Mangrove rice productivity and pedogenic trends in Guinea Bissau, West Africa

Purpose: West African mangrove ecosystem provides a large array of ecosystem services. In the last few decades, rice production, obtained after clearing of the natural vegetation, led to a shrinking of mangrove coastal swamps, while large areas of rice fields quickly became unproductive and were abandoned. An optimization of land use according to the soil suitability is thus necessary. In order to characterize the edaphic properties associated with rice productivity decline with time, we studied soil properties along chronosequences, from untouched mangrove swamps to abandoned fields. Methods: We sampled soil profiles and topsoils in some sites in mangrove swamps and mangrove paddy fields in Guinea Bissau; we analysed the main chemical, physical and edaphic properties; we analysed clay mineralogy as well. Results and conclusions: The results show that only sulphate acidification evidence was correlated with rice production decline. Topsoil nutrient contents and salinity were completely uncorrelated.