12 



at least very expensive. Where the lime appears near the surface there 

 is some danger of having too much lime present for the growing of cane. 

 But this difficulty could be overcome by incorporating with it some of 

 the black vegetable mould and thus reducing the danger arising from an 

 excess of lime. Such a mixing has been partially effected in Colonia A, 

 Field No. I ; here the lime is near the surface, and the material resulting 

 from the digging of the ditches was thrown on top of the black soil and 

 mixed with it. The composition of the soil formed in this way was the 

 following : 



Moisture, in fresh state 62.20% 



Moisture, air dry 6.70% 



Insoluble residue ... 2.61% 



Volatile matter 60.58% 



Oxide of iron and alumina ... 1.19% 



Lime 33.02% 



Magnesia 1.98% 



Potash 0.10% 



Phosphoric acid ... 0.07% 



Total Nitrogen 1.91% 



Humus 12.06% 



Humus nitrogen 0.78% 



Humus nitrogen c /c of humus 6.43% 



This is substantially the composition that we would expect to find 

 in a mixture of the black soil and of the marl. 



From the general character of these soils we might conclude that 

 they should after reclamation, and with judicious fertilization and 

 cultural methods be able to produce good crops. Unfortunately there is 

 too little known about tropical soils of this character, to make any offhand 

 recomendations in that direction. British Guiana has large stretches of 

 peaty soils, but there the layer of peat is, according to Noel Deerr, not 

 very thick, and the subsoil consists of a gray clay, poor in lime and with 

 an excess of magnesia over lime. It seems that so far there has been 

 very little need in the tropics of utilizing marsh lands for the cultivation 

 of dry land crops. Most of the experience gained on marsh soils has 

 been gathered in the temperate zone, and we cannot directly apply the 

 results obtained there to our case. A large part of the marsh soils in 

 northern lOurope and in the United States is of an acid character, and 

 in their reclamation it is necessary to apply liberal quantities of lime, 

 usually in the form ot: carbonate, with three purposes in view. In the 

 first place, the calcium carbonate neutralizes the free acids present in 

 the soil; second, it causes ;i rapid decomposition of the partly deca.yed 

 plant remnants, thus bringing about rapid huinification ; and in the third 

 place, it favors the growth of nitrifying organisms and makes the 

 nitrogen available which would otherwise be inert. 



