Dispositivo de baixo custo para automação de sistema de irrigação e sua avaliação na produção de milho verde orgânico

Abstract

Water is a scarce natural resource in certain regions and indispensable to the survival of man and other living beings on the planet. Agriculture is the human activity that employs more water and usually the irrigator does not adopt a rational irrigation management. The aim of this work is to research an equipment that promotes the efficient use of water and for this purpose we evaluated the Simplified Trigger for Irrigation at two stages: 1- in organic production of unripe corn on the field and 2- in the assay of the Trigger with sensor protection with fabric. The experiment with unripe corn consisted of 2 x 2 factorial in five randomized blocks. The first factor was the genotype (AG 1051 corn and Eldorado corn) and the second factor was the difference of levels between the pressostate and the sensor (the pressostate at 40 and 90 cm, resulting respectively in tensions of 4 and 9 kPa). Resulting in this way, four treatments: AG 1051 tension 4kPa, A4; AG 1051 tension 9 KPa, A9; Eldorado tension 4 kPa, E4 and Eldorado tension9 kPa, E9.The output variables evaluated were: yield of ears with leaves; weight and length of ear with leaves, weight and length of ears without leaves; weight and length of ear without the apical end; ear diameter, grain depth and grain color. From 38 days after planting (DAP) some triggers began to malfunction in the following sequence: A9, B9 and E9, respectively, in 38, 39 and 46 DAP. The problem consisted that the trigger was a long period without activation or when it was activated adelayed shutdown happened. Treatment E4 showed unsatisfactory performance at 71 DAP and A4 worked fine during the time of research.The difference was significant (p< 0.05) between treatmens of tension 4KPa and 9KPa for the number of rows of grain per ear. Due to the problems presented mainly in 9KPa plots, it was not possible to attribute the difference in the rows to the tension.The other variables did not show significant difference (p>0.05) between treatments.The assay of the Simplified Trigger with protection of the sensor with fabric was composed of 4 plots, each mounted in a plastic pot of 8.26 liters, and each pot received a trigger; 2 triggers had their sensors protected with fabric. Two were installed without protection. Sensors were installed at 4.0 cm depth, adopting triggering tensions of 3 or 9 Kpa at different phases. The assay was not capable to simulate the sensor's loss of sensibility verified at field conditions, and because of that, it was not possible to evaluate whether the sensor's protection could mitigate its loss of sensibility. It was observed at 160 days after the installation of the assay that the protective fabric was in decomposition, and that impedes its use as protection for the sensor