A FORTNIGHTLY REVIEW ^"^«*«^ 



OF THE NEWYO«K 



BOTANICAL 



IMPERIAL DEPARTMENT OF AGRICULTURE FOR THE WEST INDIES. qarde«. 



Vol. VIII. No. 190. 



BARBADOS, AUGUST 7, 1909. 



Peice Id. 



CONTENTS. 



Page. 

 B;u-l)iulos. Produce of ... 25.5 



Book Shulf 254 



Cacao, Mechanical Polish er 



for 244 



Cattle. Selection of for 



Milking Capacity ...250 

 Ceylon, Agricultuial 



Education in ... ... 249 



Ceylon, Copra Exports 



from 248 



Citrus Fruits, Cultivation 



of 248 



Corn, Germination Test 



fur 255 



Cotton Notes:— 



By-products of 24(i 



Exports from Trinidad, 



Grenada and British 



Guiana 24(i 



West Indian Cotton ... 246 

 Disease-resistini; Plants, 



Selection of 249 



Dominica, Land Develop- 

 ment in 247 



Fruits, Packing and 



Sliip])ing of 245 



Fungus Notes 251 



Gleanings 252 



Page. 



Green Dressings and 



Their Application ... 

 Ground Nuts, Selection of 

 Hawaii, The Cocoa-nut in 

 Insect Ni.ites : — 

 New Species of Ceci- 



doniyiidae 



Jute, Possible Substitute 



for 



Katanga, Agriculture in 

 Maize, Diplodia Disease of 



Market Reports 



Mos(iuitos, Simple Trap 



for 



Notes and Comments ... 

 Para Rubber Trees, 



Abnormalities in 

 Porto Rico, Sugar in 

 Seedling Canes, Varia- 

 tion in 



Students' Corner 



Sugar Industry ; — 



Sugar (irowing and 



Manufacture in 



Northern India 



Timber, Preservation of 



Tree-gn iwing Experiment 



Trinidad, Forestry in ... 



241 

 245 

 244 



250 



255 

 25.S 

 242 



25(> 



249 



248 



248 

 249 



249 

 25:^ 



24:^ 

 249 

 247 

 24 ;i 



Green Di-essin^s and Tlieir 

 Application. 



II. THE EFFECT OX THE SOIL. 



N cases where the phmts which are intend- 

 ed to provide green dressings are to be 

 turned into the soil on which they are 

 raised, as is the common practice, the first etfect which 

 has to be considered is that arising from the circum- 

 stance that they have been grown on that soil. 



Under favourable conditions, the burial of plants 

 of any kind will add humus to the soil, thus improving 

 the tilth, with the well-known additional benefit, in 

 the case of legumes, of the increase of its nitrocrenous 

 content. There are instances, however, where the 

 special circumstances surrounding the raising of the 

 crop prevent the acquisition of these benefit-s. In 

 a light, open soil having a small water-holding 

 capacity and liable to suffer from drought, the lowering 

 of the water-content may act so disastrously on the 

 succeeding crop as to make it impossible for it to 

 attain a condition in which it may benefit by the 

 presence of the additional plant food which has been 

 provided for it. Then, too, repeated raising and 

 ploughing-in of green manures on the same soil, as 

 the sole attempt to keep it in condition, will lead to 

 the temporary exhaustion of its mineral constituents, 

 as will be explained later. Thus must the general 

 history of a soil be considered first, when the question 

 of the application of green dressings is under debate 

 and, in the event of a favourable conclusion being 

 arrived at, what follows here is then, and only then, 

 a matter that can have relation to that particular soil. 



Turning, now, to the effects of the buried plants on 

 the soil, the subject may be viewed conveniently from 

 the aspect of the uses of such plants when they are 

 applied in this way. These uses may be grouped under 

 two heads : that of the prevention of the loss of plant- 

 food already present, and that of the provision of 

 additional plant food. 



In the first connexion, it may be remarked that 

 the very important effect of green dressings in prevent- 

 ing the loss of useful soil constituents is very often 

 given much less recognition than it deserves. It is well 

 known that nitrates, owing to their solubility, are very 



