COMPOSTING PROCESSES OF LEAF MIDRIBS SALAK (SALACCA EDULIS) WITH SOME ACTIVATORS. A research entitled “Composting Processes of Leaf Midribs Salak (Salacca edulis) with some Activators”, was conducted at Greenhouse Faculty of Agriculture, University of Muhammadiyah Yogyakarta, from June 2016 up to August 2016.These research were arranged in Completely Randomized Design (CRD) with the four treatments: activators EM4; cow manure; rice straw compost; Urea; and without activator treatment, and each treatment was repeated 3 times.The results showed that all kinds of Activators give real effect to all parameters of leaf midrib bark compost and EM4 is an activator of the nicest in the process of composting leaf Midrib Salak.