TIIK TILLAGE OF THE SOIL 69 



or pulverize the lain I to a ,:rr<'at depth, tlie sub- 

 soil plow is run in tlio furrow behind the ordi- 

 nary i»low. Subsoilinjj: provides a deeper bed 

 for n^ots, breaks uj) tlie Juii-d-pan, and (b'ies the 

 ^oil. More pcrnianeiit results an* usually ob- 

 taiue<l by thorou«;h undrr-drainage. 



Ah. liij siirfitrt •irin'knui tools 



98. Tilla^ire by means of surfaee-working 

 tools — as hoes, rakes, eultivat(U"s, harrows, clod- 

 i-rushers — has the f<>llo\vin.i,' objects: {(i) to 

 make a bed in which seeds can be sown or jdauts 

 set, (b) to cover the seeds, (r) to jmlverize the 

 ground, (d) to establish and maintain an eai'th- 

 muleh, (e) to destroy weeds. Aside from these 

 speeifie benefits, surface tillap- contributes to 

 the general betterment of soil conditions, as 

 outlined in 87, HS, 89. 



!>!*. In nuikini,' the earth-nuilch (the im- 

 portance of whi<'h as a saver ni' moisture is 

 fully explained in 82, 8.'J), the other obj«»cts of 

 surfaci' tillage are also secured ; therefore we 

 may eonfme our attention to the earth-mulch foi- 

 the present. The mulch is made by shallow 

 tdlage — about three inches deep. In field coiidi- 

 uons — before the seeds are sown. The first til- 

 lair«' after plowing is usually with a heavy and 

 coarse tool, — us a clod-crusher, cutaway harrow, 



