In this paper, an automatic Smart Irrigation Decision Support System, SIDSS, is proposed to manage
irrigation in agriculture. Our system estimates the weekly irrigations needs of a plantation, on the basis
of both soil measurements and climatic variables gathered by several autonomous nodes deployed in
field. This enables a closed loop control scheme to adapt the decision support system to local perturbations
and estimation errors. Two machine learning techniques, PLSR and ANFIS, are proposed as reasoning
engine of our SIDSS. Our approach is validated on three commercial plantations of citrus trees located in
the South-East of Spain. Performance is tested against decisions taken by a human expert.