162 Journal of the Department of AitRicitlture. 



EXPERIMENTS AND INVESTIGATIONS. 



Work at the Schools of Agriculture and Experiment 

 Stations and Sub-Stations. 



[A review of the research and imestigational work being carried out by the various Divis^ioiis 

 of the Department of Agriculture appeared in the April, 1920, number of the J«vrnal. 

 — AcTixfi Editor.] 



I.— AT CE13ARA, NATAL. 



liOTATlOiV MaNUKIAL ExrERTMEXT. 



At the School of Ag-riculture, Cedara, Natal, an investigatiou is in 

 progress to determine which is the better farming- practice nnder 

 Xatal conditions (a) the continued use of quickly available phosphates 

 such as superphosphate, (h) the use of insoluble pliosphates. It is 

 generally recog'nized that superphosphate gives a larger and more 

 immediate return when compared with other phosphatic manures, but 

 the question it is desired to settle is whether continued use of this 

 manure is a sound practice when carried on for a considerable term of 

 years. In order to test this, land has been chosen which has hitherto 

 never l)een fertilized and which has recently been broken up. Two 

 areas have been chosen, one for treatment with the readily available 

 forms of phosphoric acid, and the other for the insoluble form such 

 as vSaldanha Bay ])l)osphate. These manures are not being- used 

 alone, but limed plots (slaked lime) are being- tried out with the 

 superphosphate plots and ground limestone plots along with the 

 insoluble phos})l)ate plots. Manure of the same value year by year is 

 lieing api>lied, and the exi)eriment is designed to rnn for a number of 

 ye-trs. The land is being cropped under a rotation system, which 



IS 



Maize — First year. 



Maize — Second year. 



Teff— Tliird year. 



Cowpeas and Soya Beans — Fourth year. 



After a number of years data will be available to i)rove M-hether 

 (n) or (6) is the better farming practice. A system of per- 

 manent agriculture should aim at the gradual betterment of the soils 

 of the farm, and not their depletion. The use of superphosphate on 

 soils of the red doleritic type is open to question as to its being good 

 practice. There are considerable data to prove that the residual 

 value of superphosphate on such soils is practically n/7, the unused- 

 phosphate reverting into iron or aluminium phosphate, very insoluble 

 forms in the soil, and so i)assing beyond the power of the plant 

 immediate! v to attack. 



