Continuing in the laboratory a greenhouse study of the reaction of percolating solns. with the soil, successive increments of urea solns. were added at regular time-intervals to soil in percolators. With soil previously heated in a moist condition for 48 hrs. and then dried, marked reductions in concs. occurred in the 1st percolate and smaller reductions in the 2d; later percolates showed little variation from the original solns. Adsorption of urea by the soil explains the reductions in the first 2 percolates. In normal soil and soil under toluene the early percolates were likewise markedly reduced. The reductions in concs. of later percolates were nearly constant for a given rate of percolation. These nearly constant reductions are assignable to catalytic activity, which was thermolabile because it was inactivated by preheating of the soil. Wide variations in the concs. of urea at a given rate of percolation had little effect on this catalysis, thereby suggesting enzymatic activity. The reductions in concs. were substantially proportional to the time of contact of soil and the percolating solns. In equilibrium studies with suspensions of preheated soil, amts. of urea adsorbed plotted logarithmically against equilibrium concs. gave points approximating a straight line, thereby indicating adsorption. In incubation studies preheated soil under toluene produced but little ammonia from urea, and without toluene somewhat more. But normal soil under toluene produced much more ammonia and nearly as much as without toluene in the same length of time. Catalysis seemed more important in splitting urea than the direct action of soil microorganisms.