Doctoral Thesis
DOI
10.11606/T.11.2005.tde-26042005-140149
Document
Author
Full name
Rene Nene Chipana Rivera
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2004
Supervisor
Committee
Duarte, Sergio Nascimento (President)
Botrel, Tarlei Arriel
Cruz, Raimundo Leite
Matsura, Edson Eiji
Miranda, Jarbas Honorio de
Title in Portuguese
Modelagem da dinâmica da água e do potássio na irrigação por gotejamento superficial.
Keywords in Portuguese
água de irrigação
fertilizantes potássicos
fertirrigação
irrigação por gotejamento
modelo matemático
Abstract in Portuguese
Title in English
Dynamics of water and potassium modeling under superficial trickle irrigation.
Keywords in English
drip irrigation
fertigation
irrigation water
mathematical model
potassium fertilizers
Abstract in English
The technique of fertigation application is winning acceptance, mainly in trickle irrigation, due to the advantages that it presents as the possibility of controlling the nutrition of the plants, as the case of the potassium, that is one of the most used fertilizers. However, the description of the transport of water and solute under real conditions presents great complexity, besides the high costs involved in the field researches. Therefore, the present work had as objective develop a mathematical model to simulate the simultaneous displacement of water and potassium applied in the soil under a punctual source. The study was executed in three phases: model development, experimental validation and sensibility analysis. The modeling was based on the numeric solution of the equations that govern the movement of water and the solute transport in the soil, applied from a punctual source, allowing to determine the distribution of water and of the solute in the soil in function of the space and time. These equations were resolved considering a system of control volumes, characterized by the radial and vertical dimensions, considering that the humid bulb is composed for a series of concentric rings. The validation of the model was driven at Soil Physics Laboratory and in a plastic greenhouse of the Department of Rural Engineering of the Escola Superior de Agricultura "Luiz of Queiroz", of the São Paulo University, in Piracicaba - Brazil. The sensibility analysis was made with regard to the individual variations of the saturated soil hydraulic conductivity, initial and saturated soil humidity, dispersivity, retardation factor and emitter flow. It was obtained a good adjustment among the model simulated values and the observed ones, indicating that the movement and distribution of water and potassium applied in trickle irrigation can be modeled mathematically by the solution of the transient flow equations by using the control volumes method. The result of the sensibility analysis revealed that the model is quite sensitive to the soil saturation and initial humidity, regarding the distribution of water. Regarding the potassium distribution, it is quite sensitive to negative variations of soil saturated hydraulic conductivity, emitter flow and retardation factor of the soil, and little sensitive to the variations of the soil dispersivity.