Soilless Cultivation Technology: Growing Crops Without Soil
It is generally believed that agricultural production cannot do without soil. However, this situation may change in the future. At the recent National "12th Five-Year Plan" Science and Technology Innovation Achievement Exhibition, an achievement called the "Intelligent LED Plant Factory" received widespread attention. This technology, hailed by the industry as one that overturns "land use and farming methods," what exactly is new about it? And how is this cultivation technology progressing in China?
With the help of plant factories, humans can even carry out crop production in space, deserts, the Gobi and other regions
The Institute of Environment and Sustainable Development in Agriculture of the Chinese Academy of Agricultural Sciences (hereinafter referred to as IEDA of CAAS) is an important base for plant factories in China, and it was precisely this team's independently developed achievement that was unveiled at the National "12th Five-Year Plan" Science and Technology Innovation Achievement Exhibition. Yang Qichang, a researcher at IEDA of CAAS, said that China has now mastered the key technologies of the intelligent LED plant factory, and its overall level is at the international frontier.
The so-called plant factory is a highly efficient agricultural system that achieves year-round continuous crop production through high-precision control within a facility. It uses computers to control environmental factors such as temperature, humidity, light, carbon dioxide concentration and nutrient solution throughout the plant's growth process around the clock, and is a labor-saving production method that is not subject to, or rarely subject to, the constraints of natural conditions.
Yang Qichang explained that agricultural production is the process by which plants produce carbohydrates through photosynthesis. Following this scientific principle, the intelligent LED plant factory, according to the nutrient and sunlight needs of different crops, automatically adjusts the environmental factors and nutrient factors within the "factory" in real time, precisely supplying the plants to ensure their healthy growth. In this way, it achieves all-weather intelligent plant production without soil and without sunlight, and humans can even carry out crop production in non-arable land such as space, deserts and the Gobi.
Unlike traditional agricultural production methods, plant factories have seven major technical advantages: First, crop production is highly planned, and balanced year-round production can be achieved under conditions unaffected by the external environment; second, the yield per unit area is high, which can greatly improve resource use efficiency; third, the degree of mechanization and automation is high, labor intensity is low, and the working environment is comfortable; fourth, no pesticides are applied, and the products are safe and pollution-free; fifth, multi-layer, three-dimensional cultivation saves land and energy; sixth, it is not subject to, or rarely subject to, the influence of geographical, climatic and other natural conditions; seventh, it is closely integrated with modern biotechnology and can produce rare, high-priced, nutrient-rich plant products.
"China has a large population and little arable land, and per capita resources are relatively insufficient. At the same time, people's demand for clean and safe agricultural products is becoming more and more urgent. Under such circumstances, developing plant factories now is very necessary," said Yang Qichang.
The plant factory is currently a hot spot in global agricultural high-tech research. Because it integrates new technologies such as modern biotechnology, intelligent equipment and information technology, it is also an important symbol of a country's high level of agricultural technology.
Yang Qichang believes that in the future plant factories are expected to overturn traditional farming methods, represent the direction of agricultural development, and that mastering the core key technologies of plant factories is of strategic significance.
China began research and development of plant factories in the 1990s, and currently has about 100 artificial-light plant factories
In recent years, plant factories have developed rapidly in East Asia, Europe and America, especially in Japan, South Korea, the United States, Singapore and other countries and regions. International well-known enterprises such as Philips, Panasonic and General Electric have also successively entered the technical research and industrial promotion of plant factories, and the development of plant factories worldwide is extremely active.
Looking back at the development history of plant factories, from the 1940s to the present, it has mainly gone through three stages: early experimental exploration, demonstration application and the current rapid development.
From the 1940s to the early 1970s was the experimental exploration stage. This stage was the period of concept formation and experimental exploration of plant factories, in which breakthroughs in two technologies played an important supporting role in their development. One was "nutrient solution cultivation technology," and the other was "artificial simulation and controlled environment technology," marked by the first artificial climate chamber established by an American scientist in Pasadena, California, in 1949. Afterwards, Japan and the Soviet Union successively built large artificial climate chambers for plant cultivation experiments. During this period, plant factories were small in scale, only from several dozen sq m to several hundred sq m. The scope of application was also relatively narrow, mainly limited to laboratories and demonstration farms. The light source was high-pressure sodium lamps, and the energy consumption of light sources and air conditioning was large, resulting in relatively high operating costs.
From the 1970s to the late 1990s was the demonstration application stage, with breakthroughs in hydroponic cultivation and artificial light source technology as important markers. The emergence of nutrient film technique in 1973 and the subsequent invention of deep flow technique laid the foundation for the development of plant factory cultivation technology. During this period, plant factories in Japan developed rapidly. By the end of the last century, Japan had about 20 artificial-light plant factories. At this stage, artificial light sources continued to improve, high-pressure sodium lamps were gradually replaced by fluorescent lamps, red LED began to be applied, and the energy consumption of light sources was further reduced; sensor and automatic control technology was gradually introduced; and the scope of demonstration application continued to expand.
From the beginning of the 21st century to the present, plant factories have developed rapidly, mainly thanks to the emergence of blue LEDs, the successful development of combined red-blue LED light sources, and the application of network-based intelligent control technology. With the application of LEDs, the energy consumption of artificial light sources in plant factories has been significantly reduced, the spacing between cultivation layers has been further shortened, and the energy efficiency ratio has been greatly improved; at the same time, the application of sensors, intelligent controllers and Internet of Things technology has made intelligent control of plant factories possible.
During this period, various countries accelerated their research and development efforts and industrialization pace for plant factories. In 2009, Japan proposed a plan to vigorously develop plant factories and revitalize modern agriculture. Since 2009 in South Korea, the government has supported scientific research institutions and enterprises to jointly carry out research and development of artificial-light plant factories, and within several years more than 10 models of plant factory products were launched. On the one hand, the United States hopes to provide food security for space stations and planetary exploration through research on plant factories; on the other hand, it has proposed the concept of "skyscraper agriculture," hoping to break through resource bottlenecks spatially, and design models such as the Chicago high-rise farm and the New Jersey "vertical farm" have successively appeared. China began research and development work on plant factories in the 1990s, successfully developed a natural-light plant factory in 2002, developed an LED plant factory experimental system in 2005, and first exhibited a household LED plant factory at the 2010 Shanghai World Expo. In 2013, the state officially included the "Research on Intelligent Plant Factory Production Technology" project in the "863" Program, with 15 scientific and educational institutions and enterprises jointly conducting technological research and development. At present, China has about 100 artificial-light plant factories of different scales.
In 2009, China built its first intelligent plant factory, which has now been promoted to more than 20 provinces
Seeing the hardship of farmers working the land, Yang Qichang often thought as a child: "How great it would be to farm without soil!" In the 1990s, Yang Qichang keenly realized that plant factories were the direction of future development. He led his research team in devoted study, was the first to propose "light formulas" for multiple plants, and created LED energy-saving light sources based on light formulas and their light environment regulation technology and equipment, completing a number of pioneering works in the industry--
For the first time, proposed the "light-temperature coupled energy-saving environment regulation" method and created energy-saving environment regulation technology and equipment for plant factories; was the first to propose the "light-nutrient regulation of vegetable quality" method and created a pre-harvest short-term continuous lighting process and technical equipment for improving quality; was the first to propose intelligent control methods for improving light efficiency, energy efficiency and nutritional quality in plant factories, and created an intelligent control system based on the Internet of Things.
In 2009, the plant factory research and development team of IEDA of CAAS and Beijing Zhonghuan Yida Facility Horticulture Technology Co., Ltd. developed China's first intelligent plant factory. At present, this technological achievement has been promoted to more than 20 provinces, autonomous regions and municipalities including Beijing, Shanghai and Shandong.
China's plant factories are gradually moving onto the international stage. From 2012 to 2015, China held four consecutive international training courses on plant factory technology, and trainees from more than 20 countries received systematic plant factory training. Plant LED light source products based on light formulas have been promoted to the United States, Japan, Europe and elsewhere, and complete plant factory products have been promoted to Singapore and other places.
Although plant factories have many advantages, they also face some "bottlenecks" in the actual development process. Yang Qichang said that the core of the popularization and promotion of plant factories is industrial productization, and from the current point of view, the research and development of standardized and modular equipment for plant factories still needs improvement. In terms of research and development strength, those currently participating in research are mainly scientific research institutions, universities and small and medium-sized enterprises.
"I hope that in the future large Chinese enterprises can actively participate in this. Only by achieving standardized and large-scale production of plant factories can we have a position in international competition," said Yang Qichang. From the perspective of economic benefits, compared with open fields and greenhouses, plant factories, due to reasons such as relatively high initial construction costs and large energy consumption, generally still have relatively high unit production costs, and costs still need to be further reduced in the future.