Atributos químicos e microbiológicos em Latossolo amarelo sob sistemas agroflorestais e floresta secundária em Bragança, Pará.

Abstract

The objective of this study was to evaluate the chemical and biological attributes in different depths of a Yellow Latosol, established with agroforesty arrangements involving acai (Euterpe oleraceae Mart), cupuaçu (Theobroma grandiflorum), paricá (Schizolobium amazonicum Huber) and inga (Inga edulis Martius), in areas under management using born and not born of vegetation, under influence of seasonal variation. Trough this research, we intend to determine if the SAF are presented as an alternative of use of soil, in sustainable bases. The experiment was installed in the Community of Benjamin Constant, Bragança, PA. The experimental design was completely randomized design with split plots, and the experimental area consists of 6804 m2, divided into two sub-areas of 3402 m2, being a burning subject, called an agroforestry system (SAF1) and one without burning represented by agroforestry 2 (SAF2). Were evaluated the chemical and biological attributes [exchangeable K, Ca, Mg, Al, available P, potential acidity (H + Al), pH in water, cation exchange capacity (CEC), microbial biomass carbon (CBM), organic carbon in soil (C), microbial biomass nitrogen (NBM), total nitrogen (N), organic matter (OM), the rate Cmicrobial/Corganic (CBM:C), Nmicrobial/total N (MBN:N) and basal respiration (CO2)]. Soil samples were collected in mini-trenches at the depths 0-5, 5-10 and 10-20 cm at each site corresponding to the systems in use, in February (rainy season) and October (dry season) 2008. During the rainy season (February), the values obtained for the studied variable, in general way, with except for exchangeable Al and pH in relation to the less rainy season. The exchangeable Al increased with depth when the soil was collected in the less rainy season. The MBC and basal respiration were efficient in detecting changes in field soil organisms. The agroforestry system without burning was as efficient as the secondary forest in nutrient cycling and input of organic matter and is recommended as an alternative land use on a sustainable basis.