Is vegetable cultivation under low tunnels a profitable alternative to pesticide use? The case of cabbage cultivation in northern Tanzania

摘要

The health benefits of fruit and vegetable consumption can be jeopardized by pesticide residues, especially in developing countries, due to their misuse. While vegetable growing under cover is growing in popularity worldwide as an effective technique for improving yields while reducing pesticide use, these protected cultivation techniques often remain underutilized by smallholder farmers. A cost-benefit analysis was conducted with fifty smallholder farmers in northern Tanzania over two seasons to compare the profitability of growing cabbage in open plots and under inexpensive low tunnels. Although all farmers significantly improved their yields under nets over the two seasons (9.85, as opposed to 6.80 kg m(-2) and 10.09, as opposed to 8.63 kg m(-2), in each season respectively) and reduced their pesticide use (by 3.5 and 2.8 times), the large variations in market prices observed between seasons called into question the profitability of this cultivation technique. With the conducive market conditions of the second season, it would have taken 5.3 crops cycle on average, i.e. less than 2 years, to recoup the investment costs of low tunnels, whereas with the poor market conditions observed in the first season, the investment in tunnels compounded the negative economic results obtained from growing cabbages in an open field. Consequently, our results showed that using low tunnels could be a suitable alternative for reducing pesticide use, but this technique was not economically viable with the existing marketing systems used by the farmers. For this technique to be adopted, further work is needed to identify changes in vegetable marketing systems that would promote the use of cultivation techniques that reduce pesticide use.