RESUMO
This work aimed to evsaluate the influence of raw sanitary sewage (RS) application in closed-end and level-bottom furrows on the distribution of macronutrients and sodium in the soil along its depth. The applied amount of RS was controlled due to the harmful effect of sodium, with a weekly application over three consecutive years. The experimental design consisted of two experimental plots receiving RS, one with alternating the site of effluent application (alternation of inlet and outlet-TFA) and the other without alternating the site of application (only inlet-TFN); and two experimental plots receiving conventional mineral fertilization, both irrigated with public water supply, where one alternated the site of water application (alternation of inlet and outlet-TWA) and the other without alternating the site of application (only inlet-TWN). The inversion of the flow direction with RS application in the closed-end furrows (TFA) provided a better distribution of nutrients in the soil along its length. There was no significant difference in the levels of macronutrients and sodium between the initial and final regions of the furrow soil. In contrast, the fixed flow direction experimental unit (TFN) exhibit a significant difference between the initial and final levels of total nitrogen, phosphorus, potassium and sodium in the closed furrows with mean concentrations of 265.2, 16.2, 46.7 and 110.0 mg dm-3, respectively.
Assuntos
Esgotos , Solo , Nutrientes , Abastecimento de Água , SódioRESUMO
The objective of this work was to evaluate the influence of the form of raw sanitary sewage (RS) application in closed-end and level-bottom furrows on the dry matter yield and macronutrient extraction capacity (extraction of nitrogen, phosphorus and potassium) by the aerial part (stem and leaves) of elephant grass. Fertigation of elephant grass with RS were conducted for 3 uninterrupted years, and the RS application dose was established as a function of the amount of sodium fed to the soil (300 kg ha-1 year-1). In the experimental planning four treatments were established, where two experimental plots received RS and the water demand was complemented by treated water from the public supply network (TW), with and without alternation in the position of RS application in the furrows (TFA and TFN, respectively); and as a control there were two experimental plots in which the plants received conventional mineral fertilization, where the grass was irrigated with TW, with and without alternation in the position of water application in the furrows (TWA and TWN, respectively). The greatest mean dry matter yield (29.9 Mg ha-1 year-1) and mean macronutrient extraction values were found for plants submitted to TFA (688, 102, 508 kg ha-1 year-1 of N, P and K, respectively), compared to those obtained in the other treatments.