62 Journal of the Department of Agriculture. 



With regard to the amount of phosphoric oxide to be applied, 

 the case is somewhat different. With the exception of a few rare 

 cases, all our vineyard soils are deficient in this plant-food, most of 

 them very markedly so. Thus we should aim to supply an excess of 

 phosphoric oxide over what the crop requires, in order to grade up 

 the soil in this respect. Further, it seems to be the opinion of 

 certain French authorities that a large amount of phosphoric oxide 

 in the manure insures a good quality of wine, a more regular produc- 

 tion, makes the vines more resistant to disease, and causes the grapes 

 to be of good standard and to ripen well. 



These considerations and a study of the manurial practice of the 

 French viticultural areas led Dr. Perold (''The Manuring of Vine- 

 yards," Union Agricultural Journal, July, 1911), to recommend an 

 application of 120-130 lb. phosphoric oxide per morgen annually. 



Thus we have as our general manurial standard for vineyards- 

 the following, approximately : — 



Nitrogen, 85 lb. ; phosphoric oxide, 120-130 lb. ; potash, 90 lb. 

 per morgen per annum. 



It must be admitted, however, that this standard is somewhat 

 arbitrary. Whether or not the proportions and quantities of the 

 plant-foods are the best and most economical is a matter which can 

 be decided only by experiment, and, unfortunately, our local experi- 

 mental data are very scanty. The proportion of phosphoric oxide to 

 nitrogen and potash is rather low, and it is possible that better 

 results may be obtained by increasing tlie phosphoric oxide still 

 further. In any case there is, of course, liable to be some variation 

 according to the nature and fertility of the particular soil concerned. 

 Farmers who are wine producers on a large scale are strongly advised 

 to obtain their own experimental evidence by carrying out tests as 

 described at the end of this article. 



Manures oe Fertilizers. 



We can now proceed to discuss briefly the various fertilizer 

 materials which are available to the farmer, and which he can use 

 in making mixtures of the required composition. 



In the practice of manuring we must consider the effect upon 

 the mechanical condition of the soil as well as the plant foods added. 

 The use of artificial fertilizers alone year after year is unsatisfactory 

 for several reasons. In the first place it is very costly to maintain 

 fertility in this way, and secondly continued use of artificial 

 fertilizers as a rule does not improve the mechanical condition of the 

 soil; in fact, some of them may have a definite injurious eff'ect upon 

 the soil. Artificial fertilizers generally contain little or no humus 

 (i.e. organic matter), and humus is a most important factor in the 

 problem of keeping up the fertility of the vineyard. If the soil is- 

 inclined to be somewhat heavy, humus helps to open it up, while in 

 the case of light sandy soils it gives body. It also supplies to the 

 vines the most expensive of all plant-foods, nitrogen, in a most 

 economical form. Light coloured soils in particular are in need of 

 humus as a rule. 



The two main ways of adding humus to the vineyard are by- 

 liberal use of kraal or stable manure, and by green manuring. 



