Integrated aquaculture - floating agriculture: is it a valid strategy to raise livelihood?

摘要

Floating agriculture was an indigenous soilless system widely diffused in Meso-America and South East Asia. It was practiced for thousands of years before the advent of modern agriculture and allowed farmers to crop in flooded areas where no other land uses were possible. Plants grew on rafts made of composted water weeds, which were piled up on water bodies, by simply stripping nutrients released from decaying organic matter. In the vision of sustaining livelihoods and refining climate change strategies, floating agriculture can be adopted as a low-tech production system with almost no use of chemical fertilization. Floating rafts could improve productivity per unit of land and support water fertilization strategies in integrated agriculture aquaculture systems (IAAS), where leaching of nutrients in water improves pond primary production and sustains fish growth. Floating agriculture could also be adopted as bioremediation tool to reduce the impact of aquaculture effluents from nutrient-rich ponds. Scoping research carried out in Thailand used floating beds made of different blends of water weeds, composted manure, and rice husk ash on different aquaculture water. Results from two trials with cabbage (Brassica campestris L. 'Pekinenis') and lettuce (Lactuca sativa L. 'Bionda degli Ortolani') showed that productivity from composted manure rafts (cabbage) and nutrient-rich ponds (lettuce) was respectively similar or even higher than high input soil agriculture. A financial appraisal of the systems under study showed high profitability with very little investment costs. Results suggest that adoption of this system is possible as a strategy to increase productivity or to raise livelihood and food security among poor people wherever no access to land, credit or production inputs are available.