SOILS. 141 



is especiall.y rich. During the rainy season it is for the most part 

 flooded, but in December it becomes sufficient!}^ dry to admit of cul- 

 tiyation, and yields a harvest of corn at a time when corn can not be 

 orown on hieher and drier land. In the northern part of the island 

 the regions Ivnown as Santa Rosa, Mataguag, and Yigo are famous 

 for the excellence of their products. These regions have been less 

 cultivated than those in the center and south of the island, owing to 

 the fact that there are no sources of water supply for man or animals 

 with the exception of one or two small streams in the immediate 

 vicinity of Mataguag and Santa Rosa, where the platform of porous 

 coralliferous limestone is pierced by volcanic outcrops. An analysis 

 of the best soils of this part of the island shows that they consist 

 largel}^ of heavy reddish clay, and are comparatively rich in nitrates. 

 Where the land is uncultivated it is covered wdth forest growth. 

 When the forest is cleared (PI. XXIII) it is first planted in land taro, 

 bananas, and plantains, and when the stumps are burned and the land 

 sufficiently clean coconuts, cacao, and cofl:'ee are planted. Oranges of 

 excellent quality are produced in the Yigo and Santa Rosa districts, 

 and in sheltered places fine cacao is successfully grown. The coffee 

 of these districts is also of excellent quality. The determination of 

 the water soluble plant food constituents in these soils, which was 

 made by the Bureau of Soils, United States Department of Agricul- 

 ture, shows that they compare very favorabh^ with tropical soils in 

 general. All are relativeh^ high in lime, due to their coral origin. 

 The amounts of potassium in the samples examined are large as com- 

 pared with the soils of the United States, and the large amount of 

 nitrates in the Yigo and Mataguag soils is especially noteworthy, 

 characterizing them as very productive. 



The mesa. — The northern half of the island consists almost entirely 

 of a raised platform of coralliferous limestone called the ''mesa" or 

 "meseta," Its surface is covered with a laj^er of soil often onl}^ a few 

 inches in depth, of a reddish color from the presence of oxide of iron 

 in the decomposing coral of which it largely consists. Beneath the 

 superficial la3'er the subsoil is of rotten coral, and beneath this is a solid 

 mass of the hard coral composing the ancient reef, cemented together 

 by carbonate of lime formed by the action of water upon the oxidized 

 surface limestone. Where the meseta has been cultivated for a long 

 time its productive power is small, and the natives declare it to be 

 "eansada," or tired. Much of the mesa produces excellent tobacco, 

 sweet potatoes, and maize, though no effort is apparently made to fer- 

 tilize it artificially. Abandoned tracts on the mesa soon become over- 

 grown with scrubb}' bushes, including cassia, indigo, sappan wood, 

 and other leguminous plants. The natives understand the economy of 

 allowing them to lie fallow for a period of time sufficient for the 

 undergrowth to form a thicket, and in selecting a tract for planting 



