144 



THE GARDENER'S ASSISTANT. 



One view which has been advocated is, that 

 broad-leaved plants have the power of taking 

 up combined nitrogen from the atmosphere 

 in a manner, or in a degree, not possessed by 

 the narrow - leaved gramineous plants. The 

 only experiments that we are aware of, made 

 to determine whether plants can take up nitro- 

 gen by their leaves from ammonia supplied to 

 them in the ambient atmosphere, are those of 

 Adolph Mayer in Germany, and of Schlosing in 

 France. Both found that very small quantities 

 of nitrogen were taken up, but both concluded 

 that the action takes place in a very immaterial 

 degree in natural vegetation. It has been 

 found, however, that if a small quantity of 

 guano is placed in water over a hot-water pipe 

 of a greenhouse and allowed to evaporate, that 

 the ammonia gas given off will be absorbed by 

 the foliage of the plants growing therein, and 

 they will assume a dark-green tint. Carbonate 

 of ammonia treated in the same way will have 

 a similar effect. 



It is well known that, under the conditions 

 in which crops are grown in ordinary agri- 

 culture, nitrogenous manures have very direct 

 effects in increasing the produce of Wheat, of 

 Barley and of Oats, of Turnips, of Mangel and 

 of Potatoes. This is the case notwithstanding 

 that in the cereals the increased produce con- 

 sists characteristically of the non-nitrogenous 

 substances starch and cellulose, in the root- 

 crops of the non-nitrogenous substance sugar, 

 and in potatoes of the non-nitrogenous substance 

 starch. Leguminous crops, on the other hand, 

 not only as a rule accumulate much more ni- 

 trogen over a given area of land under equal 

 soil conditions, and contain a higher percentage 

 of nitrogen in their dry substance, than the 

 crops above enumerated, but there is abundant 

 evidence that they also derive much nitrogen 

 from the combined nitrogen of the soil and sub- 

 soil, and further, that they probably take up 

 much as nitric acid; yet it is generally recog- 

 nized in practical agriculture, that direct ni- 

 trogenous manures have comparatively little 

 effect in increasing the produce of such crops. 



As each of the above-mentioned crops has 

 its counterpart in the garden, it will be of 

 interest to show the influence of nitrogenous 

 manures in increasing the production of the 

 non-nitrogenous constituents in those plants. 



As will be seen, the following table shows 

 the estimated amounts of carbon, per acre per 

 annum, in the total produce (grain and straw) 

 of Wheat and of Barley, in the roots of Sugar- 

 beet and of Mangel-wurzel, in the tubers of 



Potatoes, and in the total produce (corn and 

 straw) of Beans, when each is grown by a com- 

 plex mineral manure without nitrogen, and also 

 when grown with the same mineral manure 

 with nitrogenous manures in addition. 



Next is shown the estimated gain of carbon, 

 that is, the increased amount of it accumulated 

 in the crop under the influence of the nitro- 

 genous manures. The estimated increased pro- 

 duction of total carbohydrates, under the in- 

 fluence of nitrogenous manures, is then given; 

 and lastly, the estimated gain of carbohydrates 

 for one pound of nitrogen supplied in manure. 

 Such estimates can obviously be only approxi- 

 mations to the truth; but, accepted as such, 

 they are of interest and of use, as conveying 

 some definite impression of the influence of 

 nitrogenous manures on carbon -assimilation, 

 and on carbohydrate (starchy) formation in 

 plants. 



It will be seen that, independently of the 

 underground growth, the Wheat was estimated 

 to assimilate 988 lbs. of carbon per acre per 

 annum under the influence of a complex mineral 

 manure alone; and that the amount was in- 

 creased to 1590 lbs. by the addition of 43 lbs. 

 of nitrogen as ammonium salts, to 2222 lbs. by 

 86 lbs. of nitrogen as ammonium salts, and to 

 2500 lbs. by 86 lbs. of nitrogen as sodium 

 nitrate. Accordingly, as shown in the second 

 column, the increased assimilation of carbon 

 was, by 43 lbs. of nitrogen as ammonium salts, 

 602 lbs.; by 86 lbs. as ammonium salts, 1234 

 lbs.; and by 86 lbs. as sodium nitrate, 1512 lbs. 



Reckoned in the same way, the increased 

 assimilation of carbon in the Barley was, for 

 43 lbs. of nitrogen as ammonium salts, 950 lbs. 

 per acre ; that is, one-and-a-half times as much 

 as by the same application in the case of Wheat. 



In the Sugar-beet the increased assimilation 

 of carbon, and accumulation of it in the roots, 

 was 1477 lbs. per acre by the application of 86 

 lbs. of nitrogen as ammonium salts, and 1908 

 lbs. by 86 lbs. of nitrogen as sodium nitrate. 

 There was, therefore, more increased assimilation 

 of carbon, and accumulation of it in the roots 

 of the Sugar-beet, than in the grain and straw 

 of Wheat by the same applications of nitrogenous 

 manure. 



In the Mangel-wurzel the increased accumu- 

 lation of carbon in the roots was 1130 lbs. by 

 | 86 lbs. of nitrogen as ammonium salts, and 

 1370 lbs. by 86 lbs. as nitrate; that is, less 

 than in the removed crops of Wheat, and con- 

 siderably less than in the removed crops of 

 Sugar-beet. 



