The effect of domestic sewage effluent and planting density on growth and yield of prickly pear cactus in the semiarid region of Brazil

Abstract Agricultural and livestock productivity in the semiarid region depend on the occurrence of rainfall, soil fertility and forage supply. The use of domestic sewage effluent can be used as an alternative source of water and nutrients for crops growth in the semiarid region. This study aimed to evaluate the effects of irrigation with treated domestic sewage effluent on the growth and biomass production of prickly pear cactus (Opuntia tuna L.) at different planting densities. The experiment was carried out in a randomized block design, arranged in a 3 x (4 + 1) split-plot scheme, with four replicates. The treatments consisted of three planting densities (66,667, 52,282 and 33,333 plants ha−1) and four frequencies of application of irrigation (2.3 days with well water and 7, 14, and 21 days with sewage effluent) and a control treatment (rainfed condition). Irrigation with domestic sewage effluent allowed profitable production of prickly pear cactus and improved its growth and forage production compared to rainfed and irrigated with drinking water, regardless of the irrigation interval or plant spacing. Dense cultivation 66,667 plants ha−1 increase the biomass production of the prickly pear cactus cultivar ‘Orelha de Elefante Mexicana’ under irrigation with domestic sewage effluent at 7-day intervals.