On the ground, or off the ground ...?
Most agricultural areas are no longer as productive as they once were, due to lack of water, low soil fertility, space, the effects of Climate Change, etc. For this reason, technological alternatives have been sought that allow cultivating and developing productive management efficiently.
In the new agriculture, which is planned in an industrial way and that is based on the use of new technologies, the concept of agriculture out of soil, or hydroponics, as some call it, is extended.
The reasons to choose this way of handling crops are several and varied, in Peru they can be caused by the low or different quality of their soils and a better use of water; in Mexico, for the control of weeds or pathogenic soil diseases; or in Chile for all the previous ones.
Let's not forget that a plant is a living being, which has autotrophic qualities, that is, it has the capacity to produce its own food. The centuries of studies have been able to solve the questions about their growth and demonstrate that it is from the water from which their development process is born.
Off-ground agriculture also arises because most agricultural areas are no longer as productive as they were at some point, due to lack of water, low soil fertility, space, the effects of Climate Change, etc. For this reason, technological alternatives have been sought that allow the cultivation of quality products in small or large spaces and that allow the development of productive management efficiently.
Who was first?
In the history of man, hydroponic cultivation predates cultivation on land, and its history is as old as human civilization. The term hydroponics, which means water that works, was coined by Professor William Grike in 1929 and there are different theses in relation to its exact origin, some place the hydroponics in Babylon and its hanging gardens, but research and scientific discoveries show that it was in China and Egypt where it began to be implemented as a series crop, with productive purposes for human consumption.
It was at 1600 when one of the first controlled experiments was carried out, with measurable variables and isolable elements, where the Belgian scientist, Jan Baptista van Helmont, shows that it is from water, and not from the soil, that plants get the nutrients they need. they collaborate in their growth and productive development.
Finally, it was the war, specifically the Second World War, that spread soilless agriculture throughout the western world as a commercial or industrial agricultural management, because the allied forces developed them in their facilities to meet the needs of vegetables and fruits of its numerous troops in combat.
Substrates ...
The concept of agriculture without soil is the combination of a set of techniques and technological elements that replace the soil and that allow the design of structures with the objective of taking advantage of and favoring suitable environmental conditions to produce the crops.
This management technique anyway needs an anchoring for the plant, a medium in which it is held, a substrate. With the technological development formulas of the most varied forms and contents have been created, to use them according to the needs of size, variety, or phenological state of the plants and to better satisfy the needs of nutrients, temperature, respiration and humidity.
The substrate must be inert and the fundamental thing is its ability to retain moisture, because this determines the possibility that the plant has the necessary nutrients available to carry out its metabolic processes of photosynthesis, respiration and reproductive processes.
This moisture retention depends largely on the granulometry of the substrate, which is mainly determined by the particle size or the porosity of the particles. The higher the moisture retention rates of the chosen substrate, the less necessary or frequent will be the risks.
There are a number of organic and inorganic substrates that can be used for the development of crops without soil, some of them are:
Organic substrates
Sawdust is a substrate that has a moisture retention of an 54%, which is ideal for temperate and dry climates, although it must be subjected to a process of elimination of toxic substances.
Coconut fiber has a moisture retention of 57% and a high ratio of carbon and nitrogen, which allows it to remain chemically stable.
The rice husk, whose main function is to promote the oxygenation of the substrate, must also go through a process of chemical or anaerobic disinfection, in order to eliminate small particles, as well as fungi, insect larvae or other microorganism that may cause contamination to the culture.
The peat moss, which is a material that has characteristics similar to those of coconut fiber. It does not require any process and is widely used for its characteristics of excellent moisture retention, close to 70%.
The peat, which is a spongy mass of vegetable origin, rich in carbon, and with a high moisture retention.
Inorganic substrates
The pumice stone, which is of volcanic origin and has an 38% water retention, also has a good durability and is completely free of microorganisms.
The gravel is composed of small pebbles and particles from quarries that provide excellent aeration, but without much moisture retention.
The river sand has a water retention capacity of 56% and it is recommended to use it in its coarse form.
Perlite is an aluminum silicate of white or leaden volcanic origin, which has a moisture retention of 63%. Its great advantages are its ability to maintain a constant humidity throughout the root zone, as well as excellent aeration capacity due to its porosity.
Sometimes synthetic substrates are used, such as synthetic polyethylene or polystyrene foams, which are used as a filler material, to oxygenate and decrease the weight of the substrates, or to mix with other elements.
Blueberries out of ground
The different varieties of blueberries develop preferably in acid soils, which have a pH between 4,5 and 5. Producers who plant them directly in the soil amend it with granulated sulfur or peat to lower the pH and be able to grow them productively. However, those who grow blueberries in pots or bags do not have to amend the soil, but they should be concerned about providing an acid growth medium for their plants.
Advisable mix
For blueberries grown in pots and on the basis of substrates, the University of Wisconsin recommends using a mixture of a part of pine bark and a part of sphagnum moss, or peat moss, in English.
It also suggests an alternative mix of two parts of coconut fiber, plus two parts of sphagnum moss and one part of perlite.
It is not advisable to mix organic or inorganic substrates, nor to fill pots with soil, even if it is mixed.
In the case of blueberries, which have superficial roots and require frequent watering, but also have the quality of little growth if the soil is saturated or excessively humid, substrates without soil allow them to receive optimal levels of moisture, and a drainage suitable.
The optimum percentage of aeration varies between an 20% and an 30% volume of oxygen available in the substrate, after it has been saturated with water and has finished draining. During the whole process the root must have adequate respiration and for this reason it is important to choose a substrate with a stable structure, very porous and complementary aeration, since this way we will avoid the danger of lack of oxygen in the root zone.
Pots
Regarding the pots, the most appropriate are the rigid ones, because they keep the plant and the substrate in the same position, without sudden movements that affect its root. In the case of bags, the most appropriate is that of 40 liters, and in places of high radiation it is advisable to have the black bag inside and white on its outer surface, because it maintains the temperature at the root but prevents more radiation from entering. of the advisable thing, avoiding the radicular heating.
The pot must be isolated from the ground, for which it is advisable to place it on a solid support or base, and this in turn on a carpet or alveolar cover that isolates the soil from the crop.
Precisions
The nutrition of the plant in soil is difficult to control due to the variability of the environment, however in the substrate it has stability and allows to monitor and correct it.
The spacing of the plantations in soil limits the fertility and the density of the plantation is lower, however outside of the soil a high density and a greater use of space and light is achieved.
The control of weeds in crops in soil is almost impossible or very difficult, however, in the modality without soil its existence is much smaller, almost non-existent.
Diseases or pathogenic biological agents are recurrent in crops in soil, a threat that does not exist in the fruit that replaces the soil.
Regarding water, in soil fruit growing there is a general tendency to stress due to lack or poor distribution of water resources, which does not happen in fruit management without soil, because hydroponic technology is based on the permanent disposal of water applied to rational and balanced way for an efficient use of the resource.
Finally, the substrates used in the fruit growing out of soil provide greater oxygenation to the plants, in comparison to that obtained by the crops in natural soils.
Agriculture is the productive process that has acquired the use of new clean technologies more quickly, and with greater responsibility assumes the need to adapt to Climate Change. In recent years there are new concepts of agriculture: sustainable, protected, or precision, among others, and all point to a better use of resources, which are increasingly scarce, and a better relationship between man and the environment natural, in a vision of the productive process that is sustainable.
Source: Blueberrieschile.cl - Blueberriesconsulting.com
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