Agroforestry shows higher potential than reforestation for soil restoration after slash-and-burn: a case study from Bangladesh

Abstract

Increasing land demands for food production has led to large-scale soil degradation in the hilly regions of south-eastern Bangladesh. An intensification of slash-and-burn techniques, where fallow intervals have shortened considerably in recent years, has led to widespread losses in soil quality. Here we sought to test to what extent do current agroforestry practices in the area, compared with current reforestation efforts, can ameliorate different physicochemical soil properties after the abandonment of slash-and-burn practices. We observed that concentrations of soil organic matter (4.75%), available phosphorous (12.17 μg g−1) and exchangeable potassium (0.39 mg kg−1) in agroforestry plots were significantly higher than in reforestation (3.18%, 6.50 μg g−1 and 0.21 mg kg−1, respectively) or slash-and-burn plots (1.83%, 5.90 μg g−1 and 0.03 mg kg−1, respectively). While reforestation and agroforestry may both serve to restore soil functions but we observed higher benefits in the latter system. Thus, agroforestry systems may be a suitable land management system for replacing ancestral slash and burn techniques but care should be taken to diminish soil compaction.