Circular Economy Through the Effect of Biosolids on Arrowroot (Maranta arundinacea) Rhizome Production: Physicochemical Analysis of Soil and Initial Crop Development

Abstract

Sewage Sludge (SS) can improve the agricultural condition of tropical soils, which are generally acidic and deficient in nutrients and organic matter, thereby promoting better crop development as a positive outcome. The objective of this study was to apply different doses of SS to a tropical soil cultivated with arrowroot and to analyze the physicochemical changes in the soil using Tukey’s test and Principal Component Analysis (PCA), as well as to evaluate the initial crop development over a three-month cultivation period. For comparison, arrowroot was also grown in natural soil conditions and with chemical fertilizer.

Treatments with SS doses (50%, 100%, 200% and 400%) significantly improved soil physicochemical fertility parameters, including pH, P, K, Ca, Mg, S and Organic Matter (OM), compared to the control and chemical fertilizer treatments. The treatments with SS doses of 4.6, 9.2 and 18.4 t ha⁻¹ did not show significant differences in initial plant height, number and weight of arrowroot rhizomes. However, they performed better than the control, chemical fertilizer and 36.4 t ha⁻¹ treatments, with statistically significant differences observed.

Therefore, the study recommends that SS application should not exceed 18.4 t ha⁻¹ in tropical soils for the cultivation of arrowroot (Maranta arundinacea). PCA showed that S, P, Ca and Electrical Conductivity (EC) undergo substantial changes in their concentrations when SS is applied to the soil. From an agricultural perspective, the study demonstrates that cleaner production in tropical soils is feasible within the framework of a circular economy in Wastewater Treatment Plants (WWTPs), which can reduce the disposal of SS in landfills by considering it as an agricultural product, thereby promoting sustainable development.