Chemical characteristics of Amazonian Dark Earth in Santarem, Brazil

Abstract

Possible sources of incorporation of P, Ca, Mg and K into the Amazonian Dark Earth The Indian-style arrows represent the incorporation in the pre-colonial period. The main sources of P and Ca (carbonate and phosphate) are bones of fish and other animals, and carapaces of chelonians. 2+ 2+ + This research aimed at to compare some chemical characteristics (pH in water, and KCl, Ca , Mg , K , 3+ Al , organic phosphorus 'P ' and available phosphorus 'P ') of anthropogenic and non-anthropogenic org ava soils. Soil samples were collected at five depths: 0-20, 20-40, 40-60, 60-80 and 80-100 cm in two archaeological sites and one non-anthropogenic area. The analysis revealed that the anthropogenic soils presented higher amount of P than the non-anthropogenic ones, and that these amounts presented a ava 2+ positive correlation with the Ca contents, which reflects the incorporation of animal bones, mainly fish to + these soils. However, the non-homogeneous distribution of these species and the low K contents found in most samples may be limiting for some cultures. Finally, it was possible to differentiate samples of the anthropogenic soils from non-anthropogenic ones by using the values of pH in water and KCl, as well as the P and P contents. org ava

Chemical Soil Attributes in Different Use Systems, Itacoatiara-Am, Brazil

“…In a study carried out by Embrapa (2017), calcium levels (0.16 to 0.24 cmolc kg -1 ) were found to be similar between forest and pasture, however, their levels were higher in the SAFs (12,97 cmol c kg -1 ). About 100% of the total K + in the soil is in an exchangeable form, which is poorly absorbed by soil clays, thus being easily absorbed by plants and also conducive to leaching (Silva et al, 2018). For K + , there was a significant increase (p <0.01) in the concentration between the systems studied.…”