Site-specific chemical application based on the spatial variability of weeds.

Author(s)

Fábio Henrique Rojo Baio

• Document type: Master's Dissertation
• Press: Piracicaba. , gráficos, ilustrações, tabelas.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2002-02-06

Examining board members

Luiz Antonio Balastreire; Ulisses Rocha Antuniassi; Walter Francisco Molina Junior

• Advisor: Luiz Antonio Balastreire
• Field of knowledge: Agronomical Sciences - Agricultural Engineering
• Indexed in: Banco de Dados Bibliográficos da USP-DEDALUS; Biblioteca Digital de Teses e Dissertações - USP
• Location: Universidade de São Paulo. Biblioteca Central da Escola Superior de Agricultura Luiz de Queiroz; ESALQ-BC/t632.58; B162a; 78828

Abstract

The weeds present spatial variability in the field. This spatial variability allows the mapping and the control of these plants on a site-specific basis. The purposes of this work were to develop and to evaluate a method for determination of the time of response of an equipment for site-specific chemical application, to evaluate the herbicide efficiency and economy by using this system, to compare two methods for weed mapping and to analyze the spatial variability correlation between the weed species and the soil fertility attributes. The evaluated method for time of response determination was shown to be practical and fast. The time of response of the evaluated system was 28 s. It was possible to identify and to map six weed species in the field by two different methods. The method of weed mapping by systematic sampling was shown very low, less practical and it demanded a larger time to get the final weed map. The method of weed mapping by weed patch contour was faster than the previous one to get the data in the field and to get the final weed map. However, this method was shown subjective. A prescription map with four herbicide application rates was created according to the spatial variability of weeds. The as-applied map was consistent with the prescription map. The weeds were controlled efficiently. The system evaluated for site-specific chemical application allowed 31,6% of herbicide economy, when compared with the traditio nal method using a single rate for the whole field. There was not an adequate correlation between the spatial variability of soil fertility attributes and the stage of development of weed species. (AU)