Can edible mushroom cultivation also drive sustainable agricultural development?

Edible mushrooms are macrofungi with large fruiting bodies that can be eaten, commonly known as mushrooms. Developing the edible mushroom cultivation industry today can not only generate income, but also turn waste into resources and promote the development of organic agriculture. Common edible mushrooms include: shiitake (Lentinula edodes), straw mushroom (Volvariella volvacea), button mushroom (Agaricus bisporus), wood ear (Auricularia auricula-judae), silver ear (Tremella fuciformis), lion's mane (Hericium erinaceus), bamboo fungus (Phallus indusiatus), matsutake (Tricholoma matsutake), Tricholoma mongolicum, russula (Russula spp.), reishi (Ganoderma lucidum), cordyceps (Ophiocordyceps sinensis), truffle (Tuber spp.), white beech mushroom (Pleurotus nebrodensis) and porcini (Boletus edulis), etc.; a few belong to the subphylum Ascomycotina, including: morel (Morchella spp.), saddle fungus (Helvella spp.) and truffle (Tuber spp.), etc. The above fungi grow in different regions and different ecological environments. More than 350 species of edible mushrooms are known in China, most of which belong to the subphylum Basidiomycotina.

Chen Wenxin, an academician of the Chinese Academy of Sciences, recently found through research that the increase in chemical nitrogen fertilizer use is an important reason for the steady rise in ammonia concentration in China's air, especially in the North China Plain where smog is most severe. To change the status quo as soon as possible, he has the following suggestions:

First, convert wastes left by animals and plants into farmyard fertilizer through methods such as cultivating edible mushrooms, turning spent mushroom substrate plus an appropriate amount of chemical fertilizer into fertilizer for farmland;

Second, give full play to biological nitrogen fixation. Through these two measures, the amount of chemical nitrogen fertilizer can be greatly reduced, which can both fertilize the soil and achieve superior high yields of crops, promoting the sustainable development of farming, animal husbandry and fisheries and a better environment.

China's edible mushroom industry has a long history, and the country has excellent conditions for vigorously developing the edible mushroom industry. While producing edible mushrooms, a large amount of spent mushroom substrate is generated. Its crude protein content is higher than 10%, and its fertilizer indicators reach or exceed the content of human feces and urine, pig manure and cow dung, making it a high-quality organic fertilizer. Applying this organic fertilizer will reduce the nitrate and nitrite content in crops, and consumers can get safer agricultural products. Edible mushrooms are an industry that kills three birds with one stone: it harvests the edible mushroom products themselves; it reduces environmental pollution from animal and plant waste; and it produces large amounts of high-quality organic fertilizer. Therefore, developing the edible mushroom industry can not only generate income, but also turn waste into resources and promote the development of organic agriculture.

Global biological nitrogen fixation is about 200 million tons of pure nitrogen each year, equivalent to the total amount of global industrial nitrogen fertilizer today, of which nitrogen fixed by rhizobia symbiotic with legumes accounts for 60%-70%. The nitrogen fixed by this symbiotic system not only meets the needs of its host, but can also be partly supplied to nearby crops for use; while the roots of leguminous plants contain about 35% of their total nitrogen, which can be used by subsequent crops.

In addition, recent research has found that grasses help legumes eliminate nitrogen inhibition, and their secretions can prompt legumes to form nodules, achieving mutual benefit and high yields for both. Therefore, intercropping and rotation of legumes with other plants can reduce chemical fertilizer application while achieving high quality and high yields. The Rhizobium Research Center of China Agricultural University has carried out a series of rhizobia matching screening and field inoculation experiments, all proving that inoculating matched efficient rhizobia can not only replace chemical nitrogen fertilizer, but also improve the yield and quality of leguminous crops.

In the rice fields and winter fallow land of southern China, green manure crops such as Chinese milk vetch (Astragalus sinicus), hairy vetch and sesbania can be planted, or economic legumes such as peas and broad beans can be planted; in northern dry fields, orchards, grasslands and other areas, various leguminous crops or leguminous forages can be widely planted. In short, according to actual conditions, inoculating rhizobia matched with legume varieties and adapted to the planting soil, and widely carrying out intercropping and rotation of legumes with other crops, can greatly reduce chemical nitrogen fertilizer and achieve the sustainable development of China's ecological agriculture.

Edible mushrooms are an emerging strategic industry in China. After 40 years of development, they have become China's fifth largest planting industry after vegetables, grain, fruit and oil. China is the country with the longest history of artificial cultivation of edible mushrooms and the most cultivated species in the world. At present, 60-70 species are cultivated, with 20-30 bulk and common species. Edible mushroom production is found across the north and south of the country, in cities and villages. Edible mushrooms in all their varied forms, as healthy food, have become delicious dishes on the public dining table, and the edible mushroom industry has become a good way to increase agricultural efficiency and farmers' income.

Although edible mushrooms are an important component of the planting industry, and most are eaten as vegetables, their production process and technology are completely different from those of vegetables. All kinds of green crops build themselves through photosynthesis and produce the food humans need. Edible mushrooms are completely different: they use substrate as their nutrient source and rely entirely on their own enzyme systems to decompose and absorb lignin and cellulose, etc., in the substrate, building themselves and ultimately forming fruiting bodies (mushrooms, wood ears). The substrate is equivalent to the soil of green crops and is the entire source of nutrition for edible mushrooms.

Straw from all kinds of crops is a nutrient source for edible mushroom production. As raw material, it becomes edible mushroom cultivation substrate after scientific formulation. China produces 700 million tons of various crop straws and husks annually, and edible mushrooms are precisely a type of organism that efficiently converts straw into economic use. Edible mushroom production is a type of high-tech industry. It can use non-cultivated land such as mountainous land, sloping land, sandy land, wasteland and saline-alkali land for three-dimensional, efficient production, and can be produced with low investment and quick returns in horticultural facilities, producing at least two seasons per year. Each mu of greenhouse can consume 20-30 tons of straw and produce 15-35 tons of mushrooms, equivalent to 0.6-1.4 tons of beef, with protein production efficiency equivalent to 4.8-11.2 times that of beef cattle. Edible mushrooms are characterized by high protein, low fat, low calories, high vitamins and minerals, high dietary fiber and many health-active substances; their entire production process uses sterile operation, clean production and controllable environment. They are increasingly favored by consumers, have become the first choice of healthy food for the public, and have become an important part of China's great health industry.

After various kinds of straw are decomposed by edible mushrooms and produce considerable delicious, nutritious and healthy high-quality food——mushrooms and wood ears, they can also be processed into high-quality animal feed, soilless cultivation substrate, organic fertilizer, etc. After a series of recycling uses, they are finally returned to the field as plant nutrients, cycling infinitely in this way, playing an irreplaceable role in the balance between human social development and the environmental ecology.

In China, edible mushrooms such as oyster mushroom (Pleurotus ostreatus), enoki mushroom (Flammulina velutipes), button mushroom (Agaricus bisporus) and straw mushroom (Volvariella volvacea), which use straw as the main substrate material, have an annual output of about 20 million tons, consuming 24-26 million tons of straw, using only 3.4-3.7% of existing crop straw resources. Influenced by production habits, traditional cultivated species such as wood ear and shiitake among bulk products are still mainly produced with sawdust as the main raw material. With the continuous strengthening of environmental awareness, forestry resources urgently need protection. With the continuous expansion of the edible mushroom industry, sawdust resources are becoming increasingly scarce. In response to this problem, since the beginning of the construction of the National Edible Mushroom Industry Technology System, it has firmly grasped the research and experimental demonstration of new substrate industrialization technology for edible mushrooms based mainly on straw utilization. It has successively carried out research on cultivating edible mushrooms, especially wood ear, oyster mushroom and enoki mushroom, with corncob, corn stalk, rice straw, soybean stalk, cotton stalk and spent mushroom substrate, etc., achieving gratifying results and forming a series of industrialization technologies. At present, corncob, corn stalk, rice straw, soybean stalk, cotton stalk and spent mushroom substrate, etc., can replace 30-70% of traditional main materials such as cottonseed hulls and sawdust, and have been applied respectively in the production of oyster mushroom, wood ear, king oyster mushroom (Pleurotus eryngii) and white beech mushroom, saving costs and increasing efficiency by an average of more than 7%. On the other hand, spent mushroom substrate with straw as the main material is more conducive to digestion and absorption by livestock and poultry, is favored by the feed industry, and can be fully reused to produce feed, saving breeding costs and improving benefits while returning to the field through the animal's belly, with higher fertilizer efficiency. At present, the technology of using straw to replace sawdust and cottonseed hulls in edible mushroom production has been promoted on a large scale in Heilongjiang, Jilin, Hebei, Henan and other places.

China is the first country to use crop straw to cultivate wood-rotting edible mushrooms. In the 1970s, Mr. Liu Chunye invented the cultivation of oyster mushroom with cottonseed hulls, opening the door to straw utilization for the production of many kinds of edible mushrooms. Since then, corncob, soybean stalk, bagasse and rice straw have been applied on a large scale in the production of oyster mushroom, enoki mushroom, king oyster mushroom and others. In recent years, complete sets of edible mushroom cultivation technology using cotton stalk, spent mushroom substrate, mulberry branches, fruit tree branches and hemp stalks, etc., have been developed, expanding the raw material resources for edible mushroom production. Industrial practice has proven that using straw to produce edible mushrooms is economical, safe, efficient, green, environmentally friendly and recyclable, and is an ecological and healthy industry that benefits the country and the people. Edible mushrooms transform straw, which humans cannot eat directly as food, into delicious, nutritious and healthy food. Let us care for, cultivate and enjoy them with our hearts, and let edible mushrooms benefit humanity, the environment and health.