Impact of Agroforestry Practice on Soil Conservation- Initial Assessment in Northwest Vietnam ^†

In the Northwest Vietnam, traditional maize (Zea mays) cultivation practices of farmers mainly based on sole cropping, intensive tillage combined with burning crop residues on steep slopes. These cultivation practices resulted in severe erosion, soil degradation, reducing crop production and un-sustainable production systems. It requires assessing of the impact of agroforestry practice on the soil conservation in the context of the upland areas in Northwest Vietnam. This study has been carried out since 2017 to present the actual impact of agroforestry practice including longan (Dimocarpus longan)+mango (Mangifera indica L.)+maize+forage grass strips (Guinea-Panicum maximum) on soil conservation. The assessment based on quantifying soil loss by soil traps and evaluating terrace’s formation by erosion pins placing above forage grass strips. The sole maize system had been using for the comparison. The initial results showed that the evaluated agroforestry practice reduced soil loss from 18.3 to 37.4% in compared with the sole maize system in 2017 and 2018, respectively. In the second year (2018), the deposition of sediment on the front and rear pins at the above grass trips was 0.81 and 0.41 cm, respectively. It indicated the increment in soil surface at the above grass strips. In contrast, the negative value of the deposition of sediment was recorded in the sole maize system. We are continuing to monitor the impact of agroforestry practices on reducing soil loss and terrace formation, and evaluate the function of the system on soil fertility improvement, nutrient use efficiency and economic profitability.