A FORTNIGHTLY REVIEW 



LIBRAR 



NEW YOl 

 BOTANIC 



IMPERIAL DEPARTMENT OF AGRICULTURE FOR THE WEST INDIES. uakdb. 



OF THE 



Vol. YH. No. 17.S. 



BARBADOS, DECEMIJEI! 



190S. 



Price \d. 



CONTENTS. 



I'ai ; K. 

 Atmu.spliL'iic- Nitriiguu and 



the Mamifaotiire of 



Calcium Cyaiiauiido... '.V.)S 

 Beet Sut;ai- Product inn in 



Europe .-'.'.US 



Briti.sh (iuiana Industrial 



School -.i'X', 



Broom Corn at Dominica... 3921 

 Cacau Experiment Plots at 



.St. Lucia :W!) 



Cotton Notes : — 

 Cotton Growing at 



Antigua. Address on :VM) 

 Cotton in the Sea Islands S'.MI 

 West Indian Cotton ... .S!»l) 

 Departmental Reports : — 

 Kritisli (iui.in.-i : Board of 



Agriculture, l<.M»7-« ... li'.n 

 Ht. Lucia : Botanic 



Station, etc., l!M)7-8... :-!!t7 



Department News ;-i!)7 



Electricity and the (growth 



of Croi)s 387 



Gleanings '.VMi 



Harrison College. Barbados, 



Agricultural Science 



Exhiliitioiis at 387 



Jamaica, Botanical Expedi- 



tiim to :»_' 



LeguniiucMis Crojis and 



Soil Imjirovement ... .389 

 Maize Breeding in the 



United States 394 



M.-inganese in Subsoil 



Water 399 



P.\GE. 



Market Kejiorts 400 



Notes and Connuents ... ■'->92 

 Nyassaland, Agriculture 



in ... .". 3S)1 



Orange Trade in S]iain ... 388 

 Para Rubl)er Seed, 



(terminating Capacity 



of ". ... ..'. .394 



Phosphate.s in the Soil ... .391 

 Pi])e Calal)ashat St. Luci.a 389 



Renovating Worn-out 



Land. 394 



Rice Re])orL from British 



(Juiana .39."> 



Rubber at St. Lucia ... 393 



St. Lucia, Fruit at .■!88 



St. Vincent, Agricidture 



at 39.5 



Seeds, Rapid Gennin.ation 



of .393 



Students' Comer .39.") 



Sugar Inilustry : — 

 (.|)ueensland's Sugar 



Industry .38(> 



Sugar-cane Ex])eriments 



in liritish (Juiana. ... 38() 

 i^uperphosiihate a7id 



Basic Slag .38.5 



Tobacco, World's Outimt 



of .393 



Trinidad Agricultural 



De]iartmeut 393 



Trinidad, Crown Lands at 392 

 Wefit Indian Products ... 399 



Superphosphate and Basic Slag. 



JKJNCi the phosphatic manures at the dis- 

 posal of the planter, by means of whicli he 

 may return to the soil the phosphoric acid 

 c<j that is with(h-awn in more or less quantity in the 

 j_j production of various agricultural crops, the chief arc 

 ^ superphosphate and basic slag. Other manures that 



form sources of the neccssavy phosph.-ites are dissolved 

 bones, bone meal, and the various guanos. 



Both superphosphate and basic slag consist of 

 phosphoric acid in combination with linie (calcium 

 oxide). It is well known, however, that the two con- 

 stituents are combined in very different proportions in 

 the two maniiies, aiui that as a result they possess 

 somewhat different properties. 



Superphosphate is prepared from insoluble mineral 

 phosphates by treatment with sulphuric acid. As 

 .a result tiie tribasic calcium phosphate (three propor- 

 tions of lime to one of phosphoric acid) is converted 

 into soluble monobasic calcium phosphate (one propor- 

 tion of lime to one of phosphoric acid). Commercial 

 superphosphate is thus a mi.Kture of the soluble calcium 

 phosphate with phosphoric acid, together with gypsum 

 (calcium sulphate), and various impurities derived from, 

 the original mineral. It will be seen that the manure 

 necessarily contains an excess of phosphoric acid. Ordin- 

 ary superphosphate will contain about 26 per cent, 

 of water-soluble phosphates, together with 2-3 per 

 cent, of undissolved phosphate. 



Basic slag is a by-product obtained in the conver- 

 sion of iron into steel, and the phosphoric acid of this- 

 manure originally existed in combination with iron in 

 the ore. Basic slag varies consi<lcrabl3' in (piality, but 

 the phosphoric acid present is usually equal to front 

 3.5 to 40 per cent, of tribasic calcium pho.sjihate. The 

 phosphoric acid does not exist in this latter form, 

 however, being combined with a larger proportion of 

 lime in the form of tetracalcic phosphate, i.e., a phos- 

 phate containing four proportions of lime to one 

 proportion of phosphoric- acid. This tetracalcic phos- 



