DEPTH OF PLOWING 35 



Surface cultivation should immediately follow both 

 spring and fall plowing. 



34. Mulching. The use of well-rotted manure or 

 straw, spread over the surface as a mulch, prevents 

 evaporation. In forests the leaves form a mulch 

 which is an important factor in maintaining the water 

 supply. In order that a mulch be effectual, it must 

 be compacted, a loose pile of straw is not a mulch. 

 In reclaiming lands gullied by water, mulching is 

 very beneficial. A light mulch may also be used to 

 encourage the growth of grass on a refractory hillside. 

 When land is mulched, evaporation is checked. Sur- 

 face cultivation and mulching may be advantageously 

 combined. 14 



Per cent, of water in 



Mulched straw- 

 berry patch. Unmulched. 



Soil 2 to 5 inches 18.12 11.17 



" 6 to 12 " 22.18 18.14 



" 12 to 18 " 24.31 21.11 



35. Depth of Plowing. The depth to which a soil 

 should be plowed in order to give the best results must, 

 of necessity, vary with the conditions. Deep plowing 

 of sandy land is not advisable, particularly in the 

 spring. On clay land deeper plowing should be the 

 rule. The longer a soil is cultivated the deeper and 

 more thorough should be the cultivation. While 

 shallow plowing is admissible on new prairie land, 

 deeper cultivation should be practiced when the land 

 has been cropped for a series of years. Also, the 

 depth of plowing should be regulated by the season. 

 In the prairie regions, and in the northwestern part of 



