1. AN EARTH-TILLING IMPLEMENT ADAPTED TO BE TOWED BEHIND A TRACTOR, SAID IMPLEMENT COMPRISING IN COMBINATION: A FRAME EXTENDING LATERALLY OF THE DIRECTION OF TRAVEL OF SAID IMPLEMENT, A PLURALITY OF ELONGATE SKID MEMBERS EXTENDING LONGITUDINALLY BENEATH SAID FRAME AND DEPENDING FROM SAID FRAME AT LATERALLY SPACED-APART POSITIONS THEREON AND AT LEAST PARTIALLY SUPPORTED SAID FRAME FOR TRAVEL ON THE GROUND SURFACE, A PLURALITY OF ROTARY CULTIVATOR ELEMENTS ROTATABLY CARRIED BY SAID FRAME WITH AT LEAST ONE SAID ELEMENT BEING POSITIONED BETWEEN EACH ADJACENT PAIR OF SKID MEMBERS, MEANS CARRIED BY SAID FRAME FOR ROTATING SAID CULTIVATOR ELEMENTS, AND A BED-SHAPING ELEMENT MOUNTED ON EACH SAID SKID MEMBER, SAID BED-SHAPING ELEMENTS INCLUDING A PAIR OF OPPOSITE SIDEWALLS JOINED TOGETHER ALONG THE FRONT END OF EACH AND FLARING OUTWARDLY AWAY FROM ONE ANOTHER IN A DIRECTION REARWARDLY FROM SAID FRONT END AND UPWARDLY FROM SAID SKID MEMBER SO THAT SAID SKID MEMBER AND SAID BED-SHAPING ELEMENT COACT TOGETHER TO FORM A GENERALLY FLAT-BOTTOMED IRRIGATION DITCH WITH OUTWARDLY SLOPING SIDEWALLS.