NOVELTY - The machine has a tension line which is connected to the opposed longitudinal ends and is extended from a carriage (18) in opposed longitudinal directions. A drive system is provided for driving the tension line. The carriage is caused to be moved from one end of the machine main portion to an opposite end. A cutting blade (36) is drawn from one end of the series of the grates (24) to the opposite end. A bottom layer of compost of a desired thickness is cut. Compost with the desired thickness is discharged down through the series of grates.    USE - Worm composting machine of composting system (claimed).    ADVANTAGE - The design and operation of the worm composting machine is improved effectively.    DETAILED DESCRIPTION - A series of cross beams in the support frame are extended transversely. The support frame is provided with side and end frame elements. The side walls and end walls are connected to the side and end frame elements. A series of grates are rest horizontally on the support frame above the cross beams. The grates are primarily open and positioned on the support frame in series with a longitudinal gap formed between the edges of the grates along a longitudinal center line of the frame. A guide channel is formed through the length of the series of grates. A carriage is movable along the frame through the length of the series of grates and is provided with two opposed longitudinal ends. A keel is slidably positioned within the guide channel and is provided with a length no greater than about 15 inches and the carriage. A compost cutting blade is extended transversely across the width of the series of grates and spaced above the grates by a selected distance. The carriage driving mechanism is provided with a tension line. The keel is provided with the length no greater than about 12 inches. The cutting blade his provided with a cross-sectional shape convexly curved at an upper side. The cutting blade is planar at a lower side. The ends of the cutting blade is provided with a spacer extending down from the lower side of the blade and positioned to rest on and slide on the grates to maintain the ends of the cutting blade spaced above the grates by selected distance. The outer sides of the series of grates are provided with a flat horizontal longitudinal rail on which the spacers of the cutting blade rest. The support frame is provided with a length about twenty feet. The support frame is provided with length about forty feet. The cross beams are provided with the raised locator protrusions at upper sides of the cross beams. The protrusions are extended up into openings of the grates for properly locating the grates in the frame. A frame extension (12) is set at one end of the support frame for supporting a motor (28). A second frame extension (14) is at an opposite end of the frame. A tensioner is supported on the second frame extension and connected to the tension line. The tension in the tension line is adjusted. A gear box (30) is connected to and driven by the motor. A pulley (32) is driven by the gear box. The tension line is extended around the pulley. The adjustable tensioner is connected to the tension line. A release coupling in the drive system is provided for disengaging the drive system if a preselected load occurs during movement of the carriage by the drive system. An INDEPENDENT CLAIM is included for a composting system has worm composting machine and a compost pile with live worms. The compost pile is about 24 inches deep and is positioned within the worm composting machine.    DESCRIPTION OF DRAWING(S) - The drawing shows a top view of the compositing machine.    Frame extensions (12,14)    Carriage (18)    Grates (24)    Motor (28)    Gear box (30)    Pulley (32)    Cutting blade (36)