Notes on the Society's Work in 1897-1918. xxxvii. 



At present probably few of the constituents of soils are receiving such 

 intensive investigation as these are. To some agriculturists " humus " 

 appeals as the dominant agent in the fertility of soils ; to others its 

 degradation-products are regarded as most dangerously inimical to 

 crop-production. The probability is that neither of these extreme views 

 is the correct one ; decomposing vegetable-debris is of high importance 

 agriculturally whilst the final degradation-products to which the dark 

 colour of certaiu soils is largely due are, as far as our investigations 

 during the last 21 years show, either practically inert or possibly may be 

 injurious. The productivity of Demerara clay soils certainly is not 

 governed by their proportions of the dark-coloured, alkali-soluble, 

 vegetable decomposition-products to which the term " humus " should be 

 strictly confined, and hence the fact that many of our soils are light- 

 coloured does not supply any justification for the wholesale condemnation, 

 as has been recently done, of our sugar estate managers as being un- 

 scientific, unskilled, unpractical planters. 



In a paper I read in November, 1886 before the Barbados Agricultural 

 Society was the following : — 



" A most important point also, and one which I can 



" scarcely impress upon you too strongly, is the very great mechanical 

 " improvement in the condition of the soil produced by pen manure and 

 " by vegetable green manures, The soils heavily manured with these 

 " become much more retentive of moisture which is a most valuable 

 "property in our climate, whilst the addition of the very large proportion 

 " of organic matter contained in the manures increases the amount of 

 " ' humus ' in the soil ; and, as the activity of the nitrifying organisms 

 " present (both those which oxidise ammonia into nitrates, so preparing 

 " it for plant-food, and those which possibly occasion the assimila- 

 " tion of the free nitrogen of the air) depends in great measure 

 " upou the amount of this substance present, which apparently 

 "acts as food for them, the importance of such increase is evident." 



The earlier parts of this statement are as appropriate now and to this 

 colony as they were in 1886 to Barbados, whilst if for the word "humus '' 

 the words " vegetable debris " are substituted in the latter part this 

 becomes equally applicable, and thus the conclusions stated are of great 

 importance to us at the present time. 



One of the first things which strike a cursory agricultural or scienti- 

 fic visitor here is what appears to be the absence of " humus " on our 

 front lands. Although humus in the strict sense of the term may be pres- 

 ent only in relatively small proportions, yet the far more important plant- 

 debris which do not necessarily darken the soil may be present in some 

 abundance. Such a visitor is apt to explain the light-coloured condition 

 of the soil by an assumption that the planters have by defective methods 

 of cultivation and soil-conservation caused the depletion of the soil in 

 plant-residua. A visit to some newly cleared very fertile river-lauds might 



