Macro e micronutrientes na serapilheira depositada em solos submetidos a usos distintos no semiárido

Abstract

Eucalyptus reforestation is a conservation practice whose benefits to soil fertility and nutrient cycling have been observed under different edaphoclimatic conditions, restoring physical, chemical, and biological attributes affected by degradation. However, it is limited in the Brazilian semi-arid region by water deficit and the intensification of erosion and desertification, raising questions about the effectiveness of litterfall in the recovery of sandy soils. This study tested the hypothesis that eucalyptus reforestation generates litterfall richer in macro and micronutrients than degraded pasture areas and comparable to that observed in preserved native forest. The objective was to quantify biomass and macro and micronutrients (Ca, Mg, K, P, Na, Cu, Fe, Mn, Zn) in the litterfall of eucalyptus plantations compared to degraded pasture and native forest in Acaraú-CE. The experiment took place in Acaraú-CE, with a completely randomized design, three treatments (native forest – MN, eucalyptus – EUCA and degraded area – AD) and 16 repetitions, totaling 48 litter samples collected using 0.25 m² collectors. The samples were dried at 60°C to obtain the estimated dry biomass in hectares, incinerated in a muffle furnace (450-550°C) and analyzed by atomic absorption spectrometry, flame photometry and spectrophotometry for nutrient quantification (Ca, Mg, K, P, Na, Cu, Fe, Mn, Zn). After a normality test, an analysis of variance (ANOVA) was performed, revealing significant differences (p<0.01) between land uses, with MN showing the highest biomass (2.8 t ha⁻¹), followed by EUCA (2.4 t ha⁻¹) and AD (0.8 t ha⁻¹). Nutrient inputs followed the order MN > EUCA > AD for all nutrients, with Ca (18.69 kg ha⁻¹ in MN), Fe (292.87 kg ha⁻¹ in MN), and Mn (507.37 kg ha⁻¹ in MN) being the most significant. It was found that the type of vegetation cover significantly influences litter production and nutrient accumulation, with significant differences between MN, EUCA, and AD. Nutrient input in EUCA was higher than in AD, but lower than in MN, highlighting the importance of reforestation and preservation of native forest in the semi-arid region.