SOIL PREPARATION 



83 



purpose. One of the best tools for greenhouse work is 

 the smallest-sized smoothing harrow (Fig. 28) with a 

 second leveling board adjusted behind the last row of 

 disks. When it is desired to use the plow, the lettuce 

 should be planted in long, narrow strips, so that when the 

 successional crops of lettuce are harvested the strips can 

 be plowed, harrowed and replanted with the minimum 

 loss of time. When horse implements are used (Fig. 26), 

 some hand work will be required along the sides and ends 

 of the houses, to secure a finished appearance. 



Spading and raking. In the smaller houses and in 

 most of the large establishments the soil is prepared by 

 the use of the spade and rake. Spading forks are often 

 used instead of spading shovels. Whatever the method 



Fig. 28. Small smoothing harrow. 



employed, the soil should be left in a fine state of division. 



Applying lime. The various commercial forms may 

 be used for the treatment of greenhouse soils. While 

 ground stone lime is most convenient to apply, unslaked 

 stone lime and hydrated lime are used more generally 

 than other forms. Stone lime is simply deposited in 

 small piles in the greenhouses and sufficient water 

 applied to it with a hose to cause prompt slaking, and the 

 lime is then spread with a shovel. There is no better 

 time to apply lime than after plowing or spading and 

 before harrowing or raking. It should not be mixed 

 directly with manure because it will release the ammonia. 



No experiments have been conducted to determine the 



