Effects of agricultural practices on properties and metal content in urban garden soils in a tropical metropolitan area

Abstract

The appearance of agriculture in urban areas improved the healthy diet of people by the consumption of fresh vegetables and fruits. This study assessed the level of fertility, the impact of cropping system and of exploitation time on physicochemical properties and pseudo-total and EDTA-extractable metals contents of urban garden of vegetable soils in Libreville (Gabon). The results indicated a low fertility of cultivated soils. The metal contents in soils were generally different between culture in open field and culture under shelters. Except Al which could be toxic for cultivated vegetables, the soil properties and metal element concentrations decreased significantly in open field soil with time, while they did not vary in open shade structure soils. The pseudo-total cadmium concentration was below detection limits in all soils. The multivariate analysis showed that Al, Fe and Pb were of lithogenic origin, and Cu, Zn and Mn were of anthropogenic origin.

Keywords

• soil fertility
• metal mobility
• multivariate statistical analysis
• Libreville