202 Journal of the Department of Agriculture. 



which has become poor or worthless grazing- veld as the result of harsh 

 treatment may then be restored to good pasture. Dr. Sim, in a 

 recent paper on " Soil Erosion and Conservation," rightly points out 

 that vegetation as a preservative covering is protective against 

 (1) isolation, (2) drought, (3) radiation, (4) wind, (5) flood, and 

 (6) donga formation. It is not an extravagant statement that in 

 almost every problem which confronts the South African farmer 

 to-day, the primary cause may be traced back to the native vegeta- 

 tion : it is the starting point at which all investigations must com- 

 mence. 



Now that we are on the road leading to a definite pronouncement 

 on a matter striking to the roots of our pastoral system, we feel sure 

 that the progress of the experiments wnll be followed by our farmers 

 with the greatest interest. These experiments involve a great deal 

 of research and studying of the many factors affecting the 

 subject, and the data collected as the work proceeds will be published 

 from time to time and reference made thereto in the Journal; farmers 

 wishing to study the development of the experiments stage by stage 

 should obtain the publications referred to above and those which will 

 be issued by the Department in the future. It will be understood, 

 however, that a matter requiring so much research and piecing 

 together of evidence will be a lengthy process, and, while the Depart- 

 ment will immediately make known any facts of practical use which 

 its investigations may reveal as the experimental data accumulate, it 

 is likely that considerable time will elapse before the final experiment 

 is carried to a conclusion, when we shall be able definitely to decide 

 upon the treatment of a problem which has remained unsolved for 

 so many years. 



Construction of Earthen Dams. 



The story of irrigation enterprise in South Africa shows how the 

 early methods of flood irrigation in vogue in the Cape Colony have 

 given way to the need of securing a more -secure supply of water 

 during critical seasons of the year, and to-day conservation is the 

 keynote of the Government's policy. In like manner the individual 

 farmer requires his own conservation scheme, a matter of supreme 

 importance and one calling for the consideration of many factors, 

 each of which is essential to the success of the scheme. As a guide to 

 farmers contemplating the construction of earthen dams, we publish 

 in this issue an article on the subject by Mr. I. J. P. Kleyn, C.E., of 

 the Irrigation Department, who, with the help of diagrams, points 

 out the various factors to be observed and describes the progressive 

 processes in the construction of a dam. One of the steps to be taken 

 is, of course, the careful investigation of the proposed site for the 

 reservoir, and it is here, Mr. Kleyn states, that expert advice may 

 become necessary. The Government offers this assistance, and 



application forms may be obtained from the Irrigation Department, 

 Pretoria, for use by any bona fide farmer who requires such assistance. 

 The object of the article is to assist the farmer to a right appreciation 

 of what should be done and much of what should be avoided, and 

 will form a valuable addition to the existing informati^on on a subject 

 of such general interest in South Africa. 



