TREATMENT FOR DEFECTIVE SOILS 



33 



to trees and vines with roots adapted to heavy soils, but difficulty of 

 cultivation, excessive retention of water, and other evils are always 

 present. 



DEFECTIVE SOILS 



Although California soils are predominantly of the depth, light- 

 ness and richness best suited to the growth and bearing of fruit 

 trees and vines, it should always be borne in mind that there are 

 marked exceptions, and failure to observe this fact has resulted in 

 considerable disappointment and loss. There is in California much 

 'land which is bad from a horticultural point of view and it is apt to 

 occur even in the vicinity of lands of the highest excellence. It is, 

 therefore, necessary to advise that the closest examination, to be 

 made before investment, be made in the planting of fruits. 



Although there are instances of deficiency in plant food in Cali- 

 fornia soils and considerable areas of land sterile through excess of 

 saline and alkaline salts, these are usually indicated by the local 

 reputation of the tracts, if the newcomer will take pains to make 

 inquiry. It is rather the more obscure, subsoil conditions which lead 

 to loss or failure, and they may be unknown even to men who have 

 owned or farmed the land for years for ordinary field crops. These 

 defects are, in the main, three : 



Leachy Subsoils. While it is best in all cases to choose deep 

 soils for cropping purposes, it is frequently profitable to grow fruit 

 on soils with defective subsoils. Among these defective subsoils 

 there is frequently encountered, underlying good alluvial loams, a 

 very pervious sand or gravel which allows of a too rapid escape of 

 moisture and plant food. This may result in starving the tree or 

 killing it for want of water. Under such circumstances it is possible 

 with three or four feet of good loam above the gravel to maintain 

 profitably the shallow rooted trees by practicing heavy green 

 manuring and constant summer cultivation to conserve what mois- 

 ture the loam retains and by recourse to irrigation, when required. 



Hardpan. It has frequently been observed that even where 

 hardpan has been blasted prior to tree planting, the evil effects of 

 waterlogging in a rather retentive overlying soil have either killed 

 trees or made them unprofitable. This condition occurs not only on 

 level land but also on rather steep hillsides where on a priori con- 

 siderations it would never be expected. In such cases drainage 

 gives immediate relief and the maintenance of a good supply of 

 organic matter in the soil, with constant summer cultivation, will 

 usually insure good moisture conditions. 



"Plow Sole" or Plow Pan." Constant plowing to the same 

 depth or a failure to break up thoroughly the silty deposits at the 

 bottom of irrigation furrows may in a few seasons produce a hard- 

 ened and difficultly permeable layer of soil known, according to its 

 origin, as plow sole or "irrigation hardpan." This may also be ag- 

 gravated through the treading of stock and fruit pickers. Such 



