Testing the Feasibility of Usumacinta River Sediments as a Renewable Resource for Landscaping and Agronomy

Abstract

Fluvial sediment recycling in agronomy is a relatively recent development, as sediment fertilizing potential for crops is unexplored. Freshwater sediments can act as fertilizer and improve the aeration of soils to increase the yield of crops, support vegetation for landscaping, and provide protective cover against erosion. This study focuses on the investigation of the agronomic potential of Usumacinta River sediments. The pH of the sediments is around 8.5, which is slightly alkaline. The organic matter content is low (5.7%). The sodium absorption ratio is 1.2 and the electrical conductivity is low (0.02 mS/cm). These values indicate that sediments are nonsaline, which is essential for the growth of crops and vegetation. The environmental characteristics of sediments show that the heavy metals, polycyclic aromatic hydrocarbon (PAH), and polychlorinated biphenyl (PCB) pollutants in sediments are below the recommended thresholds. In addition, sediments from the Usumacinta River contain minerals such as potassium and iron oxides that are helpful in improving the biological and nutritional characteristics of the soil. Furthermore, the pH, granulometry, mineralogy, organic matter, and carbonate contents of the Usumacinta River sediments are similar to agronomic soils. The Usumacinta River sediment’s potential for agronomy was practically investigated by sowing ryegrass (Lolium perenne) in a greenhouse by using the local climatic conditions and mixing sediments with potting soil. Three soil compositions were used to evaluate the germination and growth of ryegrass. The soil compositions were 100% potting soil (C1), 50% sediments + 50% potting soil (C2), and 100% sediments (C3). The growth rate of ryegrass was evaluated by monitoring the increase in grass height and production of fresh biomass. The germination of ryegrass was similar in all three compositions. The growth of ryegrass and production of fresh biomass were the most significant with 100% potting soil (0.25 kg/m2), somewhat less with sediment mix (0.18 kg·m2), and were the least significant with 100% sediments (0.05 kg/m2). The mixture of potting soil and sediments shows similar growth to 100% potting soil. The ryegrass seed germination, growth, and production of fresh biomass with the mixture of sediments gave encouraging results, and underlined the potential of sediments for soil amendments for agronomy and protective developments, such as limiting riverbank erosion, gardening, and landscaping.