408 JoriJx.vL OF THE Department of Agricultuee. — Nov., 1922. 



The Round Stack. — The round stack should resenihle a rondavel. 

 A stack 6 to 7 yards in diameter will hold about 10,000 bundles. 

 Mark off the g-round, place a bundle on end in the centre, place 

 around this as many bundles as will fit in nicely, leariing' against the 

 centre one with heads slightly above the band, at an angde of about 

 72 deg'rees ; in other words build a shock. Pack round this in the 

 same manner as in a four-sided stack, until you reach the outer 

 circle of your stack, when the butt end of your sheaves should lie 

 flat on the g-round with the head resting on the previous row. This 

 completes your foundation. By placing your outer laj^ers on the 

 bands you will gradually draw in your stack until the summit is 

 reached. For the top or last layers the heads of the sheaves will 

 overlap one another at an angde; that is to say, the ears of each sheaf 

 practically cover the pi-evious one, so that the last .sheaf placed covers 

 all the rest. 



Analyses of Rock Samples from Harding. — In view of the 

 importance of phosphates in South Africa and the search always being 

 made for them, the following results of a fevv analyses of some rock 

 samples received at this Institution from Harding are interesting. 

 The analyses were undertaken to deteiiuine their phosphate content. 

 Their partial composition on a water free basis is given below, and 

 was ascertained l)y the assistant chemist, Mr. J. J. Vogel, M.Sc. 



Sample " A."' Sample " B." Sample " C." 



Insoluble matter SlvU ;«-80 4()-70 



Iron oxide 14-33 12-74 12-47 



Alumina 



Calcium ox ide 



Phosphoric oxide 



Carbon dioxide 



These samples resemble in conjposition some of the Wecnon rocks 

 which are found in a similar geologncal formation. Their phosphate 

 content is low, and their iron oxide and alunnna content twice as great 

 as the lime content. They are of little value commercially on account 

 of their low phosphoric oxide and their high iron content. 



Fertilizing and Manuring of Maize. — Maize, like other plants, 

 takes up a certain amount of mineial plant food from the soil. If 

 the mealie plant is burned to a clean white ash, the minerals, without 

 which the plant will not grow, may be weighed. This ash contains, 

 among other things, phosphates, potash salts, and carbonate of lime. 

 One important substance which the mealie plant takes up from the 

 soil is lost in burning, i.e. nitrogen. 



From the fertility point of view the nitrogen phosphates and 

 potash are the most important of these four. Maize can get along 

 very well with little lime. Seeing that ten bags mealies can take 

 the following amounts of plant food from the soil, it is easy to believe 

 that no soil is inexhaustible, and the average South African soil 

 contains only 1300 lb. of phosphoric oxide per acre in the first 6^/3 

 inches : — 



