Vof,. Xlir. No. 321. 



THE AGRICULTURAL NEWS. 



209 



STUDENTS' CORNER. 



Green dressings, other than tho.se of the leguminous 

 kinti, principally benefit the soil owing to the fact that they 

 increase the supply of humus. Tliis subject was (|ue.stione(l 

 up<in in the last issue and the student was asked to give tlu-ee 

 e.xauiples of such crojjs. 



As regards the second (|ue.stio)i concerning tlie chief 

 grasses used in various districts for fodder, the student should 

 refer Ut the A'/ricultural N'eirs iiiv Ai)i\\ 12, 1913, in wliich 

 number the editorial deals with the ini|)rovenient of West 

 Indian pastures and mentions useful annuals like Eragrostis 

 abyssinica (tetl') and Fanicum cofo7i?«/i Ijoth of which occur in 

 the West Indies: also well-know n perennials like Panicum iimx- 

 imuni (Guinea grass), Sporobolus indicus (bed grass), Paspa- 

 lum conju'/atuni (sour grass), Panicum muticum (Para grass), 

 and — most nutritious of all — Andropo'fon caricosus (hay 

 grass). 



Information as to how one 

 would [ilaut out an acre of cleared 

 land in limes can be.st be got 

 from local sources of of informa- 

 tion. In answering a i|uestion 

 the actual practical 



should be describei 



The answei' to the 



albuininoid ratio,' and 



constituents' question 



on 



like this 



operations 



concisely. 



'feed unit, 



'dige.stible 



can be got from text-lxjok; 



agricultural chemistry. 



The fir.st final (juostion which 

 asked for a short essay on the 

 present ])rices of lime prcKlucts 

 otfered scope for showing what 

 th(! various prodiu'ts are and 

 their respective values, and also 

 what knowledge the .student has 

 in regard to the Sicilian source.s 

 of supply. It would also be 

 well to bring into the answer to 

 this ijuestion any facts avail- 

 able concerning the demand in 

 diti'erent places for lime products. 

 What, for instance, is the position 

 in Canada? 



In the last cincstion of all the student was asked what 

 precautions ai-e taken on the estate he is connected with, 

 for the prevention of plant disea.se and insect attack. It 

 should have been luiderstood in api)roaching this question 

 that general principles and information derived from text 

 books will not sutHce. The answer must c<)nsi.st of an account 

 of what is actually l)eing done on the estate the student is 

 acquainted with. It will follow of course, that if no efforts 

 are made to prevent plant disease and insect attack, the 

 question cannot be answered. 



Fio. 4. 



The illustration on this page shows the structure of the 

 underground .system of a stool of sugar-cane. This illustra- 

 tion was puljlished in connexion with an article in the West 

 Indian Bulletin, Vol. X, p. 117, and is intended to show the 

 general rule that the degree (First 8ei-oud, etc.) of any ratoon 

 is not necessarily the same as the degree of the buds (primary, 

 secondary, etc.) of which it is the development. Hence the 



expression 'first rat<}(jn' is sinqjly a popular term to describe 

 the stems which happen to be ripe for reaping two seasons 

 after cuttings have been planted. .In the drawing it will be 

 seen that the first 1 md, or primary bud, did not develop owing 

 to injury, and so the first ratoon crop consisted of no Ijuds of 

 an earlier order than secojidar\- ones. The drawing also shows 

 that the rhizome of the sugar-cane is like (Rh). It is a short, 

 often pear-shaped structure, with very short internodes, and 

 an immense supply of roots. Rhizomes of the cane plant are 

 capable of growth when severed from the parent, being in 

 every way similar to the rhizomes of other plants belonging 

 to the class of monocotyledons, such as ginger, the bandioo 

 and cardamoms. Several other similar rhizomes will be seen 

 in other place.s in the drawing. 



The essential point to realize is that the sugar-cane is 

 naturally an underground plant as regards development, and 

 only .sends up .such aerial parts as are neces.sary to obtain 

 carlion dioxide from the atmosphere. When the bud on 

 a planted cutting begins to develop, the first thing it does 

 is to form a rhizome at its base 

 and to live as an independent 

 plant. It is principally for this 

 reason that circumstantial sup- 

 port is given to the opinion that 

 the fungus Colhlotrichum falca- 

 tum, causing red rot of the sugar- 

 cane, is not transmitted by cut> 

 tings, because the bud can quickly 

 sever itself from infected material 

 and live an independent life. 



It would be well for the 

 student to refer to the Bulletin 

 reference mentioned above, and 

 also to an article on the red 

 °''i-ot of the sugar-cane in the Ai/ri- 

 iidtural Kews, Vol. XII, No. 288. 

 It maj' l;>e further urged that the 

 student himself should dig up 

 a stool of ratoon canes, and 

 endeavour to make out tlie struc- 

 tures which are shown in the 

 drawing on this page. It will be 

 necessary to wash carefully the 

 material, and especially to remove 

 with care the large number of 

 rootlets w h i c h surround the 

 rhizomes and under ordinary conditions prevent their recogni- 

 tion. It may be added that the present time of year is 

 favourable for investigating this matter, and it will well 

 repaj' the trouble involved if the .student carries <.)ut at once 

 the suggestion which is here ]iut forward. 



Questions for Candidates. 



PRELIMINARY QUE.STI0NS. 



(1) Explain the dilfereuce between a i^hysical and chemi- 

 cal analysis of the soil. How would you determine the water 

 holding capacity of a soil? 



(2) Describe how the nitrogen in the air is made avail- 

 alile to plants (a) naturally, (b) artificially. 



INTERMEDIATE QUE.STIONS. 



(1) Write in the form of a diary an account c)f the woi-k 

 on a lime estate during the past month. 



(2) Describe the planting and yields of any three pr(j- 

 vision crops which are early-maturing. What do you know 

 concerning quick-growing strains of the plants you mentiom 



2m Pat. 

 (C4) 



)»2. fi? 



Undekghound System of the Sugar-cane. 



