Soil Organic Matter Management: The Roles of Residue Quality in C Sequestration and N Supply - Sustainable Management of Soil Organic Matter - page 182

B.Glaseret al. SOMin Archaeological Soils

3.11

Persistence of Soil Organic
Matter in Archaeological
Soils (Terra Preta) of the
Brazilian Amazon Region

B. G LASER , G. G UGGENBERGER , L. H AUMAIER AND
W. Z ECH

Institute of Soil Science and Soil Geography, University of
Bayreuth, D-95440 Bayreuth, Germany

Introduction

Within the Oxisol and Ultisol landscape of the Brazilian Amazon region,
patches of very fertile and stable anthropogenic soils, known as Terra Preta
soils, occur. These soils are characterized by a large and stable soil organic
matter (SOM) pool and by high stocks of nutrients such as N, P and Ca
(Sombroek, 1966; Zech et al ., 1990; Sombroek et al ., 1993). Terra Preta
soils are favoured by the local farmers because they enable high crop yields.
The establishment of stable SOM seems to be decisive for the sustainable
soil fertility (Duxbury et al ., 1989; Zech et al ., 1990). Frequent charcoal
findings (Sombroek, 1966; Saldarriaga and West, 1986) provided evidence
that black carbon may be responsible for the SOM stability in these soils
as it is known that this carbon species can survive in the environment over
centuries (Goldberg, 1985). For this reason, the main objective of the
current work was to verify to what extent black carbon contributes to SOM
of Terra Preta soils. Furthermore organomineral stabilization of SOM
was investigated by particle size and density fractionation, and scanning
electron microsopy (SEM) and energy-dispersive X-ray spectroscopy

(EDX) on the separates.

Materials and Methods

The investigation area is located in the Brazilian Amazon basin. Mean
annual temperature is ~27 C and mean annual precipitation is 2050 mm at

Santarém and a bit higher at Manaus. At Santarém, 90% of the rain falls in

°