Spray deposition and losses in potato as a function of air-assistance and sprayer boom angle

Abstract

Within the Brazilian agricultural scene, the potato crop plays a significant economic role. Modern equipment and the development of improved chemical product application techniques contribute toward the constant search for improved revenue from the potato as a crop. Field experiments were carried out in a random block design of a potato crop of the "Ágata" variety. The aim was to evaluate the effect of air assistance combined to different angles of spray application on the chemical deposition on the potato plant, as well as to assess spray losses to the soil. For this a sprayer with and without boom air assistance was used in the experiments. Boom angles of 0°, +30° and -30° were directed to a vertical position as well as forward and backward movements. The trial plants were sprayed at a volume rate of 400 L ha-1 using JA-4 hollow cone nozzles at 633 kPa and copper oxychloride as a tracer for the deposit evaluation. Trace deposits on both surfaces of leaflets were removed by washing with destilled water and were quantified by atomic absorption spectrophotometry. Spray losses were measured by placing plastic measuring collectors between rows. The deposit levels at different positions in the plant were analyzed by the Hotelling T2 statistical test. Larger deposits were detected at both upper and lower positions of the plant when the spray boom was positioned at 0° and +30° in the presence of air assistance. The presence of air, in addition to the increasing spray deposits in the lower parts of the plant, helped to create greater distribution uniformity. Spray loss was below 4%.