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Over the last 30 years, increased urbanization and population growth around the world has resulted in a shrinking availability of high-quality farmlands. As space continues to dwindle, more farmers have sought ways to increase harvesting speed as a way to meet the rising global food demands from consumers. Unfortunately, the average yield-produced-per-unit of many farms is simply not enough due to the traditional growth rate and seasonality of crops. To address this, many agriculturalists are now looking into the potential of aquaponics as a faster and more efficient technique for growing crops on a commercial scale. But do plants grow faster in aquaponics? Should you abandon soil gardening all-together and go completely soilless?
Many studies suggest that aquaponic plant growth is relatively faster than traditionally planted crops in soil or other cultivation methods. In fact, growers using this system have seen noticeably higher yields, as well as more frequent harvesting throughout the year due to its’ controlled environment. However, aquaponic systems are not perfect and can have their own set of limitations.
In this article, we will discuss how aquaponic plants compare to soil-grown crops when it comes to growth and the factors that directly affect this process in an aquaponic system.
Aquaponics vs. Soil Growth Rate
A study published in the Semantic Scholars in the year 2014 supports the claim above as it compared the growth performances of taro plants in aquaponics and other systems. The results show that the fastest growth of the taro plant recorded is through using aquaponics, followed by soil, and lastly, hydroponics. The crop’s growth rate and the biomass is a product of the continued supply of nutrients it gets from the fish waste.
If a plant’s growth is fast, just like the taro we have discussed, the average yield of the crop per annum would also be high because there’s a possibility of harvest multiple times a year. This assumption is the focus of the research of Love et al. published in Science Direct, about commercial aquaponics production and profitability. In their study, they found that through this soil-less planting method, the farmers who served as their respondents recorded 452,000 kg (997,000 lb) of produce for the last 12 months.
Factors Affecting Plant Growth in an Aquaponic System
To understand why plants grow faster in aquaponics, let us examine some of the factors that affect the growth rate in this system.
All the essential nutrients needed for the plants to grow fast comes from fish waste in this set-up. Fish waste is a good source of nitrogen, phosphorous, potassium, calcium, magnesium, and sulfur. Since this is available all the time through the water system, aquaponic plants tend to grow faster and healthier.
Aquaponic systems use only 10% of the water needed by soil-based crops, but they are very rich in nutrients. Below are some of the things that should be considered to maintain good water quality and ensure a fast growth rate.
The suggested pH water level in an aquaponic system is 5.5 to 7.5. If the pH level exceeded the normal range, the plants wouldn’t absorb nutrients even though they are present in the water because of nutrient blocking. However, the recommended pH will always depend largely on the fish and plants that are being cultivated in the system.
Aquaponic plants need oxygen to avoid root-rot and fungus growth. The correct amount of dissolved oxygen that the system requires is typically not greater than 3 mg/liter.
Most aquaponic vegetables grow between 18-30 °C; however, growers should also keep in mind that different plants require different temperatures most of the time. For instance, leafy green vegetables can grow faster between 14–20 °C. The Food and Agriculture Organization of the United Nations suggests that the local seasonal planting practices should be followed to avoid too many temperature adjustments.
Light is primarily needed for photosynthesis, aside from water, carbon dioxide, and oxygen. Placing the aquaponic unit in an area directly hit by sunlight is necessary for the plants to get energy for photosynthesis. Keep in mind that too much sunlight can be problematic for certain breeds of fish and plants.
To convert fish waste into useful fertilizer, it has to go through biofilter or the nitrification process. Since fish produce waste in the form of ammonia, bacteria present in the system will convert them into nitrates that are the direct source of plant nutrients.
Planting design is vital to make sure that each crop receives enough nutrients to grow. Aside from this, it can also maximize garden space and increase production. During the planning phase, growers can draw a layout on a piece of paper, taking into consideration how much space each plant will consume depending on their size.
Balance of fish and plants
For the aquaponic system to produce crops fast, there should be a balanced ratio between the fish and the plants. This way, the plants receive the right amount of nutrients from the fish waste, and in return, the water is thoroughly filtered and healthy for the fish.
Conclusion: Plants grow faster in aquaponics, but…
Growing crops through aquaponics has a lot of advantages including the superior growth rate over soil-based systems and the high amount of yield. This is possible because of the many factors that directly affect plant growth in an aquaponic system have the ability to be controlled. This is often impossible for soil-based gardening techniques. However, soil gardening can also have some benefits, including a lower-barrier to entry and affordable start-up costs.
Many aquaponics practitioners go with a hybrid-gardening approach, in which certain plants will be cultivated aquaponically, while others are grown in soil. This is a beneficial strategy, particularly if you are trying to decide between where to set up your aquaponics bed, and also if budget becomes a concern.