PURPOSES OF CULTIVATION 137 



be, and what the special nature of their soils, there are fruit growers, 

 both in northern and southern California, who have for years trusted 

 almost wholly to the cultivator, cutting to a depth of three or four 

 inches, and keep their orchards throughout the year almost in the same 

 state of tilth, never allowing a weed to grow. This practice is, how- 

 ever, becoming less prevalent, and for certain soils the question is 

 practically settled in the minds of nearly all orchardists, while for other 

 soils there is still doubt. For the heavier soils, which continuous shal- 

 low cultivation is apt to render too compact, it is necessary to have re- 

 course to the plow to open the land for proper aeration and penetration 

 of moisture which otherwise would be largely lost by surface run-off. 

 The lighter soils do not require this and they seem to do well with con- 

 tinuous use of the cultivator. It is beginning to be clearly seen, how- 

 ever, that this treatment tends toward the decrease of the humus and 

 the consequent impoverishment of the soil. Its water-holding capacity 

 is also lessened. These facts have induced some growers to change 

 their practice and to take up the plow during late winter or early spring 

 to cover in the growth of green stuff which they allow to grow instead 

 of frequently destroying it with the winter use of the cultivator. Either 

 the fall and spring plowing, or both, followed by the summer use of 

 the cultivator, the most rational and satisfactory practice for most 

 of our deciduous orchards, though there are local conditions and cir- 

 cumstances under which different procedure is preferable. 



SUMMER CULTIVATION 



Whatever the winter policy may be, the essential point in summer 

 cutivation is to preserve the surface layer of pulverised earth. It will 

 not do to have a few inches of clogs, from the size of a pea to that of a 

 goose egg, resting on a hard surface. The finer the pulverization the 

 shallower can be the surface layer, and vice versa, and this is probably 

 one reason why in practice the work of the plow is, in so many situa- 

 tions, found the best foundation upon which to rest the years' cultiva- 

 tion. 



In order to secure this finely-pulverized layer, it is sometimes neces- 

 sary to use what is called a "rubber," where there are many clods which 

 are merely displaced by the harrow or cultivator. There are different 

 styles, and they are generally home-made. The most common form is 

 made of two-inch plank in lengths of three or four feet, bolted or spiked 

 to pieces of four-by-four-inch scantling running crosswise, the edges 

 of the planks lapped like the clapboards which are used for weather 

 boarding. As these edges are drawn over the surface, the clods are 

 rubbed into tilth if they are not too hard and dry. 



But this rubbing may be very undesirable if it leaves the surface 

 smooth and polished. It may reflect the sunheat even to tree-burning, 

 and is apt to form an evaporating surface, which is most to be avoided. 

 The best finish for the land is that produced by a light, fine-toothed 

 harrow, and an attachment of this kind is provided with various clod 

 crushers and cultivators. The result is a surface af loose earth, flat and 

 fine, which approaches very closely an ideal condition. 



