Can you "farm" without soil?

It is generally believed that agricultural production is inseparable from soil. However, that may change in the future. At the National "12th five-year Plan" Science and Technology Innovation Achievement Exhibition held not long ago, an achievement called "Intelligent LED Plant Factory" attracted wide attention. What is new about this technology, which is praised by the industry as subverting "land use and farming methods"? What is the progress of this cultivation technology in our country?

With the help of plant factories, human beings can even produce crops in space, deserts, Gobi and other areas.

The Institute of Agricultural Environment and Sustainable Development of the Chinese Academy of Agricultural Sciences (hereinafter referred to as the Institute of Environmental Development of the Chinese Academy of Agricultural Sciences) is an important position of plant factories in China. It is the independent research and development achievements of the team that appeared in the national "12th five-year Plan" scientific and technological innovation achievement exhibition. Yang Qichang, a researcher at the Institute of Environmental Development of the Chinese Academy of Agricultural Sciences, said that at present, China has mastered the key technologies of intelligent LED plant factories, and the overall level is at the forefront of the world.

The so-called plant factory is an efficient agricultural system that realizes the annual continuous production of crops through high-precision control in the facilities. it is a labor-saving mode of production in which the temperature, humidity, light, carbon dioxide concentration, nutrient solution and other environmental elements of the plant growth process are controlled all-weather and are not or rarely restricted by natural conditions.

Yang Qichang explained that agricultural production is the process by which plants produce carbohydrates through photosynthesis. Following the scientific principle, the intelligent LED plant factory, according to the demand for nutrition and sunlight of different crops, automatically allocates the environmental and nutritional elements in the "factory" in real time and accurately supplies plants to ensure the healthy growth of plants, so as to achieve all-weather intelligent plant production, and human beings can even carry out crop production in space, desert, Gobi and other non-arable land.

Different from the traditional agricultural production mode, plant factories have seven technical advantages: first, crop production planning is strong, and annual balanced production can be achieved without the influence of external environment; second, high yield per unit area can greatly improve the efficiency of resource utilization; third, mechanization, automation, low labor intensity and comfortable working environment; fourth, no application of pesticides, product safety and no pollution. Fifth, multi-layer, three-dimensional cultivation, saving land and energy; sixth, not or rarely affected by geography, climate and other natural conditions; seventh, closely combined with modern biotechnology, can produce rare, high-priced, nutrient-rich plant products.

"China has a large population, little arable land, and relatively insufficient per capita resources. At the same time, the demand for clean and safe agricultural products is becoming more and more urgent. Under this situation, it is very necessary to develop plant factories. " Yang Qichang said.

At present, plant factory is the focus of global agricultural high-tech research, because it integrates new technologies such as modern biotechnology, intelligent equipment and information technology, and it is also an important symbol of a country's high-tech level of agriculture.

Yang Qichang believes that plant factories are expected to subvert traditional farming methods in the future, representing the direction of agricultural development, and mastering the core key technologies of plant factories is of strategic significance.

China began its research and development of plant factories in the 1990s, and now has about 100 artificial light plant factories.

In recent years, plant factories have developed rapidly in East Asia, Europe and the United States, especially in Japan, South Korea, the United States, Singapore and other countries and regions. Philips, Panasonic, General Motors and other international well-known enterprises have also intervened in the technological research and development and industrial promotion of plant factories, and the development of global plant factories is very active.

Reviewing the development process of plant factory, from the 1940s to the present, it has mainly gone through three stages: early experimental exploration, demonstration application and current rapid development.

The period from the 1940s to the early 1970s was the stage of experimental exploration. This stage is the period of conceptual shaping and experimental exploration of plant factories, in which two technological breakthroughs have played an important supporting role in its development, one is "nutrient solution cultivation technology" and the other is "artificial simulation and control environment technology". It is marked by the first artificial climate chamber established by American scientists in Pasadena, California in 1949. Since then, large-scale artificial climate rooms have been built in Japan and the Soviet Union to carry out plant cultivation experiments. During this period, the plant factory was relatively small, ranging from tens of square meters to hundreds of square meters. The scope of application is also relatively narrow, mainly limited to laboratories and demonstration farms. The light source is high pressure sodium lamp, the energy consumption of light source and air conditioning is high, and the operation cost is high.

The demonstration and application stage was from 1970s to the end of 1990s, in which the breakthrough of hydroponic cultivation and artificial light source technology was an important symbol. The emergence of nutrient liquid film technology in 1973 and the subsequent invention of deep liquid flow cultivation technology laid the foundation for the development of plant factory cultivation technology. During this period, Japanese plant factories developed rapidly. By the end of the last century, Japan had about 20 artificial light plant factories. At this stage, artificial light source continues to improve, high pressure sodium lamp is gradually replaced by fluorescent lamp, red LED begins to be used, the energy consumption of light source is further reduced; sensor and automatic control technology are gradually introduced; demonstration application is expanding.

The rapid development of plant factories since the beginning of the 21st century is mainly due to the emergence of blue LED and the successful development of red and blue LED combined light source, as well as the application of intelligent control technology based on network. With the application of LED, the energy consumption of artificial light source in plant factory is significantly reduced, the distance between cultivation layers is further shortened, and the energy efficiency ratio is greatly improved; at the same time, the application of sensor, intelligent controller and Internet of things technology provides the possibility for intelligent management and control of plant factory.

During this period, countries accelerated the research and development of plant factories and the pace of industrialization. In 2009, Japan put forward plans to vigorously develop plant factories and revitalize modern agriculture. Since 2009, the government has supported scientific research institutions and enterprises to jointly carry out the research and development of artificial light plant factories, and more than 10 models of plant products have been launched within a few years. On the one hand, the United States hopes to provide food security for space stations and planetary exploration through the study of plant factories, and on the other hand, it has put forward the idea of "skyscraper agriculture", hoping to break through the bottleneck of resources in space. design patterns such as Chicago Tower Farm and New Jersey "Vertical Farm" have emerged successively. China began the research and development of plant factories in the 1990s, successfully developed natural light plant factories in 2002, developed the experimental system of LED plant factories in 2005, and exhibited family LED plant factories for the first time in the 2010 Shanghai World Expo. In 2013, the country formally included the project of "production technology research of intelligent plant factory" in the "863" plan, and 15 scientific and educational units and enterprises jointly carried out technology research and development. At present, there are about 100 artificial light plant factories of different sizes in China.

In 2009, the first intelligent plant factory was built in China, which has been extended to more than 20 provinces.

Seeing the hardships of farmers in farming, Yang Qichang often thought when he was a child: "farming without soil" would be nice! In the 1990s, Yang Qichang was acutely aware that plant factories were the direction of future development. He led the research team to put forward the "light formula" of many plants, and created the LED energy-saving light source and its light environment control technology and equipment based on the light formula, and completed a number of innovative work in the industry.

The method of "light-temperature coupling energy-saving environmental control" was put forward for the first time to create energy-saving environmental control technology and equipment in plant factories, and the method of "light-nutrition regulation and control of vegetable quality" was first put forward. create short-term pre-harvest continuous illumination to improve quality technology and technical equipment; take the lead in putting forward intelligent management and control methods to improve light efficiency, energy efficiency and nutrition quality in plant factories, and create an intelligent management and control system based on the Internet of things.

In 2009, the R & D team of the plant factory of Huanfa Institute of Chinese Academy of Agricultural Sciences and Beijing Yida facilities Horticulture Technology Co., Ltd. developed the first intelligent plant factory in China. At present, the technical achievements have been extended to more than 20 provinces, autonomous regions and cities, including Beijing, Shanghai, Shandong and so on.

China's plant factories are gradually moving towards the international stage. From 2012 to 2015, China held four international training courses on plant factory technology, and students from more than 20 countries received systematic plant factory training. Plant LED light source products based on light formula have been promoted to the United States, Japan, Europe and so on, and complete sets of plant products have been promoted to Singapore and so on.

Although the plant factory has many advantages, it also faces some "bottlenecks" in the actual development process. Yang Qichang said that the core of the popularization and promotion of plant factories is industrial production.At present, the research and development of standardization and modular equipment of plant factories still need to be improved. From the perspective of R & D strength, scientific research institutions, universities and small and medium-sized enterprises are mainly involved in the research.

"it is hoped that large Chinese enterprises will actively participate in it in the future. Only by realizing the standardization and large-scale production of plant factories can they have a position in the international competition." Yang Qichang said. In terms of economic benefits, compared with open fields and greenhouses, due to the higher initial construction cost and higher energy consumption, the unit production cost is still relatively high, which still needs to be further reduced in the future.