170 



THE GARDENER'S ASSISTANT. 



This manure should be applied in doses of half 

 a pound to each Vine. 



It has long been known that potash plays a 

 very important part in vegetable physiology, in 

 that it serves as a means of enabling starch to 

 move from one part of the plant to another; for 

 instance, from the stem and leaves into the 

 tuber, as in the case of Potatoes. Moreover, 

 those juices of plants which are noticeably sour, 

 such as Lemon-juice, the sap of Rhubarb stalks, 

 and the juice of sour Apples, Gooseberries, 

 Grapes, and the like, commonly contain an acid 

 salt of potash which changes to sugar as the fruit 

 becomes ripe. It was thought by some authori- 

 ties that when Grapes ripen the proportion of 

 potash and phosphoric acid contained in them 

 decreased, and that this was in the ratio in which 

 the sugar increased. 



Nitrate of Potash, commonly called nitre or 

 saltpetre, is a compound of one equivalent of 

 potash with one of nitric acid. Its composition 

 per cent is — potash 46*54, and nitric acid 53*46. 

 It is prepared artificially, in some parts of the 

 Continent, from a mixture of common mould and 

 calcareous earth with animal and vegetable re- 

 mains containing nitrogen. When a heap of 

 these matters is preserved moist in a shaded 

 situation, and moderately exposed to the air, 

 nitric acid is slowly generated ; and this combin- 

 ing with the potash and other bases in the 

 mixture, nitrate of potash and other nitrates are 

 formed. Many composts, doubtless, contain ni- 

 trate of potash formed in this manner, which we 

 use as a manure, though unaware of its presence. 



" A great many rich and fertile soils are found 

 to contain a small quantity of nitrate of potash, 

 soda, or lime, which appears to produce nearly 

 the same effect as the salts of ammonia, render- 

 ing vegetation vigorous and dark-coloured. The 

 May in which these salts are formed will be easily 

 understood when we remember, that whenever 

 substances containing nitrogen decay in the 

 neighbourhood of lime or alkaline salts, a portion 

 of nitric acid is formed. Under these circum- 

 stances, the ammonia which would otherwise be 

 produced is oxidized, and nitric acid and water 

 are formed in place of ammonia; the acid com- 

 bines with the alkali, and nitrate of potash or 

 soda results. These salts are frequently found in 

 mixtures of decomposing organic manures ; they 

 are formed in the same way in the soil itself. 



Nitrate of potash is a powerful manure, con- 

 veying, as we have shown, both nitrogen and 

 potash, and is especially adapted for fruit pro- 

 duction, particularly Grapes, Peaches, and Nec- 

 tarines. It may be applied in solution to French 



Beans in pots, and to Strawberries, also to Sola- 

 nums, Chrysanthemums, and flowering shrubs. 

 Half an ounce to a gallon of water will be ample, 

 given not more often than once a week. 



Nitrate of Soda. — In the case of all the nitrates 

 the nitrogen is actually in a condition in which 

 the plant can take it up at once without change, 

 consequently they are the most rapid in action 

 of all the nitrogenous manures. Nitrate of 

 soda should, therefore, only be applied to the 

 soil when the plant is ready by its root-action 

 to make full use of it, otherwise there will pro- 

 bably be a considerable waste, for nitrates of all 

 kinds are easily washed out of the soil by rain 

 or heavy artificial waterings. 



For out-door crops nitrate of soda should be 

 applied as a top-dressing, either alone or mixed 

 with three times its weight of superphosphate, 

 when the crop is actually established in the soil. 

 Nitrate of soda is particularly suitable for dry 

 seasons, owing to its great solubility, and the 

 fact that no change need take place in it before 

 the plant can assimilate and appropriate it as 

 plant-food. Further, it may be mentioned, that 

 when nitrate of soda is used, an alkali — soda — 

 is liberated which has a decomposing action upon 

 the minerals of the soil. It is, therefore, most 

 important for the gardener to remember, that if 

 the nitrates which are produced in the soil are 

 to be taken up to the greatest advantage by the 

 growing crop, it is particularly necessary that 

 the land be not deficient in any of the mineral or 

 phosphatic constituents which the plant requires. 



Nitrate of soda is obtained from Chili, and is 

 sometimes called Chili saltpetre. About 120,000 

 tons of this manure are annually imported into 

 the United Kingdom. It can usually be obtained 

 of 95-per-cent purity, that is, 95 per cent of 

 actual nitrate of soda, the remaining 5 per cent 

 consisting chiefly of common salt, water, and 

 usually a little sand. Having this composition, 

 nitrate of soda contains about 15 per cent of 

 nitrogen. 



Owing to this large quantity of nitrogen, and 

 the consequent stimulating effect of the manure 

 on a crop or plant, a better result is generally 

 obtained by applying it in small dressings occa- 

 sionally rather than in one large dressing, thus 

 spreading the supply of nitrogen over a longer 

 period, and so exposing the nitrate to less chance 

 of loss by drainage. 



The Effect of Manures. 



Experiments on Peach-trees. — In the State of 

 New Jersey, Somerset County, experiments with 



