"Vol. VIII. Xo. 17G. 



THE AGRICULTURAL NEWS. 



2» 



STUDENTS' CORNER. 



Seasonal Notes. 

 JANUARY. 



1st FoKTXKiHT. 



Planters will now be replacing cuttings that have failed 

 i;o grow in the fields of young canes, with, so far as possible, 

 top plants. Note the ditierence in growth of top plants and 

 pieces of cane at this period, as compared with the time 

 when first planted. Planters will be putting finisliing touches 

 to fielrls in which young canes are growing. In the' heavier 

 fields drains will be made to allow the water to run ofi' when 

 the rains come. The later made farmyard manure will also 

 be applied. 



As fast as the cotton ripens it will have to be picked, 

 •care being taken to keep the various qualities separate, and 

 anv cotton that is at all damp should be sunned and suffi- 

 ciently dried before being sent to the factory. Damp cotton, 

 ginned in that condition, usually causes what is known in 

 the trade as ' gin-cut cotton.' 



The bulk of the lime crop has now been harvested, and 

 attention nuist be paid to the condition of the soil. Now 

 is the time to airily \ten manure so as to strengthen the trees 

 for the flowering ])eriod. 



Observe methods of gatliering cacao. What are the 

 reasons for burying cacao shells '! Study changes which take 

 place during fermentation of beans, and note difterence be- 

 tween cacao fermented for several days, and tliat washed and 

 dried at once, the latter being the practice adopted by the 

 peasantry. 



2nli Fortnight. 



On sugar-cane estates, sindlar work to that carried out 

 in the first fortnight of the month will still be in ]irogress. 

 Early cane manure will be appplied towards the end of the 

 month. AVhere }ilanters have field trash to spare, they will, 

 in many instances, use it to mulch thinner jjortions of the 

 fields. 



Branches of cotton plants that have been attacked by 

 the red maggot should be cut off and destroyed. Those 

 planters who have already gathered their first picking of 

 cotton will i>rune oft" any dead wood on the plants. 



In the case of lime trees, note date of appearance rif first 

 blossoms. Observe the time taken from opening of flower to 

 falling of fruit. Commence to remove dead wood. 



Students on cacao estates should make themselves 

 thoroughly acquainted with the construction and working of 

 artificial driers, both ' hot houses,' and the Gordon cacao 

 drier. 



Questions for Candidates. 



I'RELi:\IINARY OIKSTIONS. 



(1) What are the principal elements of plant food, and 

 how does the plant obtain them ? 



(2) What are the principal troublesome weeds in the 

 field.s in your neighbourhood '( Hfiw do weeds injure crops I 



(3) Have you observed anj- connexion between the kinds 

 of soil, and the kinds of weeds which grow on them > Give 

 some facts. 



INTERMEDIATE QUESTION'S. 



(1) Descrilie the principal manures useful as providing 

 potash. 



(2) What manures are used for plant canes and ratoon 

 ■canes respectively ? How are they applied ? 



(3) Describe the curing of cacao, and discuss the value 

 of fermentation in producing a well-cured sample. 



BORDEAUX MIXTURE. 



The eighth report on th(,> work of the Wobum 

 Experiment Fruit Farm, England, deals entirely with 

 insecticides and fungicides, their preparation and uses. 

 Among the investigations carried out at the Station, 

 the results of enquiry into the chemistry of the well- 

 known fungicide Bordeaux mixture has shown how the 

 cost of that substance may be reduced by three-fifths 

 without in any way diminishing its effectiveness. The 

 following is an extract from the rejiort dealing with 

 this subject : — ■ 



The investigation into the nature of the coinpound.5 

 formed by the action of lime on copper sulphate has shov.'u 

 that as many as six ditt'iMent substances may bo present in 

 Bordeaux mixture. The substance which is present when 

 the mixture is made in the ordinary way, by adding excess 

 of lime in the form of milk to copper sulphate, is a double 

 basic sulphate of copper and calcium. The carbonic acid of 

 the air acts on this, forming carbonates and sulphates of the 

 metals, and it is 0A\ing to the gradual re-formation of sulphate 

 of copper HI this way that the mixture possesses fungicidal 

 properties. But the basic sulphate of calcium present is 

 first decomposed before the basic sulphate of copper i.s 

 attacked, so that a certain time always elapses before the 

 mixture b&gins to behave as a fungicide. This is a great 

 disadvantage, but can be obviated by using only just suiii- 

 cient lime to precipitate all the copper in the first instance, 

 for, in that case, a precipitate is formed which contains none 

 of the basic calcium sul])hate. There is, further, a great 

 advantage in thus reducing the lime used, for the basic 

 copper sulphate precipitated is a less basic compound thaiA 

 tliat in ordinary Bordeaux mixture, and it liberates two and 

 a half times as much copper suljihate by the subsequent 

 action of the air ; so that a mixture as efficient as the ordi- 

 nary one may be obtained, ^s'ith the use of only two-fifths of 

 the quantity of copjier sulphate. 



To make this mixture, clear lime-water instead of milk 

 of lime, must be used ; 61b. 6i oz. of copper sulphate are 

 dissolved in water in a wooden pail, and into another large 

 tub of water 2 or 3 tt). of fresh lime are put. After being 

 stii'red several times, and allowed to settle, 86 gallons of the 

 clear lime-water are tapjied off, and mixed with the copper 

 suli>hate, the whole being made up to 100 gallons by the 

 addition of soft water. 



The mixture must always be tested to ma,ko sure 

 that all the copper has been precipitated, and if this i.s 

 not so, a little more lime-water must be addeif, and the 

 te.siing repeated. If the liquid gives no red colour with 

 potassium ferrocyanide it is in a jiroper conditiim for use. 

 The stain jiroduced on a steel knife is often recommended as 

 a test for unprecipitated copper, but it is neither delicate nor 

 safe. Any excess of lime added above the minimum required 

 for the complete precipitation of the copper weakens the 

 mixture, and represents a direct loss of money. The scorch- 

 ing of foliage sometimes noticed after the application of Bor- 

 deaux mixture may be caused by the same substance (the 

 copper sulphate liberated) as that which gives it its fungicidal 

 properties, and if so, such scorching is inevitable ; it is 

 certainly a fallacy to suppose that it can be avoided by 

 u.sing exce.ss of lime : indeed, it is very probable that the 

 scorching often observed is due to the large excess of lime 

 ' used. I 



' 'The mixture made with lime-water as above does not 

 scorch foliage any more than the ordinary mixture, probably 

 less, and has been in constant use in Italy for many year.s. 



