158 STATE BOARD OF HORTICULTURE. 



H. D. MOORE, of Redlands: Hardpan within two feet of the 

 surface will eventually ruin any orchard. Its effects will 

 probably be noticed by the third or fourth year. 



DIGEST OF DISCUSSION BY THE CLUB: The question doubtless 

 refers to the natural hardpan underlying the red mesa soil 

 common in California, and not to the artificial hardpan so 

 called, which is formed in orchards by the tramping of horses 

 used in cultivating. The latter occurs immediately below the 

 cultivated stratum, and is caused by driving over the ground 

 too soon after rain or irrigation. The natural hardpan may 

 be divided into three classes, namely: gravelly, sandy, and 

 clayey hardpan. It is found at varying depths, and runs 

 from a few inches to several feet in thickness. Analysis shows 

 it to be deficient in nitrogen, but rich in potash and phosphoric 

 acid, the same being true of the looser soil found underlying 

 it. In many cases it is impervious to either water or roots, 

 and consequently marks the downward limit of the soil capable 

 of holding moisture or of yielding plant-food to the tree. 



QUESTION: Is it advisable to break up this hardpan, and will 

 it stay broken up? 



PROF. HILGARD: Yes, to both. 



MR. REED: Other conditions being markedly favorably, yes. 

 If well done it will stay broken up. 



MR. MOORE: If an orchard is already planted in such soil, 

 it would be advisable to put in three or four cartridges at equal 

 distances around the trees. The soil has been found to pack 

 down hard again in three years after blasting. 



C. E. MOSHER. of Pasadena: Yes. Hardpan once broken 

 up will not form again. 



THE CLUB: Yes, if the stratum is not too thick. The grav- 

 elly hardpan, which is probably the hardest for roots or water 

 to penetrate, is the most easily and permanently broken up. 



QUESTION: What is the best method of blasting in such cases, 

 and what is the expense? 



PROFESSOR HILGARD: Bore into the hardpan and use one- 

 half pound of No. 2 giant powder in each hole. 



MR. REED: Giant powder. Expense depends on. condition 

 of hardpan. 



MR. MOSHER: I took the contract for blasting the hardpan 



