Reuse of sediment as a soil conditioner in a semiarid region dominated by subsistence farming: sediment characterization at the regional scale and effects on maize crop

Abstract

PurposeThe increasing demand for fertilizers and their rising prices has led to the search for new nutrient sources, especially in rural areas where family farming predominates. In this study, we assessed the potential of reusing sediment deposited in surface reservoirs as a soil conditioner in a semiarid region, focusing on two features: the characterization of sediment physicochemical properties at the regional scale and the effect of the substrate containing sediment on the growth and physiology of maize.MethodsSediment from the beds of 14 reservoirs was investigated, and two of them were used for the preparation of substrate for maize cultivation. Differences between the physicochemical properties of the sediments were analyzed using ANOVA and Tukey’s test at a significance level of 0.05. The experimental design of the plant experiment was entirely randomized, in a factorial arrangement of two sources and four doses of sediment: 25, 50, 75, and 100% of the economic dose of 100 t ha−1 previously proposed in the study region. Two treatments were considered as controls: a substrate containing only soil and a treatment containing soil and chemical fertilizer. The data for each treatment were submitted independently considering the doses and sediment sources, and the means were compared by Tukey’s test.ResultsIn general, nutrient contents were higher in the sediment of the surface reservoirs than in the soil. For instance, the concentrations of nitrogen and potassium were three to 10 times higher in the sediment, compared to the soil, and the organic matter content was up to six times higher. In the plant experiment, the dose and source of the sediments influenced all of the analyzed variables. The addition of sediments to the soil increased the chlorophyll content, photosynthesis rate, and growth of the leaves in relation to the treatment containing only soil. There were no significant differences between the biomass production and the plants’ nutrient extraction with the largest dose of the most enriched sediment when compared to the treatment with chemical fertilizer.ConclusionsThe experiment of maize plant growth showed the feasibility of using sediment deposited in reservoirs as a soil conditioner due to the enrichment of nutrients, organic matter, and fine particles. Therefore, sediment reuse has potential to improve livelihoods and food security, as well as contributing to a circular economy. However, prior analysis is required to avoid soil contamination and to set the most appropriate sediment dose, due to the high spatial variability of the sediment characteristics.