Impact of contrasting land-use on soil biodiversity and soil chemical properties in recently cleared forest soils of north-west Cambodia

Context Rapid agrarian changes in north-west Cambodia have led to extensive deforestation for upland crop cultivation. Aims This study assessed the impact of four land-use types on soil chemical and biological properties and indicators of soil health. Methods The four land uses were fallow (16 years since forest conversion), maize–cassava (14 years), mango (16 years), and mango–cassava intercropping (15 years). Soil organic carbon (C) and nitrogen (N) stocks, chemical properties, and macro-/meso-fauna were measured at four depths. Soil health indicators were assessed at 0–10 cm: permanganate oxidisable carbon (POXC), aggregation, water infiltration, and visual evaluation of soil structure. Key results Agricultural lands showed lower topsoil C than fallow, with mango–cassava intercropping exhibiting a C depletion rate of −1.42 Mg C ha−1 y−1. Significant N depletion occurred under maize–cassava and mango–cassava (−250 and −260 kg N ha−1 y−1, respectively). Maize–cassava had a higher C/N ratio due to lower N concentrations. Water aggregate stability and POXC were significantly lower under mango–cassava and maize–cassava. Soil fauna abundance and richness were reduced in agricultural lands. Conclusions The forest conversion to agriculture negatively impacted topsoil C (38% loss), labile C (35–70% loss), soil aggregation, and soil fauna. Implications These findings highlight the need to evaluate the costs of soil fertility depletion and explore and promote alternative management practices such as conservation agriculture and agroforestry, alongside financial mechanisms for soil restoration.