DATOS PARA EL DESARROLLO DE UNA RED INTEGRADA DE SEGUIMIENTO DE LA CALIDAD DE SUELOS EN GALICIA (N.O. DE ESPAÑA): BALANCES GEOQUÍMICOS EN SUELOS FORESTALES (PINUS RADIATA). 2.SALIDAS DE ELEMENTOS Y BALANCE DEL SUELO FORESTAL.

M. X. GÓMEZ-REY, R. CALVO DE ANTA

Dpto. de Edafoloxía e Química Agrícola. Facultade de Bioloxía. Universidade de Santiago de Compostela, 15782. Santiago de Compostela.

Abstract

The present study is a continuation of work presented in a previous paper, analysing the element losses from forest soils in the form of drainage and biomass extraction, in order to estimate the input-output balance during the years 1997 and 1998. The study is carried out in Pinus radiata forest located in area with minimum human influence in Galicia (NW Spain). Soils showed an a global positive balance for S, K and P (about 14, 14 and 0,7 kg ha-1 year-1, respectively). The annual rate of relative increase was, S: 0,03 %;P: 0,008 %; and K: 0,004 %. In contrast, the global balance was negative in the case of Na, Ca, Mg, Si, Fe and Al (-10, -4, -0.8, -29, -4 and -1 kg ha-1 year-1, respectively). The order of relative mobility was: Ca>Na>>MgÅSiÅFe>>Al (0,054 %, 0,038 %, 0.002 %, 0,002 %, 0.002%, and 0,0001%, respectively.
The obtained results show the importance of the role exerted by the vegetation in the minimization of the element losses by washing, through the biogeochemical cycles, distinguishing strong differences between superficial horizons (generally with partially positive balances), and the rest of the soil.

Key Words: Biogeochemical budgets, forest soils