TABLE 4.9 BSFL, Meal, and Frass Production from Maize Output Substrates, Zimbabwe Waste/loss Total component waste/loss (tons)
BSFL (tons)
BSFL meal (tons)
High
Low
High
Low
Frass (tons) High
Stover
656,776
197,033
65,678
66,991
Postharvest losses
114,751
34,425
11,475
11,705
3,902
34,425
11,475
Process waste 29,602
8,881
2,960
3,019
1,006
8,881
2,960
3,238
971
324
330
110
971
324
804,367
241,310
80,437
82,045
27,348 241,310
80,437
Consumption waste TOTAL
22,330 197,033
Low 65,678
Source: Original table for this publication. Note: BSFL = black soldier fly larvae; high = 30 percent conversion; low = 10 percent conversion.
5. Additional waste quantities, such as distribution wastes and consumption wastes, are less abundant in the supply chain, more difficult to recover, or not quantifiable. Distribution waste includes losses at wholesale markets, supermarkets, retailers, and wet markets. These wastes amount to 2 percent of the available processed maize meal (FAO 2011) and are not recovered; hence, they are not included in the maize analysis. Consumption waste includes losses and wastes at the household level and amount to only 1 percent for pulses, oil seeds, and cereals including maize meal in SubSaharan Africa (FAO 2011). In this case, consumption waste for maize meal is less than 3 kg/ha. However, consumption waste was included in the maize analysis because it is quantifiable and recoverable, although its amount is not significant compared with other waste sources. Sugarcane Figure 4.11 shows the food supply chain and associated waste stream for sugarcane in Zimbabwe. The following analysis determines BSFL meal and frass production based on the five-year averages, from 2013 to 2017, for total annual sugarcane production (3,619,823 tons) and harvested area (43,890 ha). The numbered bullets below show the kilogram per hectare calculations for each type of sugarcane-associated waste. These are then multiplied by the total area under cultivation (hectares) and divided by 1,000 (kg/ton) to determine the total tons per hectare per waste type. Table 4.10 summarizes the total sugarcane-derived wastes recoverable and suitable as substrates for BSF breeding. Table 4.11 applies the 10 and 30 percent conversion rates to the wastes in table 4.10 to calculate the rate of converting sugarcane wastes to BSFL meal and frass. Mainstreaming Insect Farming
149
