Partition of root water extraction between soil layers with distinct hydraulic properties / Partição da extração da água do solo por plantas entre camadas com propriedades hidráulicas distintas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Root water extraction is determined by soil hydraulic conductivity and water potential gradients, both dependent on soil water content. In this dissertation the experimental test of a root water extraction and partition model is described for a plant whose root system is divided over soil layers with distinct hydraulic properties. An experiment was conducted in a greenhouse with Sorghum (Sorghum bicolor (L.) Moench) plants growing in split-pot lysimeters containing two physically divided compartments. Four of these lysimenters were built, filled with material from two soils with different texture (a médium textured soil - AR and a clayey soil - AG). During a month and a half a water regime was applied alternating the irrigation among the compartments. The soil water content in the compartments was measured with TDR and tensiometer equipment. Soil hydraulic properties retention and conductivity were analyzed by standard methods. Root density was determined by weighing at the end of the experiment, resulting in values twice as high in soil AR compared to soil AG. It could be observed that water extraction occurred preferentially from the lysimeter compartments with the highest matric flux potential. At certain occasions, water transfer from the compartment with higher matric flux potential to the lower one was observed, transferring water from root to soil (hydraulic lift). Referring to the model, in order to compensate for root distribution heterogeneity, root activity and soil-root contact, an empirical factor f was added to the model. Its value was determined by a numerical fitting procedure aiming the highest correlation between model and observation in the four lysimeters. For soils AR and AG, the values of f determined were 0.01506 and 0.003713, respectively. The tested model described the observations reasonably well using these values of f.

ASSUNTO(S)

root system. Água do solo - extração - modelagem soil water extraction - modeling sistema radicular i. condutividade hidraúlica do solo soil hydraulic conductivity

ACESSO AO ARTIGO

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