Qualidade do solo cultivado com palma forrageira e irrigado com água residuária tratada

Abstract

Semi-arid region is characterized by having a potential water demand from crops that is much higher than precipitation, which subjects all plants to intense water deficit. This sets up an immense challenge for production of fodder to feed cattle, goats and sheep. Therefore, the use of treated wastewater (ART) is a technically viable option to replace fresh water, providing, in addition to saving good quality water, the increase of nutrients existing in ART in the soil. However, the effect of ART use on soil quality is still little known. Given the above, this study aimed to identify possible microbiological and chemical changes in the soil irrigated with ART and with the cultivation of three species of cactus pear: Nopalea cochinillifera (miúda), Opuntia stricta (Mexican elephant ear) and Opuntia ficus-indica (Giant cactus pear); intercropped with four species of legumes: Canavalia ensiformes (L.) DC (jack bean), Clitoria terneatea L. (cunhã), Cajanus cajan (Guandu bean) and Moringa oleifera Lam. (Moringa), in a randomized block design, with a 3x4 factorial arrangement (3 cultivars of cactos pear x 4 of legumes), with six replications, and was part of a research implemented in a property located in Guanambi, BA, in which the effluent comes from the Effluent Treatment Station of the same municipality, from Company Baiana de Águas e Saneamento S.A. The irrigation management adopted was with controlled deficit, applying only 30% of the reference evapotranspiration – ETo and physical properties (texture) were evaluated to characterize the area; chemical (MO, P, K, Na, Ca, Mg, Al, B, Cu, Fe, Mn, Zn, P-rem, EC, H+Al, SB, t, T, V, m) and biological properties (soil basal respiration, microbial biomass carbon, qCO2, acid phosphatase enzyme and AMF) to assess soil quality. During the experiment period (2021 to 2023), it was possible to observe changes in pH, MO, K, Na, Mg, Al, Fe, Mn, CE, SB, t and T. There was an increase in soil basal respiration (18 months) and in CBM (12 months), while acid phosphatase (18 months), qCO2 (12 months) and AMF (18 months) were not altered by the application of ART. Through the study it was concluded that the use of treated effluent in the studied period favored the soil microbiology, but increased the rates of some chemical parameters such as Na and Al and decreased the pH, therefore, there must be frequent monitoring.