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The açaí palm (Euterpe oleracea Mart) is native to the floodplains of central and South America and is cultivated in Brazil for its berries, which are considered to be a 'superfood'. The waste açaí fiber and seeds obtained after fruit processing pose a challenge since they remain unutilised despite being an abundant waste by-product of açaí processing.This leads to a build-up of waste, regular dumping and environmental management challenges. Here we examine the potential use of açaí seed biochar as a soil conditioner. The biochar was produced from waste seeds in a handmade kiln, incorporated into two soils of different textures and then compacted in volumetric rings with a hydraulic press. The samples were kept in a greenhouse for a 270-day incubation period. After this, the samples were evaluated for their soil physical and chemical attributes. Nine months after the application of the açaí seed biochar, soil physical properties were not affected, except for the soil aggregate size distribution, for which the highest dosage resulted in a larger weighted average diameter. However, biochar increased phosphorus, potassium and magnesium contents, and reduced the aluminum content, which was reflected in an increase of the base saturation and a reduction in aluminum saturation. Therefore, within a relatively short time period, the biochar was found to improve soil chemical quality more so than soil physical properties, thus offering potential as a sustainable solution to manage açaí waste in the Amazon region.

Leucaena leucocephala is an arboreal legume with many applications in agriculture (forage, wood production, charcoal, soil improvement, shading, windbreak, and hedge). Its seeds show dormancy, which is caused by physical blockade through resistant and impermeable integument. The aims of this study were to evaluate and determine efficient methods for overcoming dormancy in Leucaena leucocephala seeds. The experiment was carried out in Tangará da Serra city, Brazil, adopting a completely randomized design, with four replications. The treatments consisted of no scarification (T 0), scarification with sandpaper (T 1), immersion in concentrated H 2 SO 4 for 5 min (T 2), 10' (T 3), 15' (T 4), and 20' (T 5), and immersion in water at 80°C for 5' (T 6), 10' (T 7), 15' (T 8) and 20' (T 9). The seeds were placed in germination chamber at a temperature of 25ºC and photoperiod of 12 hours day/night over a period of 10 days, for all treatments, using 50 seeds per replicate. The experimental data were submitted to analysis of variance (type I error) by F test (p<0.05) with comparison of averages performed by Tukey test (p<0.05). The treatment that showed best efficiency in overcoming seed dormancy was immersion in concentrated H 2 SO 4 (density of 1.84 and purity of 95%) for 20 min, with 93.0% of viable seed germinated. Immersion of seeds in water at 80ºC for 20 min (0.0% seed germination) showed lowest efficiency in overcoming dormancy of Leucaena leucocephala seeds. It was concluded that treatment with immersion in concentrated H 2 SO 4 for 20 min is the most efficient in overcoming dormancy of Leucaena leucocephala seeds, showing higher values of first germination count, germination percentage, germination speed index and average time of germination.

The different tillage systems interfere with soil chemical attributes mainly due to the site of preparation techniques. The aim of this study was to determine, in two time evaluation periods, the changes in soil chemical attributes affected by three tillage systems in Yellow Oxissol. The experimental design consists of a randomized block design, with split-plot (Soil Tillage systems X Depths samples) with 3 repetitions in two evaluation periods (2009 and 2012). The treatments consisted of three tillage systems, being Conventional Tillage (CT); No-Tillage (NT) and Reforestation with Paricá (RP). The two depths sampled were 0-0.1 m and 0.2-0.3 m. The attributes were evaluated as pH, organic matter, macronutrients levels, exchangeable acidity and micronutrient level. The soil tillage systems significantly affected the soil chemical attributes. In the NT system, the chemical attributes Ca, Mg, MO, P, K, Mn and Zn are concentrated on the most superficial layer of the soil, whereas in the CT there is a distribution of these variables along the topsoil.