ATL83LA231

The owner/student plt & his instructor (CFI) were on a dual instructional flt & proceed to an arpt with a wet grass rwy to practice landings. The rwy was 2200 ft long & had 50 to 60 ft trees at the apch end that had been cut to aprx 25 ft AGL. The 1st apch (for a touch-and-go landing) was high, so a go-around was made. The 2nd apch was better, but the student still touched down aprx 1050 ft down the rwy. At that point, the CFI told the student to make a full stop landing rather than a touch-and-go. The student applied brakes, but felt little reduction in ground speed. The CFI then took control & applied hard braking. He started s-turns but could not stop on the remaining rwy. Eventually, the acft departed the rwy in a skid, hit a ditch & the right main gear collapsed. No evidence of a preimpact malfunction or failure of the brakes was found. According to the acft handbook, 1650 ft was required to stop on dry pavement when landing over a 50 ft obstacle.