CULTURE WITH LEGUMINOUS TREES. 25 



the movement caused by the wind, it is probable that considerable 

 utility might be found in this idea of shelter planting. Thus at many 

 points in Porto llico the cultivation of coffee is confined to the lower 

 slopes of hills and the sides of narrow ravines, the land above not 

 being utilized, doubtless because too dry to permit a successful begin- 

 ning- with coffee under the prevalent methods of culture. Perhaps it 

 would not be possible to cover all such ridges and higher slopes with 

 coffee, but if the} 7 were planted with leguminous trees or even occupied 

 by ordinary forest growth there can be no doubt that the coffee area 

 could be carried far upward and that the fertility of the plantations 

 would be greatly increased by the materials accumulated above and 

 washed down in readily available solutions. Such tracts of forest, even 

 though of limited extent, also exert an appreciable benefit in retaining 

 water in the soil, so that the advantage commonly ascribed to shade may 

 be secured even from trees planted a considerable distance above. It 

 is not known that the actual value of such an arrangement has been 

 experimentally determined, but when one has opportunity to note the 

 differences between coffee planted below forest and that on entirely 

 denuded ridges or slopes, no doubt of the wisdom of such an arrange- 

 ment will be entertained. 



FALLEN LEAVES AS FERTILIZER. 



Saving in the cost of cultivation through the fact that shade trees 

 discourage the growth of weeds is often advanced as one of the argu- 

 ments for shade culture, notwithstanding the equally obvious fact that 

 shade sufficient^ dense to affect the weeds would as certainly impede 

 the development of the coffee. But notwithstanding this disadvantage, 

 an arrangement under which something may be taken out where nothing- 

 is put in would continue to recommend shade culture to those who have 

 no lack of land or of time, and who are satisfied with small returns. 



Shade culture of a more rational character does, however/ offer an 

 indirect protection against weeds, in that the fallen leaves often cover 

 the ground and largely prevent the lodgment and successful germina- 

 tion of weed seeds. When the slopes are not too steep and the dead 

 leaves lie undisturbed such a leafy covering, or mulch, of the soil may 

 be complete, and unless it becomes so dense as to smother the roots of 

 the coffee the effect may be wholly beneficial, since, as shown by Dr. 

 Delgado 1 the fallen leaves of Erythrina (bucare) and Inga (guama) 



1 Contribuddn al Estudio del Cafe inVenezuela, por Dr. G. Delgado Palacios, Caracas, 

 1895, pp. 93. This author, while defending the use of shade as such, seems to have 

 been the first to realize that the good effects come largely from the fertility imparted 

 to the soil, though he ascribes this result largely to the fallen leaves. The special 

 utility of leguminous trees is emphasized and explained on the ground that, though 

 having superficial roots for the fixation of free nitrogen, they draw nourishment only 

 from the deeper strata of the soil, and thus do not come into harmful competition 

 with the coffee. 



