken manure and achieve a certain deodorization purpose. Adding some earthworm manure to the soil can effectively prevent diseases and insect pests and reduce the incidence of plants.
Earthworms, commonly known as earthworms and eels, are representative animals of Oligochaeta in annelids. Earthworms are saprophytic living animals, living in humid environment and feeding on decaying organic matter. The living environment is full of microorganisms but seldom gets sick, which is related to the unique antibacterial immune system in earthworm.
Scientifically, they belong to one-way earthworm order. The body is cylindrical (different from linear animals), with symmetrical sides and segmented phenomenon: it consists of more than 100 sections, and after the eleventh section, there is a back hole in the center of each section; It has no bones, belongs to invertebrates, and its body surface is bare without cuticle. Except for the first two sections of the body, all other sections have bristles. Hermaphroditism, allofertilization, spawning and cocooning through the girdle during reproduction, and breeding the next generation. At present, there are more than 2500 kinds of earthworms. Darwin pointed out in 188 1 that earthworm is the most important animal group in the evolutionary history of the world.
References:
Baidu encyclopedia earthworm