Management of fertirrigation in a protected environment for the control of salinity for the tomato crop in sandy-clayey soil

Author(s)

Pedro Róbinson Fernandes de Medeiros

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2010-12-13

Examining board members

Sergio Nascimento Duarte; Rubens Duarte Coelho; Raimundo Leite Cruz; Jarbas Honorio de Miranda; Enio Farias de Franca e Silva

• Advisor: Sergio Nascimento Duarte

Abstract

In protected environment conditions, the control of salinity and the fertirrigation management mingle themselves, because most of times the fertilizer salts are the main responsible for the salinization. With the periodical monitoring of the soil solution, the electrical conductivity and the concentration of specific ions can be determined. Among the techniques of extraction of the soil solution the porous cup extractor stands for its practicality in the field, low cost, easy-handling, and good precision. The aim of the research was to calibrate and evaluate the use of porous cup extractors, for the soil solution monitoring in order to aid the management of fertirrigation and the control of the salinization, as well as, study the effect of different levels of salinity, obtained based on artificial curves of soil salinization, on the tomato crop using Débora Plus. The plants were subjected to the following treatments: six initial levels of soil salinity induced by fertilizer salts (S1 = 1,0; S2 = 2,0; S3 = 3,0; S4 = 4,0; S5 = 5,0 E S6 = 6,0 dS m-1). and two types of fertirrigation management, the traditional (M1) and a fertirrigation management with the control of the level of soil salinity throughout the crop cycle (M2); in order to observe if the management M2 is able to maintain the salinity of the soil to desired levels. The Statistic design adopted was the randomized complete block with four repetitions, leaving the studied factors arranged in the factorial scheme 6 x 2, total 48 plots for each protected environment. This study was carried area in the experimental at the Biosistems Engineering Department at ESALQ/USP, Piracicaba, SP. It has been observed that porous cup extractor could monitor the concentration of ions in the soil solution, as well as how to direct the fertirrigation management M2, with the maintenance of the salinity in desired levels. The levels of soil salinity from the accumulation of fertilizer salts affected directly the variables: water consumption, production and the vegetative development of the plants, the pH and the oBrix of the fruit and the pH and the nitrate concentration (NO3 -) of the soil solution. It can be seen that the electrical conductivity maintenance in an excellent level of salinity really promotes the increase of productivity when it contrasts with the traditional fertirrigation management M1, in a protected environment with sandy-clayey soil. (AU)