than other vegetable markets. The examples described in the chapter, in Turkey and West Bank and Gaza, describe profitable operations. Other cost-benefit analyses of hydroponic systems have focused on high-value crops, such as flowers (Grafiadellis et al. 2000) or melons (Shaw et al. 2007), and found positive results compared with traditional production systems. A study conducted in the western Kenyan town of Eldoret, however, shows that hydroponic systems are not profitable under all circumstances (Croft 2016). The study evaluated three hydroponic systems—Kratky, NFT, and ebb and flow—growing African leafy vegetables (ALV) for profitability and nutrient concentration, with the ebb and flow system only producing seedlings for the other two hydroponic systems. The study calculated the net present value (NPV) and benefit-cost ratio for each system with a five-year time horizon. However, neither the soilbased system nor any of the hydroponic systems was profitable compared with purchasing ALV at the market. Soil-based production would become profitable only if the opportunity cost was close to zero. Among the three hydroponic systems analyzed, the NFT system was the closest to profitable, while the Kratky system consistently had the worst benefit-cost ratio and NPV values. For hydroponic systems to be profitable, vegetable prices would have to increase by 1,027 percent or input costs would have to fall below zero. However, ALV are not considered high-value crops, which may explain some of the more negative results. The hydroponic yields were also much lower than yields from soil-based systems (table 5.8), even when considering the extended growing season that hydroponic systems can offer. The hydroponic production systems become more viable and, therefore, profitable when alternative vegetable sources become costlier—as is more likely the case for high-value horticulture—or when neither arable land nor irrigation is available. Under the average conditions found in western Kenya, however, the study found that none of the hydroponic systems was profitable or competitive compared with soil-based production (table 5.9) and purchasing ALV from markets was the most costeffective alternative. Processing hydroponic crops can improve their profitability. Value-added products comprise raw produce that has been modified or enhanced to have a higher market value and a longer shelf life, such as dried fruit. For example, TABLE 5.8 Time, Harvest, and Input Costs for Three Hydroponic Systems and Comparison with Soil-Based Production Assumed value Time (days/year/m2) Harvest (g/year/m ) 2
Annual input costs (K Sh/year/m2)
Kratky
Ebb and flow
Soil
1.97
NFT 0.75
0.97
1.89
530
511
486 seedlings
865
2,044
607
1,534
0.39
Source: Croft 2016. Note: 100 Kenya shillings (K Sh) = 0.99 US$; g = grams; m2 = square meters; NFT = nutrient film technique.
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Insect and Hydroponic Farming in Africa
