168 



THE GAKDENER'S ASSISTANT. 



position of organic matter in the soil, by which, 

 when thus generated, it is retained. It is like- 

 wise continually formed in the air by the decay 

 of organized bodies, of both animal and vege- 

 table origin. The ammonia existing in the at- 

 mosphere, in the state of a carbonate or nitrate, 

 is soon carried down to the earth by rain and 

 snow, the water of which always contains am- 

 monia and nitric acid. In this way a consider- 

 able amount of nitrogen is supplied to plants. 

 Now, though this quantity of nitrogen might 

 be sufficient to supply the necessary amount of 

 nitrogenous food to plants growing in a state of 

 nature, yet it would prove totally inadequate 

 to meet the greatly increased demand induced 

 by cultivation, and to compensate for the large 

 quantity of nitrogen carried away in the crop. 

 To maintain fertility nitrogenous food must 

 therefore be artificially restored to the soil. 



The beneficial effects of the practice of allow- 

 ing land to lie for a considerable time before it 

 was again cropped were partly due to the gra- 

 dual restoration of nitrogen to the soil by means 

 of rain and other aqueous deposits. 



For the reasons before mentioned, ammonia 

 must be supplied to the soil; this is effected 

 either by the use of organic manures rich in 

 nitrogen, or by employing some of the salts of 

 ammonia. The salts of ammonia which are 

 used for this purpose are the sulphate, muriate, 

 and the phosphate. All these are extremely 

 powerful in their action, and immediate in their 

 effects, requiring at the same time to be em- 

 ployed with great caution. 



Sulphate of ammonia is the salt most com- 

 monly used, and it may be applied at the rate 

 of from 2 to 3 cwts. per acre with perfect safety. 

 If the soil is lacking in available minerals, then 

 an application of superphosphate or potash, or a 

 combination of both, must be added to the am- 

 monia salt. Sulphate of ammonia may likewise 

 be very advantageously employed dissolved in 

 water, as a liquid manure ; and in this way it is 

 peculiarly beneficial to growing plants, whether 

 in pots or in the open ground; especial care 

 should, however, be taken not to use a solution 

 of too great strength. Half an ounce to a gallon 

 of water is ample. 



Potash is an important part of the food of 

 plants, and is found in large quantities in their 

 ashes; yet in most soils it is only found in 

 small quantities in a soluble state; it is conse- 

 quently a valuable constituent of manures. Its 

 salts are found in the excrements of various 

 animals, and in most organic manures. 



Much of the value of wood ashes, as a manure, 



is due to the carbonate and other salts of potash 

 which they contain; and this is confirmed in 

 practice by the beneficial effects which wood 

 ashes produce on Beans, Peas, Potatoes, Tur- 

 nips, and the Vine, which are all plants that 

 contain much potash. 



The value of potash as a manure for Vines is 

 well illustrated by a series of experiments made 

 by M. Ville 1 as far back as 1875, of which we 

 here reproduce the results. The Vines illustrated 

 represent the general average of those grown in 

 each plot of ground. They were taken up and 



Fig 170.— Vines grown without Manure. 



temporarily potted for being photographed. M. 

 Ville grew Vines without any manure for com- 

 parison. On this plot of land two Vines gave 

 only a few shrivelled grapes; in fact the crop 

 might be counted as nothing. 



On the next plot grapes were grown with a 

 manure from which potash only was withheld, 

 and a singular result was obtained, there being 

 no fruit. 



M. Ville says; " In the case of the Potato the 

 suppression of potash manifests itself by a 

 diminution of the crop : with the Vine, however, 

 little or no fruit makes its appearance, and we 

 virtually get no crop at all. The Vine itself 

 barely sends forth two or three feeble shoots, 

 and the few shrivelled leaves are hardly as large 

 as a crown piece, while those of the plants which 



1 Artificial Manures, by M. George Ville, translated and edited 

 by W. Crooks, F.R.S. London: Longmans & Co. (1879). 



