HYDROPONICS
Hydroponics is a subset of hydroculture and is a method of growing plants using mineral nutrient solutions, in water, without soil. Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium.
Plants absorb essential mineral nutrients as inorganic ions in water. In natural conditions, soil acts as a mineral nutrient reservoir but the soil itself is not essential to plant growth. When the mineral nutrients in the soil dissolve in water, plant roots are able to absorb them. When the required mineral nutrients are introduced into a plant's water supply artificially, soil is no longer required for the plant to thrive. Almost any terrestrial plant will grow with hydroponics.
Advantages:
Some of the reasons why hydroponics is being adapted around the world for food production are the following:
Today, hydroponics is an established branch of agronomy. Results have proved it to be thoroughly practical and to have very definite advantages over conventional methods of horticulture. There are two chief merits of the soil-less cultivation of plants. First, hydroponics may potentially produce much higher crop yields. AIso, hydroponics can be used in places where in-ground agriculture or gardening are not possible.
Disadvantages:
Without soil as a buffer, any failure to the hydroponic system leads to rapid plant death. Other disadvantages include pathogen attacks such as damp-off due to verticillium wilt caused by the high moisture levels associated with hydroponics and over watering of soil based plants. Also, many hydroponic plants require different fertilizers and containment systems.
Techniques:
The two main types of hydroponics are solution culture and medium culture.
Solution culture does not use a solid medium for the roots, just the nutrient solution. The three main types of solution cultures are static solution culture, continuous-flow solution culture and aeroponics.
The medium culture method has a solid medium for the roots and is named for the type of medium, e'g.. sand culture, gravel culture, or rockwool culture. There are two main variations for each medium, sub-irrigation and top irrigation. For all techniques, most hydroponic reservoirs are now built of plastic, but other materials have been used including concrete, glass, metal, vegetable solids, and wood. The containers should exclude light to prevent algae growth in the nutrient solution.
Substrates:
One of the most obvious decisions hydroponic farmers have to make is which medium they should use. Different media are appropriate for different growing techniques - Expanded clay aggregate, Growstones, Coir, Rice Hulls, Perlite, Pumice, Vermiculite, Sand, Gravel, Wood Fibre, Rock wool, sheep wool, Polystyrene packing peanuts, etc.
Nutrient Solutions:
Plant nutrients used in hydroponics are dissolved in the water and are mostly in inorganic and iconic form. Primary among the dissolved cations (positively charged ions) are CA2+ (Calcium) ; Mg2+(magnesium), and K+(potassium); the major nutrient arrionsln nutrient solutions are No-: (nitrate), Soz-+ (sulfate), and Hzpo-+ (dihyclrogen phosphate).
Many use different combinations of chemicals to reach similar total final compositions. Commonly used chemicals for the macronutrients include potassium nitrate, calcium nitrate, potassium phosphate, and magnesium sulfate .
Various micronutrients are typically added to hydroponic solutions to supply essential elements; among them are Fe (iron), Mn (manganese), Cu (copper), Zn (Zinc), B (boron), Cl (chlorine), and Ni (Nickel).
Chelating agents are sometimes used to keep Fe soluble, and humic acids can be added to increase nutrient uptake.
Organic hydroponics uses the solution containing microorganisms. In organic hydroponics. organic fertilizer can be added in the hydroponic solution because microorganisms degrade organic fertilizer into inorganic nutrients. In contrast, conventional hydroponics cannot use organic fertilizer because organic compounds in the hydroponic solution show phytotoxic effects.
Non-circulating hydroponic methods for growing lettuce which do not require electricity, pumps or wicks. All of the nutrient solution is added prior to planting or transplanting.
Method 1:
In the simplest system, lettuce is seeded in a tapered plastic net pot filled with growing medium and placed in a darkened, 4-liter plastic bottle filled with nutrient solution with the lower 3-cm-portion of the pot immersed in nutrient solution. Plants are automatically watered, because the entire growing medium in the net pot becomes moistened by capillary action. Plant growth reduces the nutrient solution level creating an enlarging moist air space. Meanwhile, the root system expands and continues to absorb water and nutrients. Leaf and semi-head lettuce cultivars are usually harvested at about 6 to 7 weeks after seeding.
Method 2:
A typical expansion of this concept to a commercial scale employs a 14 cm high tank lined with polyethylene sheeting which is filled with nutrient solution and covered with an expanded or extruded polystyrene sheet resting on the tank frame. Lettuce is planted or transplanted into net pots filled with growing medium and placed in holes in the cover. Lettuce seedlings are initially watered by capillary action, and later, by direct root uptake. The crop is harvested before the nutrient solution becomes exhausted.
Method 3:
Another modification of this method is a float-support system in long rectangular raceway tanks. Lettuce is planted or transplanted into net pots placed in a sheet of extruded polystyrene. The cover initially floats on the nutrient solution, ind then, comes to rest on 2 parallel plastic pipes (10 cm diam) resting on the tank floor as the nutrient solution level recedes due to plant growth. The tank is filled with water immediately prior to harvesting and floating rafts may be easily moved to a harvesting station.
WHY INSUBOARDS ARE PREFERRED IN HYDROPONICS ?
EPS boards can become water-logged and covered with algae, but this doesn't happen with XPS boards. As surface layer of fertilizer salts develops when the moisture from the floating EPS boards evaporates, and this wastes both water and fertilizer.
XPS has closed cells & consistent structure without any large air pockets which may prove beneficial to plants when floating on non-circulating nutrient solution. Whereas EPS boards have a more irregular structure and occasional air pockets.
Plants absorb essential mineral nutrients as inorganic ions in water. In natural conditions, soil acts as a mineral nutrient reservoir but the soil itself is not essential to plant growth. When the mineral nutrients in the soil dissolve in water, plant roots are able to absorb them. When the required mineral nutrients are introduced into a plant's water supply artificially, soil is no longer required for the plant to thrive. Almost any terrestrial plant will grow with hydroponics.
Advantages:
Some of the reasons why hydroponics is being adapted around the world for food production are the following:
- No soil is needed for hydroponics.
- The water stays in the system and can be reused - thus, a lower water requirement.
- Hydroponics also saves water; it uses as little us t/r1, the amount as a regular farm to produce the same amount of food.
- It is possible to control the nutrition levels in their entirety - thus, lower nutrition requirements
- No nutrition pollution is released into the environment because of the controlled system
- Stable and high yields
- Pests and diseases are easier to get rid of than in soil because of the container's mobility
- Ease of harvesting
- No pesticide damage . Plants grow healthier
- It is better for consumption
Today, hydroponics is an established branch of agronomy. Results have proved it to be thoroughly practical and to have very definite advantages over conventional methods of horticulture. There are two chief merits of the soil-less cultivation of plants. First, hydroponics may potentially produce much higher crop yields. AIso, hydroponics can be used in places where in-ground agriculture or gardening are not possible.
Disadvantages:
Without soil as a buffer, any failure to the hydroponic system leads to rapid plant death. Other disadvantages include pathogen attacks such as damp-off due to verticillium wilt caused by the high moisture levels associated with hydroponics and over watering of soil based plants. Also, many hydroponic plants require different fertilizers and containment systems.
Techniques:
The two main types of hydroponics are solution culture and medium culture.
Solution culture does not use a solid medium for the roots, just the nutrient solution. The three main types of solution cultures are static solution culture, continuous-flow solution culture and aeroponics.
The medium culture method has a solid medium for the roots and is named for the type of medium, e'g.. sand culture, gravel culture, or rockwool culture. There are two main variations for each medium, sub-irrigation and top irrigation. For all techniques, most hydroponic reservoirs are now built of plastic, but other materials have been used including concrete, glass, metal, vegetable solids, and wood. The containers should exclude light to prevent algae growth in the nutrient solution.
Substrates:
One of the most obvious decisions hydroponic farmers have to make is which medium they should use. Different media are appropriate for different growing techniques - Expanded clay aggregate, Growstones, Coir, Rice Hulls, Perlite, Pumice, Vermiculite, Sand, Gravel, Wood Fibre, Rock wool, sheep wool, Polystyrene packing peanuts, etc.
Nutrient Solutions:
Plant nutrients used in hydroponics are dissolved in the water and are mostly in inorganic and iconic form. Primary among the dissolved cations (positively charged ions) are CA2+ (Calcium) ; Mg2+(magnesium), and K+(potassium); the major nutrient arrionsln nutrient solutions are No-: (nitrate), Soz-+ (sulfate), and Hzpo-+ (dihyclrogen phosphate).
Many use different combinations of chemicals to reach similar total final compositions. Commonly used chemicals for the macronutrients include potassium nitrate, calcium nitrate, potassium phosphate, and magnesium sulfate .
Various micronutrients are typically added to hydroponic solutions to supply essential elements; among them are Fe (iron), Mn (manganese), Cu (copper), Zn (Zinc), B (boron), Cl (chlorine), and Ni (Nickel).
Chelating agents are sometimes used to keep Fe soluble, and humic acids can be added to increase nutrient uptake.
Organic hydroponics uses the solution containing microorganisms. In organic hydroponics. organic fertilizer can be added in the hydroponic solution because microorganisms degrade organic fertilizer into inorganic nutrients. In contrast, conventional hydroponics cannot use organic fertilizer because organic compounds in the hydroponic solution show phytotoxic effects.
Non-circulating hydroponic methods for growing lettuce which do not require electricity, pumps or wicks. All of the nutrient solution is added prior to planting or transplanting.
Method 1:
In the simplest system, lettuce is seeded in a tapered plastic net pot filled with growing medium and placed in a darkened, 4-liter plastic bottle filled with nutrient solution with the lower 3-cm-portion of the pot immersed in nutrient solution. Plants are automatically watered, because the entire growing medium in the net pot becomes moistened by capillary action. Plant growth reduces the nutrient solution level creating an enlarging moist air space. Meanwhile, the root system expands and continues to absorb water and nutrients. Leaf and semi-head lettuce cultivars are usually harvested at about 6 to 7 weeks after seeding.
Method 2:
A typical expansion of this concept to a commercial scale employs a 14 cm high tank lined with polyethylene sheeting which is filled with nutrient solution and covered with an expanded or extruded polystyrene sheet resting on the tank frame. Lettuce is planted or transplanted into net pots filled with growing medium and placed in holes in the cover. Lettuce seedlings are initially watered by capillary action, and later, by direct root uptake. The crop is harvested before the nutrient solution becomes exhausted.
Method 3:
Another modification of this method is a float-support system in long rectangular raceway tanks. Lettuce is planted or transplanted into net pots placed in a sheet of extruded polystyrene. The cover initially floats on the nutrient solution, ind then, comes to rest on 2 parallel plastic pipes (10 cm diam) resting on the tank floor as the nutrient solution level recedes due to plant growth. The tank is filled with water immediately prior to harvesting and floating rafts may be easily moved to a harvesting station.
WHY INSUBOARDS ARE PREFERRED IN HYDROPONICS ?
EPS boards can become water-logged and covered with algae, but this doesn't happen with XPS boards. As surface layer of fertilizer salts develops when the moisture from the floating EPS boards evaporates, and this wastes both water and fertilizer.
XPS has closed cells & consistent structure without any large air pockets which may prove beneficial to plants when floating on non-circulating nutrient solution. Whereas EPS boards have a more irregular structure and occasional air pockets.