Forms and buffering potential of aluminum in tropical and subtropical acid soils cultivated with Pinus taeda L.

Authors: RODRIGUES, ANTONIO - Universidade Federal De Rondonia; MOTTA, ANTONIO - Federal University Of Parana Polytechnic Center; MELO, VANDER - Federal University Of Parana Polytechnic Center; GOULARTE, GABRIEL - Federal University Of Parana Polytechnic Center; Prior, Stephen - Steve

Submitted to: Journal of Soils and Sediments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2018
Publication Date: 2/17/2019
Citation: Rodrigues, A., Motta, A., Melo, V., Goularte, G., Prior, S.A. 2019. Forms and buffering potential of aluminum in tropical and subtropical acid soils cultivated with Pinus taeda L.. Journal of Soils and Sediments. 19:1355-1366. http://doi.org/10.1007/s11368-018-2144-7.
DOI: https://doi.org/10.1007/s11368-018-2144-7

Interpretive Summary: Tropical and subtropical soils with high rainfall frequency are often more acidic due to aluminum (Al) build up in soil. In southern Brazil, soils with this feature are often used for growing pine trees since they can tolerate more Al than agricultural crops. Little attention has been given to explaining changes in Al forms in upper and lower soil layers. This study compared several extraction methods used to measure Al in soil layers at several pine plantations in southern Brazil. Methods that best predicted Al accumulation within these soil layers will be discussed. This study increases our knowledge base on how Al is distributed among soil layers in these forest ecosystems.

Technical Abstract: Several interactions between Al and the solid phase of soil influence Al buffering in soil solution. This work evaluated soils cultivated with Pinus taeda L. to determine Al forms in organic and mineral horizons using various extraction methods and to relate acidity with clay mineralogy. Organic and mineral horizons of 10 soil profiles (up to 2.1 m deep) in southern Brazil were sampled. Organic horizons were separated into fresh, aged, and fermented/humified litter. Samples exhibited high Al accumulation, with higher levels at the litter base (maximum of 3.2 g kg-1). The CuCl2 method had higher Al extraction capacity than the KCl method for litter. There was an inverse relationship between degree of soil weathering and soluble and exchangeable Al in soils. Available Al increased with higher Si proportion in minerals of the clay fraction (2:1>1:1>0:1). Organic matter had less influence on Al dynamics in soils. The best predictor of Al accumulation in the youngest litter horizon was extraction of amorphous minerals with pyrophosphate and NaOH solutions. These extractors are normally used to predict the level of Al buffering in soils.