32 CALIFORNIA CITRUS CULTURE. 
Marker or Furrower. The marker, for making the irrigation fur- 
rows, is not unlike the cultivator in strength and design, except that 
it carries on its beam only two, or three, sometimes four or five, stout 
bread shovels, depending on the number of furrows desired. It is a 
common practice among smaller growers to alter the cultivator each time 
marking out is necessary by the mere substitution of shovels for the 
teeth, reversing the operation again before cultivation is necessary. 
Thus one tool serves a double purpose. 
The marker may be extended in the same way as the cultivator. 
Subsoiler. (Fig. 15). This is a most important tool in the citrus 
orchard, and yet it is probably the tool that has been used least of all. 
Cross subsciling to a depth of from sixteen to eighteen inches at right 
angles to the irrigation furrows and midway between the trees greatly 
facilitates deep irrigation and improves the aeration of all of the soil. 
Fic. 15.--Subsoiler at work in an orchard. (After Lelong.) 
An occasional subsciling, say every third year, of the entire cultivated 
area at intervals of two feet and in two directions to a depth four 
inches below the deepest plowed and cultivated depth will break up 
plow sole or irrigation hardpan and supply the much needed air that 
is too often shut out from the roots. 
Drills. The seceding of cover-crops is usually done with the drill. 
The ‘‘disk’’ drill instead of the ‘‘hoe’’ drill has many advantages 
where trashy ground may be encountered. 
Commercial fertilizer is usually drilled into the soil and to as great 
a depth as possible. A tendeney to believe in applying a part of the 
