70 



case of sidehill ditches. Theoretically, it is intended to have the surface 

 between these two furrows leyel so that there will be no chance for the 

 water to run off over the surface. On a small soale this levelling can 

 be done with a horse shovel, and the land thus put at once into a con- 

 dition to prevent washing. In this case the banks of the terrace are 

 sodded or seeded with grass to prevent them from washing. In field 

 practice, however, the soil is moved gradually with a plough, the fur- 

 row being thrown always downhill and the soil gradually worked 

 down to a level plain. There are several forms of reversible ploughs 

 which are admirably adapted to this purpose, being turned retdily 

 from a right to a left handed plough, so that in going back and forth 

 the furrow is always thrown downhill. It requires, of course, a num- 

 ber of years of such cultivation to .get the surface into even approxi- 

 mately a level condition, but with patience and thorough cultivation 

 the soil very quickly assumes a comparatively level aspect, and erosion 

 is reduced to a minimum. This is a more expensive method, but if 

 intelligently done it is much more efficient and much more durable 

 than depending upon sidehill ditches to prevent erosion. As was 

 said in the case 01 the sidehill ditches, unless this work is well done 

 it had much better be left undone, as it may seriously injure the 

 field. 



Where erosion has proceeded so far as to render the land at present 

 unfit for cultivation, ir where the land is not needed for cultivation 

 and it is desired to prevent erosion, the land should be given up to 

 trees, heibs, or grasses of some kind according to one or other of the 

 following methods. 



RECOVERING GULLIED HILLSIDES BY REFORESTATION. 



Forest giound is cot subject to this erosive action of the rainfall 

 because in a forest a large part of the rainfall never reaches the soil 

 as 20 or 3u per cent, is intercepted by the foliage ard evaporated be- 

 fore it reaches the ground I he rainfall which reaches the surface is 

 rapidly absorbed, as the soil is kept granular and loose and much 

 more of the water is carried off by underdrainage rather than by sur- 

 face drainage. 



The iorest covering protects the soil in the following ways : 



(1) By preventing rain from falling directly upon the soil, the fo- 

 liage of tie tree crowns intercepting and breaking its force, the water 

 reaching the soil more gently from the leaves and along the branches 

 and trunks of the trees. 



(2) By interposing a loose cover or mulch of litter formed by the 

 fallen leaves and branches, which breaks the direct force of the rain- 

 drops and keeps the soil from being compacted or puddled by their 

 blows, 



(8) The deeply penetrating roots, and holes left from decayed stumps 

 and roots oi trees, assist in this underground drainage. 



(4) The litter with the stumps and projecting roots and trunks of 

 trees prevent the water from rapidly running over the ground and 

 from gaining the momentum and force which is necessary in order to 

 erode and gully the soil. 



If the forest floor is not disturbed by fire, nor the litter trampled 

 and cc mpacted by cattle, it always reduces rapid surface drainage and 

 largely, if not entirely, prevents erosive action. 



