How to prevent the erosion of topsoil
Use the trays constructed for the experience above.
(a) Fill the trays with loose soil and tilt everyone the similar amount. Make furrows with a stick running up and down the hill in single box and across the hill in the other box. Sprinkle each the similar amount. Observe the erosion in every case and the run-off water.
(b) Again fill the trays with loose soil. Water them unless there are well-defined gulleys formed from the running water. Now block the gulleys at intervals with little stones and twigs. Again water and observe the effect of blocking the gulleys