Biochar de lodo de esgoto : tempo e temperatura de pirólise na performance agronômica da rúcula (Eruca vesicaria (L.) CAV.)

Abstract

Biochar has been considered a sustainable option for the agricultural use of sewage sludge (SS). However, gaps still exist regarding the nutritional impacts of biochar on short-cycle crops. Therefore, this study investigates the effect of biochar derived from sewage sludge, produced under different pyrolysis conditions, on the agronomic performance of arugula (ERUCA vesicaria (L.) CAV.). Raw sewage sludge (SS) was processed in a batch pyrolysis reactor at two temperatures (400°C and 500°C) and two residence times (1 hour and 2 hours), with an average heating rate of 4.5°C min-1. A greenhouse experiment was conducted using a completely randomized design with 10 treatments and four replications. The treatments consisted of the following biochar doses: 20 and 30 Mg.ha-1 for each type of biochar obtained (according to the processing parameters). These amounts of biochar were incorporated into 1 kg of soil in containers with a capacity of 1 dm³, along with the minimum recommended NPK fertilization dose for the crop (N – 100 kg/ha; P – 40 kg/ha; K – 90 kg/ha). Additionally, a standard treatment using Carolina Soil was employed to establish comparison parameters among the different treatments evaluated. Soil chemical properties were assessed before and after the cultivation of arugula. Agronomic development of the crop was evaluated through variables such as the number of leaves, plant height, fresh and dry mass of the aerial part, as well as nutrient concentrations. The results showed that the addition of biochar to the soil, regardless of pyrolysis time and temperature, significantly increased phosphorus levels and improved organic matter content. Although the addition of sewage sludge biochar made the 8 soil more acidic, arugula demonstrated tolerance to the lower pH and exhibited adequate growth.