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Effects of potassium fertilization and throughfall exclusion on the hydraulic redistribution of soil water in Eucalyptus grandis plantations

Asensio V., Laclau J.P., Domec J.C., Jordan-Meille L., Bouillet J.P., Nouvellon Y., Abreu-Junior C.H.. 2015. Natal : Sociedade Brasileiro de ciência do solo, 1 p.. Congresso Brasileiro de ciência do solo. 35, 2015-08-02/2015-08-07, Natal (Brésil).

The transport of water from moist soil layers to dry through the roots of some species is an important process for plant survival during long dry periods. The objective of the present study was to evaluate if Eucalyptus grandis roots growing in a tropical region characterized by long dry periods passively move water from deep to shallow soil layers, which is known as ¿hydraulic redistribution¿. The experiment was carried out at the Itatinga experimental station (SP, Brazil) that included four contrasting experimental plots resulting from the combination of two set of treatments: with/without potassium fertilization (+K/-K, respectively) and with/without throughfall exclusion (+W/-W, respectively). Sap flow was measured in superficial Eucalyptus coarse roots from the end of the 2014 dry season to the end of the 2015 rainy. We detected reverse sap flow (water in superficial roots going to the soil surface far from the trunks) all of the months, even during the rainy season, and in all the treatments, except in -K-W, where reverse flow started two months after the beginning of the rains (January). The lowest flow densities in superficial roots were observed in -K and/or -W, but reverse flow occurred in more roots or during more days per month than in treatments +K and +W.

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