34 



THE AGEICULTUEAL NEWS. 



February 10, 191 i 



•a question of physical environment. There are 

 situations in Trinidad where cacao could be grown 

 very well without shade, just as there are situations in 

 ijrenada where it might be better grown with shade. 

 The principal object is to maintain a high degree of 

 humidity and atmospheric quiescence around the 

 foliage of the cacao. Shade trees help to do this 

 by keeping in the moistitre evaporated from the 

 soil. Shade ■trees act, as well, as a means of keeping 

 down the water-level in the soil owing to the large 

 amount they transpire through their leaves. In these 

 respects shade trees have to be considered in connexion 

 with soil management. 



("omino- now to the cultivation of orchard soils, 

 we notice all over the tropics an extension in the 

 ■employment of the plough and disc-harrow. This is 

 particularly so on coco-nut estates. Writing in con- 

 nexion with coco-nut cultivation in the Federated Malay 

 States. K. W. Munro and L. C. Brown, in their recent 

 book, say: 'As it is a matter of some importance that 

 the soil" generally throughout a plantation should be 

 as friable as possible, to enable the trees to continue in 

 a gojd state of culture, both ploughs and disc-harrows 

 can be utilized for the purpose of continually breaking 

 up the top surface wherever the land is inclined to 

 harden. The beneficial effect this tilling has on 

 the well-being generally is difficult to imagine 

 unless one comes across an estate which is main- 

 tained by this method of cultivation.' In the 

 West Ii.dies the same holds true. On a large coco-nut 

 estate in Nevis, for example, the soil is kept thoroughly 

 cultivated by means of an Averys Working (!ang 

 plough. This plough is drawn by four oxen and works 

 to ii depth of about :5 inches. There is a marked 

 improvement in the appearance of the trees since the 

 plough has been in use. 1 1, also buries weeds and gives 

 the plantation a neater and tidier ap])caranee. 



On cacao estates forking should be practised. This 

 is perioilically done in thvnada, and is held to be one 

 of the factors determining the high yields that charac- 

 terize cacao growing in that island. The practice is 

 being gradually adopted in Trinidad. There is no 

 question as to the great lu netit it exerts: its value is 

 admitted: but the expense and shortage of labour 

 frequently lead to neglect of the practice in some 

 places. 



In an editorial in this.ifowrnal some months ago, 

 we wrote concerning soil aeration; and showed it is 

 probable that on many cacao and coco-nut estates, the 

 trees suffer from there being insufficient air in the soil. 



It was pointed out that the object of drainage is 

 not so much to remove excess of water as to allow of 

 the introduction of air. Drainage in fact would be 

 unnecessary if a water-logged soil could be kept pro- 

 perly aerated by means of air-pumps. It will be 

 realized that ploughing and harrowing help largely to 

 maintain the surface soil in an aerated condition, and 

 this is probably one of the reasons why cultivation 

 exerts such a good influence upon the trees, since the 

 effect is most marked on rather heavy lands especially 

 where the soil is inclined to harden at the surface. 



The last aspects of the scientific management 

 of the soil to which we shall refer are liming and 

 manuring. These are extensive subjects and can only 

 be considered here in the briefest manner. 



Liming is quite distinct from manuring because 

 it maj be done with one or several widely differing 

 ideas. Lime may be applied to improve the physical 

 condition of the soil; it may be applied to neutralize 

 acidity in the soil; it may be applied to increase the 

 availability of other essential plant nutrients: it may 

 be applied to partially sterilize the soil whereby 

 bacterial activity is ultimately rendered more active; 

 and it may be applied in trenches as a fungicide 

 against the spread of root diseases. It may not 

 always be <losirable to bring about these changes 

 in orchard soils but to effect each one of these 

 objects adeijuately, lime must be added in widely 

 differing amounts depending upon the character 

 of any particular soil. Research is now enabling 

 us to state definitely what amount should be applied 

 in any particular case to effect each one of these 

 particular objects. We are gradually beginning to 

 realize better that liming is not one thing but a com- 

 plex, and in the future we shall probably see new and 

 interesting changes in the practice of liming. Results 

 already indicate that it may be unnecessary or even 

 undesirable to apply lime to certain orchard soils with 

 a view to the collection of soil acidity. 



Manuring 

 less complicatei 

 in spite of a 

 express in figur 

 these manures 

 is no doubt tlia: 

 cacao and coc i-i 

 obtained in tla 

 ourable season. 



with the oulinary artificial fertilizers is 



. but it has been found very difficult, 



arge amount of experimentation, to 



s the real benefit gained by applying 



I the soil. Generally speaking there 



he use of artificials pays with limes, 



1 Its, but the maximum benefit is never 



ibsence of good cultivation and a fav- 



Green mulrhing on the other hand almost invari- 

 ably gives sati«:,iction, but like liming its effects upon 



