This study aimed to evaluate the influence of the magnetized water use on the lettuce irrigation management responses, and based on generated data, to evaluate by simulation the influence of soil water retention curve type on the lettuce irrigation management responses. This work was divided into three stages: 1 – determination of field and laboratory soil water retention curves; 2 – lettuce crop irrigation management experiment using soil water retention curve with field data, evaluating different soil water tensions to start irrigation and different water types (magnetically treated water, and non-treated water); and 3 – estimate of the irrigation management responses (simulation) using the soil water retention curve performed in the laboratory (using non-treated water), compared with the experimental results (stage 2). The use of magnetically treated water determined the soil moisture maintenance for a longer time and less irrigation events, leading to less water being applied and electricity consumption. The use of soil water retention curve derived from the field data determined less water and electric energy consumption in the Lucy Brown lettuce irrigation, in comparison to the simulated use of the soil water retention curve from laboratory data.

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The artificial water application through irrigation systems can provide uneven applications, causing excess or deficit in part of the cultivating area. The companies that supply irrigation equipment have been investing in the development of products that optimize the efficiency of application, and consequently the cost of production. The objective of this study was to evaluate the influence of the structural modification of the 3D diffusion arm on the performance and uniformity of a Netafim ™ D-Net ™ 9575 sprinkler. The structural modification made by the company was to allocate bulkheads (teeth) in the diffusion arm, in order to optimize water distribution. In Lavras, state of Minas Gerais, Brazil the experiment was performed, assays with teeth (WT) and no teeth (NT), at three pressures (200, 300 and 400 kPa), with three repetitions. The evaluation of the sprinkler performance was based on the determination of the radial profile of each combination, Christiansen uniformity coefficient (CUC), application intensity, and sprinkler flow. The results indicated that the average application intensities (Ia) of each pressure with the teeth (WT) and without the teeth (NT) of the diffuser are coherent compared to the values indicated in the catalog. The Ia values for all NT tests and for some WT pressures are slightly above that recommended by the Netafim ™ catalog. Overall the diffuser arm WT reduces the range of the water jet. The CUC uniformity coefficient with 300 kPa working pressure for the WT and NT tests achieved the best results according to the objective.

Irrigated agriculture has become a concern, given the scarcity of freshwater. To reduce its water consumption, new techniques and technologies have been proposed. Based on this, the objective of this work was to evaluate the influence of different soil water tensions at initiation of irrigation with magnetically treated water, on ‘iceberg’ lettuce Lucy Brown (Lactuca Sativa L.) development and production. The experiment was conducted in a greenhouse, using a completely randomized factorial design, to evaluate two water types (magnetically treated water – MW and ordinary water – OW) and four soil water tensions at initiation of irrigation (T1 – 15 kPa, T2 – 25 kPa, T3 – 40 kPa and T4 – 70 kPa), with three replicates. Tensiometers were used to estimate soil water tension. The evaluated parameters were: aerial part fresh and dry total mass; commercial head fresh and dry mass, root fresh and dry mass; stem fresh and dry mass; stem length and diameter; percentage of leaves with tip burn, total and commercial yield; water use efficiency related to total and commercial yield; plant exposed area; and dry matter content. Despite achieving greater water use efficiency, the magnetic treatment may have hindered the removal of water from the soil by the crop, especially at increased soil water tension at initiation of irrigation.