Efeitos da fertirrigação sobre corrosão em aço galvanizado utilizado em pivô central

Abstract

One of the main causes of deterioration and reduction of the lifetime of agricultural equipment is corrosion. In central pivot irrigation systems, corrosion occurs mainly in galvanized steel pipes, causing problems such as reduction of water application efficiency, contamination of irrigation water, leaks and reduction of equipment lifetime. The center pivot is one of the most widely used irrigation systems because it has advantages such as the use of fertigation, which can increase corrosion, once fertilizers in contact with water or moisture become corrosive. This research evaluated the corrosion caused by fertigation in galvanized steel test specimens similar to those used in center pivots, simulating 10 years of fertigation with frequency of 5 times a year and duration of 7 hours, by means of immersion tests in solutions containing 0, 5 and 10 g/l of the fertilizer 20-00-20, in order to obtain the mass loss per area of metallic material, annual average penetration rate in steel and the effect of fertigation on the lifetime of center pivot. The mass loss per area increased with the time of exposure in the corrosive environment and with the fertilizing concentration, the average corrosion rate decreased with the exposure time and there was a slight reduction in the estimated useful life of the zinc coating layer exposed to fertilizer 20-00-20. The results obtained showed that fertigation increased corrosion in galvanized steel used in center pivot pipes.