140 MANUAL OF MODERN VITICULTURE. 



3RD. MANURING OR FERTILIZING. 



(A.) MANURING. 



Vines require nitrogen, phosphoric acid, and potash. The 

 two first matters seem to influence the vegetation only, the 

 third seems to promote the production of sugar in the fruit. 

 All manures containing these three matters in suitable 

 preparations, and in a sufficiently assimilable state, may be 

 used. 



According to Miintz, the following are the quantities cor- 

 responding to a yield of '1,056 gallons per acre in -the 

 Mediterranean regions : 



Nitrogen ... ... ... .. 121 Ibs. 



Potash ... ... ... ... 110 // 



Phosphoric acid ... ... ... 88 // 



Vine-growers should, therefore, try to furnish their vines 

 annually with the above-mentioned quantities of these ferti- 

 lizers unless the soil already contains one or more of them 

 accumulated in large quantities. A chemical analysis of the 

 soil is necessary to ascertain if this is the case. 



Deherain considers that phosphoric acid will give iiseful 

 results 1st, in soils containing less than O'OOl of total 

 phosphoric acid ; 2nd, in those containing O'OOl of phos- 

 phoric acid and only 0*0002 of acid soluble in acetic acid ; 

 3rd, in those containing less than 440 Ibs. per acre of phos- 

 phoric acid soluble in tartaric acid. 



Paul de Gasparin considers that potassic manure does not 

 give good results in soils containing more than 1'25 per cent, 

 of potash. An analysis of the soil is not always sufficient 

 to indicate the matters which have to be added to it. When 

 these are not in an easily assimilable form, they may, 

 although existing in large quantities, have no action on the 

 vegetation, and require the addition of the same matters in 

 a more readily assimilable form. 



Cultural experiments are necessary to ascertain these facts. 

 The vineyard to be studied should be divided into plots in 

 squares containing about 100 stumps each, sufficiently far 

 apart for the fertilizers of one square not to influence another. 

 One is used as a check, and does not receive any fertilizer ; 

 another receives a complete manure containing sufficient 

 quantities of nitrogen, potash, and phosphoric acid to replace; 



