Soilless farming/ Hydroponic crop cultivation
G L BANSAL*
What is soilless/dirt free farming?
Traditional agriculture is cultivation of crops/plants in soil. The plants, in fact, do not need soil to grow but for its nutrients. If the plants are grown in nutrient solutions or any other substrate (other than soil) containing essential nutrients, the practice is known as soilless gardening/ dirt free farming.
In a traditional soil-based garden, a plant wastes most of its energy developing a huge root system for it has to search far and wide in the soil for its food and water. In soilless gardening, these are directly available to the plant roots. The plant gets everything it needs, in all the right proportions, at just the right time and utilising it most efficiently. Here the plant shows its full genetic potential. They just bypass the soil and the plant’s requirements are met by nutrient rich water. It is known as Hydroponic cultivation.
The word hydroponics comes from two Greek words ‘hydro’ meaning water and ‘ponos’ meaning labor. This word was first used in 1929 by Dr Gericke, a California professor who began to develop what previously had been a laboratory technique into a commercial means of growing plants. The U.S. Army used hydroponic culture to grow fresh food for troops stationed on infertile Pacific islands during World War II. By the 1950s, there were viable commercial farms in America, Europe, Africa and Asia.
Hydroponics is a system of agriculture that utilizes nutrient-laden water rather than soil for plant nourishment. Such a technology, in fact, has been in operation since 2004 at the South Pole Food Growth Chamber. Hydroponics was indeed chosen as the food-production technology at the South Pole, due to the terms of the 1978 Antarctic Conservation Act which prohibits the ingress of soils to the continent’.
In space also, hydroponic vegetable cultivation is being used that would not only supplement a healthy diet, but also remove toxic carbon dioxide from the air inside their spacecraft and create life-sustaining oxygen. “If you continually resupply and deliver commodities like food, that will become much more costly than producing your own food,” says Ray Wheeler, Plant Physiologist at Kennedy Space Center’s Space Life Sciences Lab.
The popularity of hydroponics has increased dramatically in a short period of time leading to an increase in experimentation and research in the area of indoor and outdoor hydroponic farming.
Categories of soilless farming
Soilless crop cultivation can be categorised broadly into three categories
- Substrate based farming with nutrient solutions using cocopeat, vermiculite, perlite, gravel, sand, haydite, clay pebbles, vydron, rockwool etc
- True hydroponics
- (i) Nutrient Film Technique
- (ii) Deep Water culture
Essential of soilless farming
Apart from light, for soilless farming, plant needs the water based nutrients consisting of five macro elements ( nitrogen, phosphorus, calcium, potassium and magnesium) required in large quantity and seven micro elements ( iron, manganese, copper, sulphur, molybdenum, zinc and borate) needed in small quantity. The ideal EC range is 1.5 and 2.5 ds/m; pH 6.0-6.5
Crops grown in soilless farming
Although any crop can be grown without soil, the most extensively grown leafy crop is lettuce and fruit crops are tomato and strawberry followed by bell pepper and cucumbers. Marijuana is grown in many parts of the world legally and underhand. Many other crops are also being tried in soilless farming with ample dividends. Basically, everything grown in horticulture can be grown in hydroponics. At many places, fodder is also being grown hydroponically.
Why soilless farming?
As the population of our planet soars at an alarming rate and arable land available for crop production declines incessantly, soilless cultivation/ hydroponics offer us a lifeline of sorts and allow us to produce crops in greenhouses or in multilevel buildings dedicated to agriculture. Apart from land, other resources like water and labour are becoming scarce.
In India alone, according to latest data from Ministry of Agriculture, as cited by TOI dated Aug 17, 2013, as many as 20 states reported decrease in cultivable land to the extent of 7,90,000 hectares in four years from 2007-08 to 2010-11. The decrease is mainly attributed to diversion of cultivable land for non-agricultural purposes, including construction, industries and other developmental activities. Likewise earlier, MoEF has revealed on June 10, 2013 that India’s forest cover is depleting at a startling rate of 135 hectares (333acres) per day. Such diversions are done for various projects to include coal mines, thermal power plants, and industrial and river valley projects.
We are not producing enough food and much of what we are producing is unevenly distributed. According to the Food and Agriculture Organisation (FAO) recent estimates, 30 million people a year are dying of hunger (the equivalent of 100,000 folks per day), with another two billion suffering from malnutrition. All over the world there is a growing need for nutritious food rather than mere filling the stomach. Malnutrition is an increasing problem in both developed and developing countries. Currently soaring food prices are buffeted by droughts, floods and the cost of energy required planting, fertilizing, harvesting and transporting it. And prices will only get more unstable. Climate change makes long-term crop planning uncertain.
An estimated 109 hectares of new land (about 20% more land that is represented by the country of Brazil) will be needed to grow enough food to feed the growing population, if traditional farming practices continue as they are practiced today. At present, throughout the world, over 80% of the land that is suitable for raising crops is in use (sources: FAO and NASA). Historically, some 15% of that has been laid waste by poor management practices. To feed so many people, we may require expanding farmland at the expense of forests and wilderness, or finding ways to radically increase crop yields.
What can be done to avoid this impending disaster?
“In order to keep a planet that’s worth living on, we have to change our methods,” says Gertjan Meeuws, of Plant Lab, a private research company in Netherlands.
With population increasing exponentially, farming is moving indoors, even where the sun never shines, where rainfall is irrelevant and where the climate is tailored according to as per crop requirement so that the same can be grown all-round the year. Indoor farming is not a new concept, of course. A wide variety of product, including tomatoes, herbs and spices, has been grown already quite successfully for many years. What is new, however, is the growing need to scale this technology to mass-production, to accommodate the rapidly accelerating migration of people from rural to urban areas. Skyscraper farms have enormous potential to improve both the urban and rural environment in many ways. They “Green” up the concrete jungle, providing more plants and more carbon-dioxide conversion in polluted urban areas. They also eventually allow the repair of ecosystems that have been sacrificed by decades of industrial horizontal farming. Due to fast urbanisation, when we run out of arable land in crowded cities, the solution is obvious: build upwards. The concept modified by dedicating high-rise buildings in urban environments for food purpose, is called vertical farming.
The necessary technology already exists. The glasshouse industry has more than a century’s experience of growing crops indoors in large quantities, says Gene Giacomelli, Director of the Controlled Environment Agriculture Centre at the University of Arizona in Tucson. It is now possible to customise the temperature, humidity, lighting, airflow and nutrient conditions to get the best productivity out of plants year round, anywhere in the world, he says. Besides, a constant flow of air keeping the plants bathed in carbon dioxide, the basis of a vertical farm is hydroponics. Any nutrients and water that are not taken up by the roots can be recycled, rather than being lost into the soil.
Hydroponics: the basis of vertical farming
The basis of vertical farming is hydroponic (water based and soil-less) culture in nutrient solutions. The idea of a vertical farm has been existing at least since the Hanging Gardens of Babylon. The modern idea of vertical farming uses techniques similar to glass houses, where natural sunlight can be augmented with artificial lighting.
The term “Vertical Farming” was coined by Gilbert Ellis Bailey in 1915 when he authored a book with same name. He meant otherwise as he mentioned about farming underground with the use of explosives. Modern day usage refers to skyscrapers using some degree of natural light.
Despommier’s concept of “The Vertical Farm” emerged in 1999 at Columbia University. Dicknson Despommier is now considered to be the ‘Father of Vertical Farming’ and his ideas are being translated in several part of contemporary world. An article, on vertical farming, to some extent was covered in April, 2013 issue of the Soilless Gardening-India magazine, and hence it will not be described here.
Advantages of soilless farming
- Can overcome temporal (seasonal) and spatial (agroclimatic) problems of crops.
- Uses much less water, no percolation and runoff.
- High density cropping. (i.e. more number of plants in small area)
- Faster growth, early harvest/ fruiting and with extended duration or some crops can be grown round the year.
- Bigger yield with better quality and shelf life.
- Less number of field operations for successful crop production.
- Clean hygienic environment.
- Effeicient nutrient utilization.
- Can be grown by landless people on their rooftops/ in windowsills/inside houses or backyards.
- High cost (i.e. initial capital cost, cost to run, energy).
- High maintenance (i.e. constant supervision,) and management.
- Requires specialized knowledge and equipment.
- Pollination is another problem in enclosures for which extra steps by planting attractive flowers around or by the use of some growth regulators.
- Epidemics and infestations can explode into total losses overnight on plant grown in confinement.
Role of light in soilless/ vertical farming
The heart of the high tech vertical farming is lighting which is economically viable. It has been observed that high intensity discharge (HID) and metal halides promote vegetative growth; high pressure sodium (HPS) is used for early flowering. Now a days, the role of variety of LED lights viz red and blue, are being investigated and used for promoting photosynthesis and save energy.
It would appear that the next era of farming would be technological in the hands of elite and rich instead of traditional rural farmers and in multi-storey towers of food and farming, not on soil but from soilless culture. Interestingly, most of the plants indeed do not require soil for their growth and production. The role of soil is only anchorage or as a medium to provide the nutrients acquired through natural mineralization or from supplied fertilizers.
*The author is former Dean, Faculty of Basic Sciences at HPAU and Professor of Plant Physiology, who had been growing hydroponic tomato, bell peppers and strawberry in simple soilless and NFT systems for the last 15 years. Some of the pics related to his work are attached herewith.