COFFEE UNDER IRRIGATION. 19 



the trees. The drying is completed on mats after it has been shaken 

 down upon cloths spread under the trees, an economical method of 

 nicking. The Arabs consider the dried pulp an acceptable addition 

 to the beverage, only the parchment being winnowed out. Most 

 authors admit that the method of curing may explain the excellence 

 of Arabian coffee, but such a plan can not be followed except in a dry 

 climate. Under ordinary tropical conditions the seed will germinate 

 or rot soon after falling to the ground. Some writers contend, how- 

 ever, that the traditional superiority was not caused by differences in 

 the crop or the methods of growing and handling it, but by the fact 

 that when the Arabian coffee reached Europe it was already two or 

 three years old, owing to slow circuitous routes of travel by way of 

 India. That the Arabian conditions are not really favorable for the 

 vigorous growth of the plant is indicated by the fact that a large pro- 

 portion of the product is pea berry or caracolillo, the shape of which 

 results from the ripening of but a single seed instead of two from each 

 flower. The large proportion of pea berry in Porto Rican coffee is 

 also an indication of degeneracy, but the cause is entirely different, 

 namely, overshading under conditions of ample or excessive moisture. 



The success of coffee culture in Mexico, another semiarid country 

 where irrigation and shade are locally necessary, as in the State of 

 Colima, is further evidence that while drought is often a real danger 

 to the coffee planter, the amount of moisture necessary for productive- 

 ness and good quality has been overestimated. The great extension of 

 the industry in the moist tropics has probably resulted in the neglect 

 of some of the drier regions, such as the southern slopes of Porto Rico, 

 where, by proper methods of cultivation, coffee could probably be 

 made to grow as well, or better, than in the more moist areas to which 

 it is now confined. Moreover, it is not improbable that any diminu- 

 tion in quantity would be more than compensated by superior quality. 



Even in regions where the presence of shade trees has seemed to be 

 necessary to the life of the coffee, it is entirely probable that the chief 

 benefit results from the retention of moisture in the soil, so that shade 

 is sometimes to be justified as a substitute for irrigation. Cases are on 

 record of plantations which had thriven well for several years, but 

 were then completely ruined by a single dry season of special severity. 

 The interference of underlying rocks with the taproots of the trees 

 has been alleged as the cause of damage, but it is far more reasonable 

 to believe simply that the effects of drought were more severe on 

 account of the shallowness of the soil, 1 since it is a well-known fact 



1 In the Kona district of Hawaii coffee is said to thrive and produce well entirely 

 without shade, but droughts are prevented by a gentle daily shower at 2 o'clock. 

 The total rainfall is, however, less than 100 inches at an elevation of 1,700 feet, while 

 along the coast below no rain falls. At a similar altitude in the Olaa district the 

 annual precipitation reaches 250 inches, though there are occasionally several days 



