TREATMENT OF SUBSOIL 



107 



no palatable figs at all last season, and what there 

 were ripened before the middle of August. For 

 five years the ground had been worked solely with 

 a disk, no fertilizers being added. 



A most experienced nurseryman seriously con- 

 tends that fig roots grow in three layers, the first 

 being surface feeders just under ground, the second 

 intermediate about six inches below, and the third 

 strata about a foot further down. Trees on his 

 farm do not show such systems of growth, nor is 

 there any data justifying their division into layers. 

 The fact is, figs form a symmetrical system of roots 

 which tend downward, and their direction is only 

 diverted when checked by obstacles or impervious 

 clay. 



When soil is to be developed to greater depths, 

 what methods should be used? The question is a 

 general one, and mostly beyond the purpose of this 

 work. Ordinarily it takes about three years to so 

 reduce subsoil that it will contribute plant food. 

 If it could be thrown repeatedly in the air it would 

 tame much faster. Deep plowing will bring it to 

 the top, but dangers result, as has been suggested. 

 If it contains toxic acids, or noxious compounds, in 

 excreta of former plants, such might seriously inter- 

 fere with tree growth. Then subsoil turned to the 

 surface forms hard lumps, hindering cultivation, 

 promoting evaporation, and being unpleasant. A 

 better method is to follow one plow with another, 



