Between the most trendy and interesting in agriculture, we can mention the soilless farming techniques, of which there are two main types:
- Hydroponics (growing plants in water).
- Aeroponics (growing plants in air).
The option to grow plants without soil is not so recent anyway: if the first technical studies date back to the 17th century, growing plants without soil was already done much time before. Hanging gardens of Babylon or Aztec Chinampas are just some examples.
Soilless farming or cultivation, similar to the protected one(like greenhouses, polyhouse), are based on the modification of the environment to the specific needs of plants.
Soilless farming or Soilless agriculture is a technique which allows intensive cultivation even in the case of not very productive soils (for example, with problems connected to the fertility), or when the soil is not very available (for example, in some Asiatic countries).
Many reasons limit the adoption of Soilless farming or Soilless agriculture on a large scale:
– A significant impact of production costs, which still result high regarding the purchase of many expensive productive means such as tools, systems, fertilizers and so on;
– Economical risks connected to the commercialization of products, still not very present on the markets;
– The recycling of solutions used in cultivation;
– The competition with other methods (mainly, the intensive one);
– Techniques still suitable for a limited number of crops.
Soilless Farming – Hydroponic Cultivation:-
Hydroponic is the art of growing plants in water. It could be defined as the technique which allows the development of plants without using the soil, utilizing a support more or less inert come (for example perlite, peat, pietra pumice stone, sand, etc.) as substrate, to which a nutritive solution – that contains elements plants need – is added.
There are Egyptian hieroglyph dating back to many years before Christ which already describe the growth of plants in water. Anyway, it became a technique just in 1930, when W.F. Geriche of California University California transferred his laboratory knowledge on a commercial scale. The first practical application of big importance, anyway, dates back to the 40s during the World War II, when U.S. soldiers, fighting in much straightened conditions, solved the problem of fresh vegetables supplying using hydroponic techniques.
These primordial approaches, scarcely diffused, kicked off to scientific researches and development of a huge range of agricultural techniques, especially from the 70’s, many of them have already found a large application on a commercial scale in several countries.
Hydroponic systems with the largest application are substrate cultivation which can
use alternative materials destined to support plants. Among the most used materials we can mention:
Peat: produced from the very slow decomposition of some vegetable species, it has low removal problems thanks to its easy biodegradability and low system and managing costs.
Perlite: it is a particular type of volcanic rock, able to expand up to 20 times larger than its original volume; it has a good draining and oxygenation
Rock wool ( or grodan ) : it is volcanic rock ( basaltic ), which – properly treated – can reach a volume larger than 90 times the initial one. Yet it implies remarkable removal problems in the end of every cultivation cycle;
Coir: it is one of the most practical and efficient materials and is ecological and recyclable; unlike peat as time goes by it still remains soft, so helping an easier development.
Hydroponic consents to recover cultivation areas handicapped by ‘negative’ weather, to overcome difficulties connected to the physiological tiredness of soils, to amply crops calendar with a continue offer and to obtain a better standardization of products.
Problems which this technique has are connected to financial, logistic and environmental factors.
Financial factors: current hydroponic methodologies involve cultivable soil waste ( the so-called unproductive tares ) , which could arrive up to 40-50% of protected surface, element that united to the high cost to carry out and manage the systems leads to a not negligible heaviness of production costs.
Environmental factors: release of chemical polluting elements in the soil, after the use nutritive solution, besides the difficult removal of support materials used (removal with very high costs, above all in the case of rock wool).
Logistic factors: systems able to definitely avoid both seaweeds formation and roots rot due to the lack of oxygen aren’t implemented yet.
Further problems are then connected to the technical preparation of farmers.
Yet, various factors make us think to a next big development of these soilless farming or soilless agriculture techniques:
– The increasing technological development (just thinking to the use of fresh vegetables in space stations) ;
– Development projects for the 3rd world;
– The low availability of soil where desertification and urbanization are advancing.
A proper technical assistance is needed, in order to guide farmers to the application of these new methods, so to implement simple and economically effective operational systems (which get over the inconvenient of high investment costs and of high specialization level of farmers) .
World-wide in the last few years hydroponic has registered huge progresses as a mean of intensive production. The Netherlands, besides a large number of farmers, has an already undisputed tradition in this sector. In Great Britain, France, Belgium and Japan the Soilless farming or soil-less agriculture is now a reality, while in Spain and Greece is in a strong phase of expansion.
Soilless Farming – Aeroponic Cultivation:-
With aeroponics, very advanced cultivation technique, plants aren’t growth in the soil, but they are placed on specific perforated panels destined to support plants. The development and growth of plants happen in plastic tubes through which nutritive solutions pass: plants roots are exposed to the air and have no contact with any kind of substrate, both natural and artificial.
Growing time of plants is the same of traditional cultivation on soils, but without interruptions (no rest period, typical of soils) and is independent from the seasons (continuous cycle) with a high production yield.
This kind of cultivation allows to use the whole greenhouse volume and to modify nutritive solutions parameters in order to obtain the better crop results.
Currently aeroponic systems are mainly used in Australia, in Canada e in some of the United States, while in Europe and Asia is still a novelty. Although it has an elevated theoretical content, it is mainly turned to the solution of individual problems and lacks of a single reference able to standardize the various partial results obtained and to transfer them in a productive system also usable by non-super-specialized people.
However it is subject of further developments and improving, so that this technique could help, in the next decades, to solve hunger problems by the increasing of agricultural production and their creation in uncultivable areas (such as the rocky or desertic ones ) . For this purpose FAO is dedicating itself to export this technique in 3rd, above all in the ones where water is a very.
Anyway, the full application of these techniques is obstructed by many factors, such as:
- High costs of systems;
- High energy consumption;
- Problems of luminous competition between plants, mainly in those systems which try to reduce at maximum the waste of cultivable surface;
- Poor adaptation of systems and nutritive solutions regarding the needs of different vegetable and flower species;
- Solutions too complicated to manage;
- Computerized control of productions;
- Hardly usable for the “average” farmer “.
In the world, aeroponic cultivation is mainly used to grow the following vegetable varieties: tomato, pepper, eggplant, zucchini, cucumber, lettuce, radicchio, cauliflower, broccoli, basil, sage, melon, strawberries for the horticultural ones;
Bottom Line of Soilless Farming:- No doubt soilless farming will be gaining lots of popularity in near future.