30 HORTICULTURE, FORESTRY, FLORICULTURE 



to give the best results, the spring-tooth or wheel harrow should be 

 run once and then the weeder twice or three times. The weeders with 

 straight teeth do better work in the orchard than those with curved 

 teeth. 



Some of these tools are perhaps too expensive for the small 

 grower, and under such conditions two or more should join and 

 purchase and use them together. Any of the above implements if 

 properly housed when not in use and the wood parts kept painted 

 should last a long time and do the work for many small growers. 

 (Mass. E. S. B. 82.) 



Effect of Proper Cultivation. (a) To give the plants one desires 

 to grow all the light, air, and moisture that they can use by keeping 

 out of their way all competitors in the shape of weeds. (6) The 

 most common source of injury to our crops comes from drought. Soil 

 that is compact will transmit water upward by capillary attraction 

 much more readily than soil that is somewhat loose, and very loose 

 dry soil loses scarcely any water in this way. This is the chief reason, 

 and by many regarded as the only reason, for cultivation. The loose 

 top soil acting as a mulch prevents the evaporation of water from the 

 compact earth below. The extent of this protection is shown in the 

 following table. 



(c) The working of soils opens them up so that the air can get 

 in and assist in rendering available the plant food locked up in them 

 in an insoluble form. This is an important function of tillage. The 

 soil is a great laboratory in which many complex changes are con- 

 tinually taking place. Its continued cultivation sometimes affects 

 it injuriously by oxidizing all the humus (decayed organic matter) 

 and leaving it in a condition in which it washes badly and will not 

 hold moisture. A good illustration of this change is in the fact that 

 newly cleared land planted to orchard trees seldom wash badly until 

 the decayed organic matter in it has become so thoroughly oxidized 

 that it no longer holds the soil together. After this organic matter 

 has disappeared, clay soils lose their loose porous texture and become 

 hard and destitute of moisture. 



Growing Trees in Sod. This practice is not to be generally rec- 

 ommended, and yet there are sections where apples do exceedingly 

 well when grown in sod or when mulched. In other sections, as on 

 the high steep clay bluffs along the Mississippi River, trees may be 

 grown to great perfection by spading up the soil about them for a 



