and Cowpeas

refugee camp (box 5.1) showed that hydroponics decreased water usage for kale by 82 percent, spinach by 92 percent, and cowpeas by 84 percent compared with conventional farming (WFP Kenya 2020). It also showed that hydroponics uses 1.4 to 6 times less space, has greater yields, and has shorter growing cycles than conventional farming (figure 5.5).

Versatility

Hydroponic farming is possible across diverse climates and agro-ecological zones, including arid areas and urban zones (Heredia 2014). This is because hydroponics can be applied indoors. Growing in greenhouses or other controlled environments separates the production area from the location’s natural ecosystem; therefore, the ecosystem has no impact on the growth of hydroponic plants. As such, hydroponic farming can be done anywhere. This separation of growing from the natural environment also eliminates any environmental harm that agriculture would cause to the natural ecosystem, such as deforestation, monoculture, or any other form of environmental degradation. Thus, hydroponic food production has a minimal impact on natural resources and the environment and can be implemented in cities or on degraded lands.

Producing crops in urban areas minimizes the distance between the food producer and the urban consumer (Bellows, Brown, and Smit 2004). A closer proximity of producers to markets reduces labor, transportation, packaging, and refrigeration requirements, leading to potentially substantial decreases in the use of resources and energy. In the United States, these additional costs account for up to 79 percent of a crop’s retail price (Wohlgenant 2001).

FIGURE 5.5 Hydroponic Space, Water Needs, and Yields for

Producing Kale, Spinach, and Cowpeas

Space

Number of plants Water

Liters Yield/growth

Yield/ growth days Harvest yields

Kale

16 60 49 71

Spinach

49 82

Cowpeas

113 800 1.4–6 times

Source: WFP Kenya 2020. Note: g = grams; kg = kilograms.

3,780 380

4,860

415

3,200

530

Saved 82%

Saved 92%

Saved 84%

21 days stopped producing

51 days 200g

40 days 200g 39 days 3kg

38 days 3kg

32 days 15kg

Shortening and simplifying food supply chains can drastically diminish their environmental impacts, while providing cities and rural areas fresh, highly nutritious produce. A pilot hydroponic project in The Gambia demonstrated some of the benefits of reducing producer-to-consumer distances (Abdoulaye 2009). The project focused 80 percent of its efforts in urban and peri-urban areas, where poverty rates can exceed 40 percent.

Hydroponic systems can be set up in small spaces, such as homes, and large spaces, such as commercial farms. Hydroponic systems are controlled and can be built in any environment. Hydroponic farms have been established in unused or recycled spaces such as parking lots, building rooftops, shipping containers, abandoned warehouses, and even underground tunnels such as sewers or subways. The type of space depends on the type of crop being grown. Hydroponic farmers tend to use smaller spaces to grow herbs and leafy greens because these plants grow quickly, can be continuously harvested, and do not require much space to expand. Therefore, growing herbs and leafy greens in warehouse facilities that are vertically oriented requires little space but can generate lots of produce. Hydroponic farmers often use larger spaces for voluminous plants that require more advanced hydroponic systems with trellises or deep root support. In 2018, the largest hydroponic tomato greenhouse in West Africa, Wells Hosa Greenhouse Farms, opened in Nigeria. Located on 27 hectares of land, it consists of 28 hydroponic greenhouses that are each 5,440 m2. The company aims to produce 4,200 metric tons of tomatoes to meet local and export demand and generate US$6 million in annual income.

Simple hydroponic systems do not require much labor. Reuters tells the story of Venensia Mukarati, a Zimbabwean woman who was able to set up and operate her own hydroponic system. Ms. Mukarati did this because she wanted to grow produce for her family but did not have land. Through a simple online search, she learned how to grow vegetables on her deck using a small hydroponic system that she imported from Cape Town for US$900. Ms. Mukarati quickly realized that hydroponics could be a profitable venture. She learned that she could harvest vegetables within six weeks with hydroponics instead of 10 weeks if she were using conventional soil-based agriculture. She started by growing 140 plants but now produces 2,600 plants per cycle, including herbs, lettuce, spinach, and cucumbers in two makeshift greenhouses. After two years, she scaled up her production fourfold by building larger greenhouses on 2,600 m2 of land. By January 2020, Ms. Mukarati was also training others in hydroponics and selling a hydroponic “starter pack” for US$200 that she designed herself. She earns US$1,100 per month, or about 14 times what some government workers earn. She established this system on her own and requires little help to maintain its operations (Dzirutwe 2020).

Pest Management

Hydroponic plants are usually more pest resistant than soil-based plants and do not need chemical herbicides or pesticides. Pest infestations can destroy

crops, and pesticide use is a health and environmental concern for many consumers. In hydroponic farming, pesticide use is usually unnecessary. A study by Treftz and Omaye (2016) compares strawberry growth performance in hydroponic and soil systems. It shows that 80 percent of hydroponic strawberries survived compared with only 50 percent of soil-grown strawberries. The study cites pest infestations as the cause of the lower plant survival rates in soil-based farming (Treftz and Omaye 2016). This suggests that using hydroponic systems on a large scale could reduce pesticide usage, reducing the farmer’s input costs.

Energy Efficiency

Hydroponics is feasible in areas with unreliable seasonal sunlight. Several studies have shown that both light intensity and light quality are important for plant growth and development (Neff, Fankhauser, and Chory 2000; Fukuda et al. 2008). Plants use light for photosynthesis and to signal the start and end of the growing season. Artificial light can replace sunlight in indoor plant growing systems. However, reliance on artificial light increases electricity use and energy costs.

Hydroponics can reduce carbon emissions if the system uses renewable energy sources or natural heating. Addressing electricity needs is one of the key trials facing the hydroponic industry, particularly in northern latitudes. High-tech hydroponic systems tend to use a lot of energy since they usually incorporate lighting, pumping, heating, and air moderation systems. Producers can mitigate this by locating hydroponic facilities in areas with access to inexpensive renewable sources of energy, such as wind, solar, or geothermal power (Barbosa et al. 2015). Increased greenhouse gas emissions from high energy use are partially offset by reduced transportation needs. Using greenhouses to store natural heat energy can also reduce energy needs. Greenhouses located in more moderate climates, such as climates closer to the greenhouse set point temperature, will experience a lower energy demand. In certain climates, heating and cooling systems may not be required but instead replaced by a passive ventilation system, thus reducing the overall energy demand considerably (Barbosa 2015).

Benefits for African and FCV Countries

Hydroponic technologies are climate-resilient and mitigate climate-related risks. Climate change is exacerbating fragility in FCV countries (World Bank Group 2019). In East and Southern Africa in 2020 and 2021, a hotter climate was linked to swarms of locusts infesting subsistence crops, especially affecting Kenya’s nearly 9 million smallholder farmers (World Bank Group 2019). Hydroponics, which can be established anywhere in climate-controlled conditions, is not exposed to temperature variations and can hedge against the risk that climate change and secondary effects, such as pests, pose to traditional field crops.