Modern hydroponics has gained wide popularity in recent years. At the end of last year, the Hong Kong Government released a consultation paper on agricultural policy, indicating that hydroponics is a highly efficient and clean technology that can be further developed. Hydroponics can be carried out in an enclosed area or even vertically to save space, so several hydroponic plants have begun operating in industrial buildings in Hong Kong. Agricultural produce from hydroponics is free from bacteria, safe and healthy to eat. Hydroponics is viewed by many as the future of local agriculture, to replace traditional farming.
The major difference of hydroponics with traditional farming is the absence of soil. In traditional farming, crops are planted in soil from which water, minerals and other trace elements are absorbed. In hydroponics, which uses no soil, minerals are dissolved in water to provide nutrients directly to the crops. Sometimes materials such as wood shavings, coconut fibres, polystyrene and mineral wool are needed to provide support for the roots. However, not all crop plants can fit in hydroponic systems, though they can produce quite a number of fruits and vegetables, such as salad vegetables, tomatoes, cucumbers, sweet peppers, strawberries, beans, carrots and potatoes.
In Hong Kong, hydroponics has become popular in recent years. A growing number of hydroponic vegetable farms have appeared in industrial buildings, on rooftops and even outdoors on farmland. In 2013, the Vegetable Marketing Organisation established the Controlled Environment Hydroponic Research and Development Centre to develop its own brand of hydroponic vegetables, to demonstrate controlled environment hydroponic technologies. At the end of last year, the government released a public consultation document entitled "The New Agricultural Policy: Sustainable Agricultural Development in Hong Kong", and recommended the introduction of modern agricultural production methods. The document described hydroponics technology as efficient and clean, able to transform vacant industrial buildings into plant factories.
Relying on energy for production
There are a number of advantages to hydroponics. Firstly, the fact that soil is not needed eliminates the problem of soil erosion and degradation. Secondly, as a highly controlled farming method, crops are grown in an enclosed and clean environment, free from pests, and so pesticides are not necessary. Nor are fertilisers required, as minerals needed by the plants are artificially controlled, avoiding the risk of pollution from chemical fertilisers and bacterial pollution from animal manure. Aseptic production is attainable with hydroponic farming, since high concentrations of minerals are used and traditional organic materials are not used.
In addition, hydroponics employs technology to adjust lighting, temperature, and mineral concentrations to shorten production times, as well as utilising vertical spacing for multiple levels of planting. In an area of the same size, hydroponics can produce several times more crops than traditional farming, which greatly increases the efficiency of land use.
Yet, there is much concern regarding whether hydroponics is truly environmentally friendly. Traditional farming methods are based on various processes, reactions, material cycles and biodiversity in nature. Under suitable weather conditions, crops take up energy from the Sun and absorb minerals released from organic matter decomposed by microorganisms. In organic farming, no chemical fertilisers and pesticides are used during the entire planting process. Hydroponic farming, by contrast, is closed off from the natural environment and involves an artificial process. All the growth conditions, including lighting and nutrients, are maintained through energy consumption.
In the most ideal case, the lighting for hydroponics could be maintained by renewable energy. But if it runs on fossil fuels, there would be a lot of pollution and greenhouse gases produced. In addition, the minerals used in hydroponics are industrially produced at high concentrations that can be diluted. The production process of these minerals includes mining, chemical synthesis, and transportation. Each step of the process contributes to various degrees of environmental problems. If taking into account the life cycle of the entire ecosystem and the issue of energy consumption, it is questionable whether hydroponics really is an environmentally friendly mode of farming.
Do not overlook ecological value of agricultural land
There have been attempts to apply organic agricultural concepts in hydroponics, such as using natural extraction of nutrients instead of industrially produced minerals. Nonetheless, many European countries, Canada, Mexico, New Zealand, Japan and even Hong Kong prohibit the labelling of hydroponic crops as organic produce. However, much controversy has been stirred up among the US organic certification agencies. The National Organic Standards Board, which is responsible for making recommendations for organic standards, firmly rejected the eligibility of hydroponic produce for organic certification, based on the board’s definition set in 1995 that an organic farming system “promotes and enhances soil biological activity”. On the other hand, the USDA’s National Organic Programme, which is responsible for the implementation of organic certification, approved of organic certification for hydroponic produce. The approval was given on the basis that the farming method can foster cycling of resources, promote ecological balance, and conserve biological diversity, without the requirement of planting in soil. In view of the high degree of interest from consumers and comparatively higher pricing for organic foods, the hydroponic sector does fight for organic certification. Consensus has yet to be made on the role of soil.
The local organic foods sector and conservation groups also have doubts regarding hydroponics. To begin with, hydroponics is operated in a highly controlled artificial enclosed system, mostly in indoor or semi-outdoor facilities. Whether it can be classified as farming activity is questionable. Secondly, traditional farming has an irreplaceable role in the ecosystem and is an example of coexistence of human activity and nature. Hong Kong’s Long Valley, for instance, is a famous area of farmland where 200 species of birds have been recorded, including species vulnerable to global extinction. Various species of dragonflies, butterflies and birds are also commonly found in typical agricultural lands in Hong Kong. Agricultural lands are green open spaces filled with various plants. While preserving green space in the countryside, they can help reduce the urban heating island effect. Therefore, preserving agricultural lands has ecological significance, especially high-quality and organic farming agricultural lands that are more sustainable than hydroponics.
On the other hand, agricultural lands are destroyed if they are covered with cement to develop hydroponics. It is even more worrisome in the event that people use hydroponics to disguise their development plans. In the vicinity of Shui Mei Village of Kam Tin, large plots of agricultural land have been filled in with rubble—reaching two metres in height—in recent years. The person-in-charge claimed that the layering of land was for agricultural purposes, and a signboard referring to hydroponics was erected at the location. The question must be asked whether such practice is indeed a smokescreen for the concreting of agricultural lands in the name of hydroponic development. The government must restrict the development of hydroponics on non-agricultural lands, to prevent damage to existing farmland.
Hydroponics can play a role in increasing local food supplies by producing vegetables. Currently, it is seen as a food production industry. In the long term, environmentally friendly hydroponic systems such as aquaponics should be developed. In terms of government policy, whether industrial building contracts should allow hydroponics is still unclear. The government must coordinate in various ways, for more strategic development of hydroponics alongside traditional farming, to allow local agriculture to thrive.
Text | Henry Lui & Dr. Cheng Luk-ki