' 126 



maica, and aie deserving of the most careful consideration, not only in 

 connection with the coffee and cocoa industries, but with other agri- 

 cultural plants in cases where the ground is only partly covered. 



The Blue Mountain Coffee grown from about the elevation of 

 2,500 ft, upwards gets the highest price in the market, and it is pro- 

 duced without any shade. At about 2,600 ft. according as the ground 

 •lopes to various points of the compass, and at all lower bltitudes shade 

 is considered necessary. The tree that is used universally in the Blue 

 Mountains is the West Indian Cedar* The principal reason given 

 for using this particular species is that it dr^ps its leaves during the 

 winter months when coffee requires all the sun it can get, and shade 

 would be injurious. These months are just those that are the dry 

 months of the year. IShade therefore is not necessary at these lower 

 altitudes of the Blue Mountains for the purpose of maintaining a moist 

 atmosphere or for the retention of moisture in the soil. 



Now, although the temperature in the shade is mnch less than that 

 in the sun. Prof. Cook has given samples of coffee doing well in Porto 

 Eico at sea level without shade. 



It appears iherefore that it is the soil that requires shading from the 

 sun, and not the coffee shrub. The temperature of the ground through 

 which the coffee roots penetrate varies with elevation above sea-level, 

 and with amount of shade ; and when we come down from the higher 

 coffee fields to an altitude of 2,500 ft. the ttmperature of the soilthere^ 

 and at lower levels, is possibly greater than the roots of the coffee, or 

 the microbes in the soil, can bear. 



At the Agricultural Conference in Barbados in 1901 in the discus- 

 sion on Mr. Watts' paper on "The treatment of soils in 'orchard' culti- 

 Tation in the tropics,"! the writer of these notes said that "the ex- 

 posure of the soil to the direct rays of the sun causes great injury boih 

 to the soil and the crops growing thereon," and this is the point in the 

 whole subject to which attention should be directed. 



It is known that in a general sense the soil is prepared for plant use 

 by the action of microbes, particularly in the upper layers of the soil. 

 These microbes are enabled to carry on their important work only 

 whilst certain conditions of moisture, air, and tempt rature are suitable. 

 If the temperature for instance is too high, the microbes cannot act, 

 the consequence being that a sufiicient quantity of material is not ab- 

 sorbed by the plants, and the crops produced by the plant are small in 

 quantity 



Mulching which is so beneficial in preventing escape of moisture from 

 the soil, is also of the greatest benefit in shading the soil and so avow- 

 ing the microbes to prepare it for the use of the plant. Mulching 

 certainly does not add ritrogen to the soil as leguminous trees do, but 

 neither does it rob the soil of other necessary ingredients which shade 

 trees of any kind actually do. 



On large estates the difficulty of obtaining large quantities of material 

 for mulching would be great, and probably the best plan to adopt Wduld 

 be to grow some deep rooting leguminous herb, suoh as alfalfa, in 

 spaces between the cocoa, coffee, or orange trees, and to cut it down 



*Cedrela odorata. 



t West Indian Bulletin, Vol. II, 190J, page 96. 



