Departmental Activities. 2V6 



It is anticipated that these preliminary experiments will cover a 

 period of a couple of seasons. Subsequently, tiie object will be to 

 determine the following : (a) The quantity and distribution of water 

 that will give maximum yields per acre with the chief forage crops of 

 this area, namely, lucerne, maize (for silage), Sudan grass, mangels, 

 and possibly cowpeas or some other summer annual legume; (b) the 

 quantity and distribution of water to give the maximum yield per inch 

 of water used ; (c) the effect of (1) giving uniform applications of water 

 at fixed intervals of time, (2) watering at different stages in the growth 

 of crops, (3) gradually increasing the quantity of water from early 

 growth until flowering and then gradually decreasing the amount until 

 maturity; (d) the quantity of water required to injure crop growth; 

 (c) other observations will also be made, such as (1) variations in the 

 composition of crops resulting from the use of different irrigations, 

 (2) the effect of large and small quantities of water on the soil composi- 

 tion and on the development of " brak." 



These give some idea of the work to be done, btit do not by any 

 means cover all the problems to be investigated. 



A bird's-eye view of the plots and their surroundings can be 

 obtained from a study of Plate lY, while Plate V shows the storage 

 dam of some 750,000 gallons capacity, which supplies the plots and 

 which, in turn, receives water from an ever-flowing spring. The 

 composition of the water will be determined from time to time. 



Other plots, similar to those already described, are to be brought 

 under canals. They are to be utilized for manurial and rotation, 

 plant pathological and varietal investigations. 



The total area under plots will be, roughly, about 10 acres, made 

 up of some 570 odd l-80th acre plots, all having the dimensions 33 ft. 

 X 16| ft. 



These plots should prove of considerable interest to the public, 

 and Grootfontein visitors should avail themselves of the opportunity 

 of inspecting the work so far as it has gone. 



Stone-lined Reservoirs. — A reservoir was built at Grootfontein a 

 few years ago, the walls being constructed just of earth, 5 feet high, 

 about three feet wide at the top, and about 14 feet wide at the base. 

 The inside of the walls was cobbled with round cobbles, well rammed 

 into the earth, and these were grouted out with cement-mortar to make 

 the wall absolutely water-tight. Later on the height of the walls was 

 increased by 2 feet, and the extra addition of wall also lined with 

 cobbles as before, and water-proofed with cement-mortar. As the 

 reservoir was required very soon after the completion of this addition 

 in height, there was no time to allow the top portion of the wall to 

 settle down properly. Experience now shows that in places where the 

 new earth was not thoroughly rammed, a small crack is formed at the 

 line of junction between the top of the original stone lining and the 

 base of the new lining owing to the settling down of the earth in the 

 new portion of the wall. This should be pointed out as a guide to 

 farmers who may wish to increase the height of an existing dam wall 

 which is lined with stone, the additional height of which is also to be 

 lined. The extent to which earthwork will settle depends on many 

 factors, and greatly on the degree to which the earth has been rammed 

 after depositing, but it is certain that earthwork settles, although 

 sometimes opinions are expressed to the contrary. 



