Concentration of chemical elements in dry mass of Pontederia crassipes Mart. for use as organic fertilizer in small-scale crops

Abstract

Background: the increasing demand and production costs of inorganic fertilizers motivate researchers to explore new ways to obtain organic fertilizers. Pontederia crassipes Mart., is an invasive aquatic plant that grows in a freshwater lagoon (La Turbina), in Ciego de Ávila, Cuba. It is extracted from the water and deposited on the shores of the lagoon, affecting the aesthetic value of the site. Objective: to determine the concentration of chemical elements in the dry mass of P. crassipes (in its floating and emerging growth condition), to recommend its possible use as organic fertilizer or mixed substrate in small area crops. Method: for the analysis of most of the chemical elements, both in the lagoon water and in the dry mass of P. crassipes, inductively coupled plasma optical emission spectrometry was used. Results: the water of a lagoon was characterized by high concentration of Ca. In the dry mass of P. crassipes (floating and emergent), Ca, N, and K had the highest concentrations (mg g-1), followed by Na and Al. Heavy metals had concentrations below the maximum permissible limits for organic fertilizers and substratum of the crop. The eight chemical elements quantified in the lagoon water (Ca, Cu, K, Mg, Na, P, S, and Zn) showed bioconcentration in P. crassipes (floating). Seven chemical elements showed translocation in P. crassipes (B, Ca, K, N, Na, and Sr). Conclusions: The dry mass of P. crassipes can be used as organic fertilizer or as a mixed substrate for small-scale crops. Floating P. crassipes can phytostabilize and phytoextract chemical elements in the La Turbina artificial freshwater lagoon.