290 



TROPICAL AGRICULTURE 



CHAP. 



Weeding. 



Rotation. 



Manuring. 



Returns. 



Successive 

 crops. 



Fodder. 



the vines commence to grow, the ground must be weeded, 

 great care being taken not to injure the foUage of the plants. 

 At the second weeding it may be necessary to mould up the 

 potatoes, if heavy rains have washed down the ridges. Sweet 

 potatoes should not be grown constantly in the same land, 

 but should be rotated with other crops ; and this rule ap- 

 plies to most of the cereals and other food crops, as well as 

 to the cultivation of any plant that does not permanently 

 occupy the soil. This system, which unfortunately is not 

 well understood in the West Indies, is treated of in the first 

 part of the book, under the heading of rotation of crops. 

 In cases, however, where it is necessary to cultivate the same 

 plant continuously on the same land, manuring is absolutely 

 necessary, if the fertility of the soil is to be kept up, and if 

 remunerative returns are hoped for. 



Crops. — Sweet potatoes are usually planted from Sep- 

 tember to May, and crops are gathered in from three to four 

 months from the time of planting. The returns are usually 

 considered to be from four to five tons to the acre when the 

 cultivation is carried on under favourable conditions. After 

 the first crop is dug up, the stems and roots are to be care- 

 fully covered with mould, and a second crop may be ob- 

 tained in a month or two afterwards. Indeed, in rich soil, 

 several successive crops may be gathered from the same 

 plants. The leaves and succulent stems make excellent 

 fodder for the horses and cattle, besides which sheep, goats 

 rabbits and other herbivorous animals are extremely fond 

 of the potato vines. 



Habitat. 



Ancient 

 cultivation 

 of the plant. 



THE TAN I A. Colocasia esculenta. 



Tanias are the tuberous rhizomes of a plant extensively 

 cultivated in most tropical countries. It is a native of 

 India, but it has been grown in Egypt from time immemo- 

 rial, its former botanical name, Colocasia antiquorum^ indi- 



