Time domain reflectometry in the determination of soil water content

Revista Brasileira de Engenharia Agrícola e Ambiental

Ramos, Márcio M.²  Mantovani, Everardo C.²  Martins, José H.²  Pereira, Sidney¹  Oliveira Filho, Delly² 

[1] Universidade Federal de Uberlândia, Uberlândia;UFV, Viçosa

关键词: TDR;    probe;    irrigation and automation    INTRODUÇÃO Com a crise de fornecimento de energia elétrica por que atravessou o País;    racionamento de energia de 2001;    o uso deste recurso e da água destinada à irrigação se torna cada vez mais restritivo e oneroso;    implicando em prioridade para sua otimização em seus diferentes usos;    tanto no contexto estratégico de reservas energéticas quanto sob o ponto de vista ecológico;   

DOI  :  10.1590/S1415-43662006000200009

学科分类：农业科学（综合）

来源: Universidade Federal de Campina Grande * Centro de Ciencias e Tecnologia

【 摘 要 】

This study had as objective the determination of the correlation between the apparent dielectric constant and water content for a clay-textured soil and a sandy-textured soil by fitting a cubic polynomial type model. To measure the soil water content a TDR system was proposed, which consists of: oscilloscope; electromagnetic pulse generator; coaxial cable of 50 W; TV antenna cable; impedance matching; probes (paralleled metallic guides) with 0.10, 0.15, 0.20, 0.25, 0.30 and 0.35 m lengths and with two diameters (d1 = 3.2 and d2 = 6.5 mm). For the sandy soil, the best fit was obtained with a 0.30 m-long probe with 3.2 mm-diameter guides, an adjusted determination coefficient, R2, of 0.954. For the clay soil, the best fit was obtained with a 0.30 m-long probe with a 3.2 mm-diameter guides, and an adjusted determination coefficient, R2, of 0.923. The TDR system, proposed for determination of the soil water content within the range between the field capacity and the wilting point, provided the best determination coefficients for the 0.30 m probe in both soils and the studied probe lengths. The proposed TDR system estimated the clay-soil water content with mean relative error of 6.6%, for the 0.30 m probe.

【 授权许可】

CC BY-NC