Effects of fertigation on corrosion in galvanized steel used
in center pivot systems
Karina V. Rodrigues, Luiz A. Lima and Michael S. Thebaldi
ABSTRACT
One of the main causes of agricultural equipment deterioration is corrosion. In center pivot irrigation
systems, deterioration mainly occurs in galvanized steel pipelines. Fertigation can increase corrosion
because fertilizers become corrosive when exposed to water or moisture; this corrosion reduces the
service lifetime of the equipment. In this study, fertigation-induced corrosion was evaluated in
specimens of galvanized steel (similar to that used in center pivot systems), simulating 10 years of
operation comprising 5 fertigations per year with a duration of 7 hours each. Immersion tests were
performed in solutions containing 0, 5 and 10 g/L fertilizer concentrations to obtain the mass loss per
unit area of the metallic material, which increased in response to increases in both the exposure time
in the corrosive environment and the fertilizer concentration. The results showed that fertigation
increases corrosion in galvanized steel and the higher fertilizer concentration leads to a higher
corrosion, since, for the same exposure time, the mass loss for the 10 g/L solution was 43% greater
than the 5 g/L.
Karina V. Rodrigues (corresponding author)
Luiz A. Lima
Michael S. Thebaldi
Department of Water Resources and Sanitation,
Federal University of Lavras,
Caixa Postal 3037, Campus Universitário, 37200-
900, Lavras, MG,
Brazil
E-mail: karina.vilela02@gmail.com
Key words | exposure time, galvanized steel, immersion test, irrigation water quality, mass loss,
zinc coating
INTRODUCTION
The use of mechanized irrigation systems has grown in
recent years. According to the WBCSD (), by 2050, irri-
gated agriculture on 16% of the total cultivated area will be
producing approximately 44% of the world’s food. Accord-
ing to Frizzone et al. (), worldwide, in total 35 million
hectares are irrigated by sprinkler irrigation systems, with
the center pivot system representing 23% of this area. In
addition, Wood () presents that the center pivot
market is expected to grow by 15.8% by 2026.
According to the manufacturer Valley, the expected life-
time of galvanized steel pipelines used in center pivots is
approximately 25 years, although degradation problems
have been reported after less than 10 years of use. These
degradation problems occur due to the high number of
annual operation hours, the quality of the irrigation water
and the supply of fertilizers via irrigation (Valley ).
The corrosion potential can increase significantly with
some factors (e.g. solution pH, dissolved oxygen and chlor-
ide ion concentration, temperature), which are often
related to the presence of oxides, hydroxides and carbonates
formed by the reaction of irrigation water with fertilizers
(Nwoye et al. ).
Fertigation is the application of fertilizers, soil amend-
ments, or other water-soluble products through an
irrigation system. The use of fertigation can increase cor-
rosion in galvanized steel pipelines because fertilizers
become corrosive when exposed to water or moisture (Oki
& Anawe ). In center pivot irrigation systems, corrosion
can decrease equipment efficiency, cause irrigation water
contamination, leaks and reduce system lifetime, leading
to increased operational costs due to maintenance and
equipment replacement (Eker & Yuksel ).
1189 © IWA Publishing 2020 Water Supply | 20.4 | 2020
doi: 10.2166/ws.2020.029
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