Waste from sewage treatment plants used in soybean cultivation: its influence on crop development

Abstract

The aim of the present study is to assess the effect of using composted sewage sludge (CSS) and wastewater from a sewage treatment plant (WW) on soybean plants’ development. Treatments were assessed through completely randomized design experiments carried out at split-plot arrangements based on nitrogen fertilization levels and types and on irrigation water nature – potable (WP) and wastewater (WW). Seven nitrogen fertilization levels were distributed into two plots represented by irrigation with WP and WW, namely: T0 = without nitrogen fertilization; T1 = 100% chemical nitrogen fertilization; T2 = 50% chemical nitrogen fertilization + 50% nitrogen fertilization via CSS; T3, T4, T5 and T6 corresponded to 100%, 150%, 200% and 250% CSS nitrogen fertilization, respectively. Conventional nitrogen fertilization replacement by CSS did not significantly change the behavior of the assessed variables: plant height and mass of 100 grains. This finding points towards the possibility of saving inputs by replacing chemical fertilization by organic fertilization. Irrigation with wastewater led to 37% increase in dry matter mass and 21% in mass of 100 grains.