Windbreaks and Shelter Trees 27 



of shade is, at any rate, only a small one in proportion to a well- 

 laid field, and it would be very seldom that a shelter belt would 

 be so accurately East and West as to absolutely keep the sun- 

 light away all day long. The ripening process would not cease, 

 but would only be slightly prolonged. 



These arguments against trees are weak and small when com- 

 pared with the great advantages to be gained. 



(3) Position and Distances. 



The line chosen for a shelter belt will vary in different districts. 

 On the colder farms of Natal, for instance, the Berg winds blow 

 from the West, and to break these winds shelter would be needed 

 on the Western boundaries of the paddocks. In the Eastern 

 Orange Free State the cold winds are generally from the South- 

 East, and the break would need to be on that side. In the Natal 

 Midlands the chief trouble comes from the North-West thunder 

 storms, and the North-Bast and North winds. Here an angle is 

 necessary to protect from both. So one might go on enumerating 

 the need of each locality. But all we need to work upon is the 

 principle which says, " Shut off the worst winds, the prevalent 

 cold or hot or strong winds, wherever they come from." 



It is seldom possible to follow this rule with accuracy, for land 

 contours, shape of " lands,'' aspect of fields -all must needs 

 modify the position. We must just get as near as we can to our 

 objective. 



How far apart should shelter belts be planted, in order to pro- 

 vide for continuous shelter? When the wind reaches a tree belt 

 it goes over it in a fairly abrupt sweep upwards, and descends 

 on the lee-side in a very gradual slope. Scientists have demon- 

 strated that a belt of trees will shelter for a distance, to lee- 

 wards, of ten times their own height. Thus a belt GO feet high 

 would shelter a paddock 200 yards wide. Here then is the limit 

 to the width of the paddock ten times the height when fully 

 grown, of your shelter trees. The length of the paddock or field 

 may be just whatever is convenient, if that length is at right 

 angles to the wind you want to keep out. 



The size of the fields on our farms will eventually be fixed by 

 this rule of shelter. At present they are far too large. Economic 

 farming means small fields, well cultivated, well manured, and 

 well sheltered. 



The width of the belts of trees will vary with circumstances. 

 The man with the small farm will make them as narrow us pos- 

 sible, consistently with effectiveness. But where land is plenti 

 ful, there is no reason why a good broad belt should not be put 

 down. It is probable that the minimum for effectiveness may be 

 taken as a triple line, the centre line being chosen for height, and 

 the outer lines for compactness. Then to ensure compactness, 

 it is necessary to plant at an espacement of 6 feet apart each 

 way, so that the break may become almost impenetrable, when 



