The field was divided into three treatments (split-plot) in which three different regimes were applied: (i) Burnt

sugarcane – Before harvest, the sugarcane crop was burnt to remove the leaves. The stem was then manually harvested. After harvest, the soil remained ATM Kinase Inhibitor uncovered.   (ii) Green sugarcane – Harvest was performed using a machine that separates the sugarcane leaves from the stems. The leaves are then returned to the soil. After harvest, the soil remained covered by the vegetal residues.   (iii) Control – covered with trees interspersed with open areas, contiguous to the sugarcane treatments.   The sugarcane treatments had 6 years of implementation until the sampling. The fertilization regime of the area was composed by the addition of 400 kg ha-1 of NPK (5-25-15) during the implementation of the sugarcane crop (6 years before the

sampling), and an annual addition of 400Kg of NPK (20-0-20), after each harvest (8 months before the sampling). Monoammonium phosphate selleck chemicals llc was used as nitrogen source during the first fertilization and urea in all other subsequent ones. To allow replication, per treatment, five 5x5m subplots were defined randomly (approximately 10 m of distance from each other). The soil was collected as five replicates per subplot (which were pooled) approximately to 10 cm depth, using a core borer (total up to 2.5 kg). The sizes of the burnt sugarcane, green sugarcane and control treatments were 23.5, 9.9 and 2.9 ha, respectively. The native vegetation was chosen as control because it represents the soil’s natural condition; it received no addition of fertilizers. This control was a small fragment of native Cerrado (Cerradão-type, characterized by a dense formation of trees buy Cobimetinib up to 4 meters tall) [4]. The three treatments were very close to one another, less than 300 m apart. Soil physical and chemical properties Subsamples of soils from each site were air dried, sieved (2 mm)

and analyzed chemically. Exchangeable nutrients: Ca2+, Mg2+ and Al3+ extracted by 1 M KCl; P, Na and K by Mehlich-1 extractant – 0.05 mol L-1 in HCl in 0,0125 mol L-1 H2SO4) and pH (soil:water, 1:10); Potential acidity: H + Al extracted with calcium acetate 1 N (pH 7), titrated with 0.0125 N NaOH, were analysed according to Embrapa [27]. Inductively coupled plasma apparatus for Ca2+, Mg2+ and Al3+, flame emission (K and Na) and photocolometry (for P) were used for nutrient determinations. All analyses, except bulk soil density and potential denitrification (where samples were pooled), were conducted with all five replicate samples per treatment. Soil granulometry was determined using the aerometer method, after chemical dispersion [27]. Soil bulk density (2.5-7.5 cm) was determined in undisturbed samples, collected with 5 cm diameter and 5 cm height stainless steel rings, from three samples per treatment.