Tropical soils degraded by slash-and-burn cultivation can be recultivated when amended with ashes and compost
This article (PDF) in the journal Ecology and Evolution tests a selective slash-and-burn agriculture (some trees are intentionally not cut), coupled with compost amendment in the dry region of Madagascar. Slash-and-burn agriculture is considered as a driver of deforestation; the forest is converted into agricultural land by cutting and burning trees and the fields are abandoned after few years because of yield decrease and weed invasion. Therefore, the authors propose a reclamation strategy for abandoned fields allowing and sustaining re-cultivation. Corn plants were grown on four types of soil amendments: no amendment (control), compost, ashes, and compost + ashes additions. The amendment compost + ashes strongly increased corn yield, 4-5 times compared to ashes or compost alone. On control plots, yield was negligible as expected on these degraded soils. Results show that compost and ashes were complementary fertilizing pathways promoting soil fertility through positive effects on soil moisture, pH, organic matter, and microbial activity. To conclude, the results provide evidence on the potential of recultivating tropical degraded soils with compost and ashes. This would help mitigating deforestation of the primary forest by increasing lifespan of agricultural lands. The proposed solution is original because it considers the deeply socially rooted slash-and-burn practice as an acceptable solution if it is well matched with soil organic matter enrichment, whereas it is usually dismissed as destructive. Recognizing this type of agriculture as a cultural heritage and trying to modify it to make it sustainable paves the way toward a more integrative vision of traditional agriculture along with tropical forest management.