125 



iDecome more vis^orous and productive when the competition of the 

 masses of other vegetation is removed. 



That sunlight is necessary for the processes of plant assimilation, 

 that the sugar content of vegetable tissues depends upon access to 

 H^ht, and that sugar is the material from which most of the alkaloids 

 and other plant substances are elaborated, are well-known facts indi- 

 cating the necessity of light for a maximum of functional activity. 

 Even those who advocate the use of shade admit that the yield is dimin- 

 ished, though the existence of compensating advantages is maintained. 

 In Java the largest trees are described as growing without shade on 

 terraced, carefully cultivated mountain sides with the slopes grassed 

 over to prevent washing. The coffee is planted 25 feet apart, and 

 permitted to grow to its full height — sometimes reaching 30 or 40 feet. 

 These giant trees bear each a crop which, when cured, weighs 6 or 7 

 pounds. 



The production without shade of the most valuable grades of coffee 

 show that the claim that shade is a necessity to the production of coffee 

 of good quality cannot be admitted. 



However untenable may be the position of those who argue that 

 shade is directly beneficial to the coffee tree, the possibility is not ex- 

 cluded that shade in coffee plantations may often be indirectly benefi- 

 cial by conserving soil moisture, keeping down the growth of weeds 

 and grass, preventing erosion, protecting the coffee trees from the vio- 

 lence of the wind, and other ways. 



Prof. Cook's general conclusions are, that there is no basis in reason 

 or in observed fact for the belief that shade is a general necessity for 

 the coffee plant, even when grown at low elevations. On the contrary 

 it is extremely probable that the beneficial effects resulting from 

 shade are quite apart from the shadow cast upon the coffee tree. 



The beneficial effects connected with shade arise from the protec- 

 tion afforded against drought, erosion and winds. The planting of 

 shade trees for these purposes is accordingly determined by local con- 

 ditions of climate and soil, and furnishes no reason for the general 

 planting of shade trees. 



In regions not affected by injurious climatic extremes the planting 

 of shade trees is justified from the cultural stamlpoint only by the 

 increased fertility imparted to the soil by means of the nitrogen-fixing 

 root tubercles of leguminous species. This view has not been made the 

 subject of experimental demonstration, but it seems to accord with all 

 the facts thus far ascertained. 



The benefits of leguminous fertilizing are quit? apart from the shad- 

 ing of the coffee, and under suitable cultural conditions are also to be 

 secured from shrubs and herbs belonging to the same natural family. 



The relative utility and availability of the various shade trees and 

 soiling crops is a subject of vast importance in coffee culture and in 

 other agricultural industries of the tropics.. 



The combinations of such cultures as coffee and cocoa with legumin- 

 ous trees and plants of maximum cultural and commercial value 

 afford many complex, scientific, and practical problems bearing upon 

 the rise of mixed farming in the tropics and are thus worthy of seriou* 

 experimental attention. 



These conclusions of Prof Cook are of the greatest interest in Ja- 



