Indirect use value of improved soil health as natural capital that supports essential ecosystem services: A case study of cacao agroforestry

Multifunctional landscapes, such as agroforestry, that improve soil health are essential in sustaining terrestrial life by supporting various ecosystem services (ESs). However, decision-making often requires more attention to soil health because its parameters have no market value. In this study, we aim to evaluate soil health parameters in cacao agroforestry and monoculture and their degradation due to erosion and to estimate their indirect use value (IUV). We develop a soil health economic valuation approach bridged by ESs because the economic valuation of ESs tends to be better studied. We estimated the IUVs of the eight soil health parameters by using the direct proxy revealed prevalence valuation method on the basis of the valuation of the four ESs they support: water regulation, climate regulation, nutrient retention and biodiversity. The total IUVs for cacao agroforestry were USD 633 with Endoaquepts and USD 723 with Dystrudepts and for cacao monoculture were USD 415 with Endoaquepts and USD 575 with Dystrudepts. Soil carbon has the highest contribution to IUV, followed by soil nitrogen. Agroforestry not only increases IUV but also minimises its decrease due to erosion. Despite economic valuations being subject to uncertainty, these results encourage the internalisation of soil health values in sustainable land management design.