Ação do biocarvão de resíduos de bambu como condicionador de solo e na produtividade de plantas de jambu (Acmella oleracea L.).

Abstract

This study aimed to evaluate the effect of bamboo residue biochar as a soil conditioner, analyzing its impact on the productivity of jambu plants subjected to different doses of biochar with and without liming. The experiment was conducted in a greenhouse, located in the experimental area of the Federal Rural University of the Amazon (UFRA), in Belém-PA, using a completely randomized design (CRD), adopting a 3×2 factorial scheme, totaling six treatments. The factors evaluated were three doses of biochar (0, 20 and 40 g kg⁻¹ of soil) and two liming conditions (absence and presence). Thus, the treatments were composed of: control (without liming and without biochar), liming without biochar, and combinations of the two doses of biochar (20 and 40 g kg⁻¹) with and without liming. The experiment had five replicates per treatment, totaling 30 experimental units of jambu seedlings. Soil pH, chlorophyll content (a, b and total) and biometric and biomass parameters were analyzed to quantify plant height, stem diameter, number of leaves, dry and fresh mass of leaves, stems, roots, shoots and total. Data were subjected to analysis of variance using the F test, and when significant, Tukey's test was applied to compare treatment means at a 5% probability level and the collected data were analyzed in the AgroEstat statistical program. The results show that biochar application increased soil pH, especially at doses of 20 and 40 g kg⁻¹. Liming promoted significant increases in photosynthetic pigments compared to the treatment without liming, due to the improvement in the absorption of nutrients essential for photosynthesis. Regarding plant growth, liming treatment at doses of 0 and 20 g kg-1 of biochar increased height, stem diameter and number of leaves. The addition of 40 g kg⁻¹ biochar reduced plant height but increased stem diameter, indicating a possible improvement in soil conditions. Liming also had a positive impact on biomass, while the 40 g kg-1 dose of biochar negatively affected this parameter, suggesting that its excessive application may be harmful. Therefore, the combination of 20 g kg⁻¹ with liming resulted in the best growth and biomass performances of jambu plants, being recommended as a soil additive and conditioner, in addition to helping in the possible reduction of this corrective. On the other hand, the 40 g kg⁻¹ dose is not recommended due to the unsatisfactory performance of jambu plants.