Nutrient Film Technique

The challenges and potential of aquaponics production is still an unexplored area of study in  India. Aquaponics is a combined method of farming by bringing aquaculture and hydroponics together in a single system. There has been a positive change in Aquaponics farming as the popularity of the system increased in the last few years in our country.

By 2050, the world’s population is estimated to increase to 9 billion. The expansive numbers of people are expecting to rely on agricultural sector including farming, fisheries, woodcrafts, and livestock. Natural calamities and crisis affect millions of people who depend on the primary sector. For reducing poverty and attaining food security, expansion of agriculture sector is the most efficacious means. Small farmers are the major contributors to the World’s food, but they are the poorest people in the developing countries. 70 per cent of the people living in the rural area depends on Agriculture even today, however, one-fourth of the population find it difficult to meets their daily nutritional requirement.

Indian farmers are exposed to many challenges resulting from low agricultural growth, sustainability concerns, and land degradation, as a large area of farmland has become infertile due to the overuse of fertilizers and pesticides. Conventional farming methods because of large usage of fertilizers for growing crops degraded the quality of the soil and local water sources. It is high time to overcome these challenges through innovative farming methods. The technological and scientific advancement in the field of agriculture has opened a new era for the design and development of modern devices for plant health monitoring. Aquaponics farming is a solution to overcome some of these challenges to an extent if the farmers are able to maintain the system with proper care and technical support.

Although aquaponics has received considerable attention in foreign countries, Indian farmers are relatively new to this system. However, there has been a gradual increase in awareness of this system over the past few years in the country.

Aquaponics is an integrated method of growing fishes and crops in a re-circulating system. In other words, it is an integrated system of re-circulating aquaculture and hydroponics in one production system. Water from the fish tank that contains fish excretes cycles through grow beds where plants are grown, which is nutritious for the plant's growth and plants' filter the water flowing into the fish tank to keep the fish healthy. The main elements for aquaponics are the fish tank and grow beds with a small pump that filters water between the two. The success of an aquaponics system requires proper maintaining of the plants, fish, and nutrients that gives a well-balanced and interdependent relationship. Aquaponics farming is suitable for farmers who have fewer land holdings and in areas where water is scarce. Crops grown in aquaponics have less damage and are able to grow in denser climate.

In India, the land holdings used for agriculture are limited to less than 0.2 hectares. As a result, the small-scale agriculturists aim to maximize production within the minimum resources. Growing awareness of consumers on the excessive use of fertilizers and pesticides are leading to a trend that favours organic farming. The interest of the young generation to produce vegetables and other regional cultivations on a small scale within the available land area has further boosted the scope of organic farming. Organic farming is a concept with considerable thrust on integrated systems wherein a major part of inputs required for farming is raised within the system. Integrated farming uses wastages and sub-products of a particular cultivation for the use of other. It usually includes growing and breeding of cattle, duck, fish etc. This is a globally accepted technology and adapted to a greater extent by the Indian farming community. Within the available space that includes terrace and balconies of apartments, Indian households have started taking up aquaculture in small tanks along with vegetables in separate grow beds. The method of recycling wastewater and making it available for further use has increased its demand all over this time. Integrating hydroponics (the method of growing plants without soil) and aquaculture has been given more importance in the current agricultural scenario.

As the aquaponics system has many advantages and increases the productivity within a short time period, it has gained popularity in several states of India in recent times. State Fisheries Departments are promoting aquaponics by providing training programmes and technical support to the farmers. It is an effective means of growing food that helps to maintain sustainability, as it requires only 10 per cent of water and no use of chemical fertilizers as compared to the traditional farming method.

Aquaponics as a commercial venture is evolving in India. People are discovering it as a promising avenue to rely upon as a dependable source of livelihood. Further, small and medium-sized units are more efficient in managing costs and realizing higher net income per unit area compared to large units. However, a variety of factors such as lack of training, inadequate technical guidance, ignorance of market pricing and uncertainties about the market demand of the product, are some of the reasons for incurring losses. These challenges can be overcome by providing technical sessions about the working of the system and by making consumers aware of the benefits of organic products. In Hydrilla workshops, apart from taking participants through Aquaponics farming methods, fish and plant health management, system design aspects, we take through the analysis of marketing strategies like identifying right crops based on market demand, direct selling to neighbourhood consumers, indirect selling to wholesalers, restaurants and grocery stores.

In general, the success of aquaponics farming relies upon the local markets, climatic and geographical conditions. An important feature of aquaponics systems is their ability to reduce the local impacts that arise from the nutrient discharges. Due to the dynamic characteristics of the aquaculture industries, it is expanding rapidly in recent times. Hence, more emphasis should be given on high productivity, intensive systems with similar low global impacts rather than focusing completely on the reduction of local impacts.

Aquaponics has immense potential to be the forerunner in the next phase of sustainable aquaculture.

Growing peppers in aquaponic units: There are many varieties of peppers, all varying in colour and degree of spice, yet from the sweet bell pepper to the hot chili peppers (jalapeno or cayenne peppers) they can all be grown with aquaponics. Peppers are more suited to the media bed method but they might also grow in 11 cm diameter NFT pipes if given extra physical support.

Growing conditions: Peppers are a summer fruiting vegetable that prefers warm conditions and full sun exposure. Seed germination temperatures are high: 22–34 °C. Seeds will not germinate well in temperatures 30–35 °C lead to floral abortion or fallout. In general, spicier peppers can be obtained at higher temperatures. The top leaves of the plant protect the fruit hanging below from sun exposure. As with other fruiting plants, nitrate supports the initial vegetative growth (optimum range: 20–120 mg/litre) but higher concentrations of potassium and phosphorus are needed for flowering and fruiting. 

Growing instructions: Transplant seedlings with 6–8 true leaves to the unit as soon as night temperatures settle above 10 °C. Support bushy, heavy-yielding plants with stakes or vertical strings hanging from iron wires pulled horizontally above the units. For red sweet peppers, leave the green fruits on the plants until they ripen and turn red. Pick the first few flowers that appear on the plant in order to encourage further plant growth. Reduce the number of flowers in the event of excessive fruit setting to favour the growing fruits to reach an adequate size. 

Harvesting: Begin harvesting when peppers reach a marketable size. Leave peppers on the plants until they ripen fully by changing colour and improve their levels of vitamin C. Harvest continually through the season to favour blossoming, fruit setting and growth. Peppers can be easily stored fresh for 10 days at 10 °C with 90–95 per cent humidity or they can be dehydrated for long-term storage.

pH: 5.5–6.5

Plant spacing: 30–60 cm (3–4 plants/m2, or more for small-sized plant varieties)

Germination time and temperature: 8–12 days; 22–30 °C (seeds will not germinate below 13 °C)

Growth time: 60–95 days

Temperature: 14–16 °C night time, 22–30 °C daytime

Light exposure: full sun

Plant height and width: 30–90 cm; 30–80 cm

Recommended aquaponics method: media beds

Reference: http://www.fao.org/3/a-i4021e.pdf

• Growing hydroponics lettuce is one of the easiest and the best ways to start hydroponic gardening.
• Lettuce is a simple to grow all round plant that can ensure you get great results when grown in soil, as long as you keep pests off it.
• This is where growing lettuce hydroponically will make perfect sense and will be a terrific first task for any hydroponic setup.
• Lettuce hydroponics will typically look after themselves and do not need a lot of nutrients as other heavy feeding plants like tomatoes.
• It’s obviously still a great practice to check out your growing hydroponic lettuce plants every day for pests or other problems, though these problems are considerably decreased with hydroponics, particularly indoor hydroponics.
• Actually, the only issue you could come across when growing hydroponic lettuce at home is size.
• Lettuce is in high demand and has a high value in urban and peri-urban zones, which makes it a very suitable crop for large-scale commercial production.

Note: -

• Check lettuce for signs of downy mildew, powdery mildew or gray mold and get rid of any infected plants.
• Water that’s heavily chlorinated can lead to issues with lettuce. You should use lightly chlorinated city water or well water.

Lettuce varieties: -

Lettuce can be characterized based on their leaf and head formation.

Crisp head or iceberg: -

• Crisp head lettuce, more commonly known as iceberg, has a tight head of crisp leaves. Often found in the local salad bar, it is actually one of the most difficult lettuce varieties to grow. This lettuce variety is not fond of hot summer temperature or water stress and may rot from the inside.
• Start iceberg lettuce via seed directly sown 18-24 inches apart or started indoors and then thinned 12-14 inches between heads. Some iceberg lettuce varieties include Ballade, Crispino, Ithaca, Legacy, Mission, Salinas, Summertime and Sun Devil, all of which mature in 70-80 days.

Romaine or Cos: -

• Romaine varieties are typically 8-10 inches tall and upright growing with spoon-shaped, tightly folded leaves and thick ribs. Colouration is medium green on the exterior to a greenish white inside with the outer leaves.
• Sometimes being tough whilst the interior foliage is tender with wonderful crunch and sweetness. Different types of this lettuce are Brown Golding, Chaos Mix black, chaos Mix white, Devil’s Tongue, Dark green Romaine, De Morges Braun, Hyper Red Rumple, Little Leprechaun. All of which mature within around 70 days.

Butterhead, Boston or Bibb: -

• One of the more delicate varieties of lettuce, Butterhead is creamy to light green on the inside and loose, soft and ruffled green on the exterior. These different types of lettuce may be harvested by removing the entire head or just the outside leaves and easier to grow than crispheads, being more tolerant of conditions.
• Less likely to bolt and rarely bitter, the butterhead lettuce varieties mature in about 55-75 days and spaced similarly to the crispheads. These varieties of lettuce include Blushed Butter Oak, Buttercrunch, Carmona, Divina, and Yugoslavian red.

Growing Conditions: -

• Lettuce is a winter crop. For head growth, the night air temperature should be 3-12°C, with a day temperature of 17-28°C.
• The generative growth is affected by photoperiod and temperature extended daylight warm conditions(>18°C) at night cause bolting. Water temperature >26°C may also result in bolting and leaf bitterness.
• The plant has low nutrient demand; however higher calcium concentrations in water help to prevent tip burn in leaf in summer crops.
• The ideal PH is 5.8-6.2. but lettuce still grows well with a PH as high as 7, although some iron deficiencies might appear owing to reduced bio-availability of this nutrient above neutrality.

Growing instructions:

• Seedlings can be transplanted in units at three weeks when plants have at least 2-3 true leaves. Supplemental fertilization with phosphorous to the seedlings in the second and third weeks favours root growth and avoids plant stress at transplant.
• Take care not to damage the roots of plants during transplanting because such damage will make the plant susceptible to disease infection.
• It is advisable to transplant the plant in the late afternoon to prevent them becoming stressed in the heat of the day under high UV conditions.
• The transplant will begin to adapt to the new location at night and roots will start to grow into the solution below.
• Make sure the plants base is touching the flow of nutrient solution below when transplanting.
• To achieve crisp sweet lettuce, grow plants at a fast pace by maintaining high nitrate levels in the unit. When air and water temperatures increase during the season, use bolt -resistant(summer) varieties. If growing in media beds, plant new lettuces where they will be partially shaded by taller nearby plants.

Lighting: -                                      

• Lettuce grows up vigorously with fluorescent lighting. It would obviously grow far better with the more expensive lighting specially created for hydroponics, like HID and some of the latest LED grow lights for indoor plants.
• However, regarding cost-effectiveness, from the viewpoint of the small-scale grower, fluorescent lighting is the best.
• These are cool weather crops, so too much heat can, in fact, delay germination.

Harvesting Hydroponics lettuce: -

Hydroponics harvesting depends on the following factors

• First, this will depend on what type you are growing. Romaine takes up to 85 days. Bibb and Loose-leaf lettuce can take 45 to 55 days.
• It has to do preference, growing lettuce indoors then you have to manage the environment and prolong your harvest.
• The majority of hydroponic lettuce production systems created around two ideas, either the floating raft system or the nutrient flow technique (NFT) system.
• The floating raft method is of particular interest since it is very affordable and can produce a lot of hydroponic lettuce.
• One of the major issues with raft systems is that the hydroponic lettuce nutrients solution is continually stagnant and will require that you use pumps to circulate water and produce important aeration.
• If the roots are not getting the precious oxygen, floating raft systems experience substantial loses of crops in the form of nutrients.

Below are some types that work well in hydroponics and with indoor artificial lighting:

• Royal Oakleaf is a darker green variety of lettuce that does extremely well in hydroponic growing systems and is also resistant to heat.
• Tango grows perfectly in cooler environmental only.
• Red Fire is a deep red, loose leaf variety that’s ideal for both warm and cool climates.
• Green Ice is a variety of green loose that offers a long picking season.

Hydroponic romaine lettuce also does well though it usually takes a little bit longer to attain maturity.

Tips: -

• When you harvest lettuce with the roots attached, it will prolong storage life by two to four weeks.
• To prevent getting water mold such as Pythium or Phytophthora in your hydroponic lettuce system, use bleach to sanitize the tray between plants. If the lettuce gets infected, the plant is a loss.

 

 

 

 

What is pH?

pH is a measure of the relative concentration of hydrogen ions (H+) to hydroxide ions (OH-). The greater the number of H+ ions in relation to OH- the more acidic the solution becomes. The greater the ratio of OH- ions to H+, the more basic the solution becomes. PH is measured on a scale of 1-14. A reading below 7 means that there are more H+ ions and a reading above 7 indicates more OH- ions. At pH 7 there are the same number of H+ ions as OH- ions so the pH is neutral, neither acid nor base.

 

 

 

 

 

 

 

 

 

Acids and Bases

Any substance that increases the concentration of hydrogen ions (lowers the pH) when added to water is called an acid. A substance that reduces the concentration of hydrogen ions (raises the pH) when added to water is called a base or an alkali. Some substances enable solutions to resist pH changes when an acid or base is added. These substances are called buffers. Buffers are very important in helping to maintain a relatively constant pH in a feeding solution and in the root zone after the water has been applied to the crop. Most greenhouse water supplies have sufficient alkalinity that they require routine acid addition to correct the pH to the normal 5.8-6.2 feeding range. At this level, the irrigation water tends to have a neutral effect on media pH, although this depends on the buffering capacity of the media. Some growers use very pure water from rain and surface sources. In these situations, they may need to apply a combination of acid and base materials to stabilize and buffer the pH.

Why does pH Matter?

Improper management of media pH can result in poor growth and reduced plant quality in greenhouses and nurseries. The pH or soil reaction has a primary influence on the solubility and availability of plant nutrients. Many crops have a narrow range of pH tolerance. If the pH of the soil medium falls above or below this tolerance zone, they may not grow properly due to nutrient deficiency or toxicity.

The availability of most fertilizer elements is affected to some extent by the media pH. Calcium and magnesium become more available as the pH increases, while iron, manganese, and phosphorus become less available. A one-unit pH drop can increase the solubility of manganese by as much as 100 times, and the solubility of iron by as much as 1000 times.

Why Adjust Irrigation pH?

By carefully modifying the pH and alkalinity of your irrigation and feed solutions, you can help maintain the desired plant growth and quality. There are other reasons to monitor and control pH in your irrigation water and nutrient solutions: 1) Solution pH affects the availability of nutrients. 2) Correct pH helps ensure dissolved fertilizer concentrates remain in solution when mixed in the water supply. 3) Acid injection can be used to neutralize excess alkalinity in water supplies.

Understanding The pH Scale

The pH scale measures the relative concentration of Hydrogen Ions (H+) and Hydroxyl ions (OH-) in a solution. Technically, the pH of a solution is defined as a negative logarithm of the hydrogen ion concentration. The ‘p’ is the mathematical symbol for a negative logarithm and the ‘H’ is the symbol for hydrogen. The pH scale measures this, and places a value on it ranging from 0 to 14. Since it is a log scale, each number on the scale is 10 times greater (or smaller) than the next. A lower pH number corresponds to a higher concentration of hydrogen ions (H+) relative to hydroxyl ions (OH-). A higher pH number corresponds to a relatively lower concentration of hydrogen ions

Measuring pH

There are several methods available for measuring pH, but the most useful and practical is an accurate pH meter. Follow the instructions included to preserve the accuracy and life of your instrument. These meters typically use a liquid filled glass probe, although some are now using flat sensor technology.

Water and nutrient solution samples can be measured directly or preferably after a few hours of settling time. Dissolved CO2 in water supplies can cause slightly lower readings until the sample has come to equilibrium with the air. When testing media, freshly mixed samples of media should be watered and allowed to stand for 24 hours before a reading is taken to release some of the lime and fertilizers. The preferred method for testing media pH is to obtain several representative samples of a crop and to measure each separately. Multiple measurements give greater accuracy in reading, and shows the degree of variability of pH across several locations. A saturated media extract or a 1:1 soil to distilled water ratio is fine for measuring media pH.

Factors Affecting pH

These variables can affect the final pH, the rate of pH change, and the amount of modifying action required. They include the effects of:

• Soil temperature
• Fertilizer materials (may raise, lower or buffer pH)
• Soil amendments such as gypsum, sulfur and lime
• Root volume & metabolic activity
• Soil microorganisms
• pH and alkalinity of the irrigation water
• Leaching fraction
• Buffering capacity of both the soil medium and the irrigation source
• Media cation exchange capacity