CULTURAL CARE. 143 



In certain countries green manures are used. Plants with 

 large roots and well-developed tap roots, capable of gather- 

 ing the ammonia of the air and the mineral matters in the 

 soil should be selected. They generally belong to the- 

 leguminous family : Horse bean, Winter vetch, Clover, and 

 sometimes Winter rape. Some of these plants have the 

 following composition : 



Nitrogen. Pctash. Phosphoric acid. 



Per cent. Per cent. Per cent. 



Vetch 0-56 0'43 0-13 



Rape ... ... 0-46 0'35 0'12 



Clover ... ... 0-42 0'26 0*08 



If we consider the average crop of 4 tons 15 cwt. per 

 acre, when these plants are buried in the ground they 

 furnish the following matters per acre: 



Yield. Nitrogen. Potash. Ph< jgi oric 



Tons cwts. Per cent. Per cent. Per cent. 



Vetch ... ... 4 15 61*92 51 '50 1.V60 



Rape ... ... 4 15 55'20 42'00 14*40 



Clover ... ... 4 15 ol'GO 31'20 9-60 



The above table shows that in case of necessity these 

 manures might be sufficient for small grape crops, but we 

 must not forget that a part of the nitrogen, and all the 

 mineral matters they contain were derived from the soil which 

 they have to fertilize, consequently they may be considered as 

 a means of transforming rather than enriching the soil. 



Soot contains 1*15 per cent, of nitrogen, and has a remark- 

 able effect upon vines planted in calcareous soils. Half to- 

 three-quarters ton is used annually per acre. 



Different chemical manures, containing nitrogen, phos- 

 phoric acid, and potash may be used for completing other 

 manures, or, united in -the required proportions, they may 

 sometimes be sufficient for vine requirements. 



Georges Ville recently recommended the following 

 formula : 



Superphosphate of lime ... ... 352 Ibs. per acre. 



Carbonate of potash ... ... 176 n n 



Sulphate of lime ... ... 352 



It results from what we have already said that the 

 quantities of potash and superphosphate indicated above 

 are too considerable for the requirements of one year 

 (maximum duration of these fertilizers); on the other hand, 

 there is no provision made for nitrogen. An admixture of 

 carbonate of potash and sulphate of lime may be advan- 

 tageously replaced by sulphate of potash. 



