6 



gated, but as this manure is seldom dealt with as farmyard manure in 

 this country we need not occupy space in examining it. 



Of the four forms of nitrogen in the dung, that present as albuminoids 

 is extremely slow in its action, and probably but little of it is ever as- 

 similated by plants at all. The other three forms are, however, easily 

 appropriated by plants, the ammonia and nitric acid being of equal value 

 with nitrogen in the form of sulphate of ammonia and nitrate of soda, 

 while the amide nitrogen is also nearly as active. 



The nitrogen in urine is originally, for the most part, in the form 

 of urea, a substance which passes with great rapidity into carbonate 

 of ammonia and is practically as available as sulphate of ammonia, al- 

 though, no doubt, more liable to waste. AVagnor found that at ordinary 

 temperatures the nitrogen in a mixture of urine and water was practi- 

 cally all converted into ammonia in three or four days. The nitrogen in 

 straw is chiefly in the albuminoid form and is of but little value. 



Action of Dung on other Nitrogenous Substances. 



When various samples of pure horse, cow, and ox dung were em- 

 ployed for supplying nitrogen to plants cultivated in pots filled with 

 soil that contained abundance of phosphoric acid and potash, the results 

 were of a most unexpected character. Maercker found in the c.iso of 

 oats that where he applied no nitrogen the yield was 44.82 grammes of 

 grain and straw, and when he added 1.50 grammes of nitrogen in the 

 form of nitrate of soda the produce was 128.37 grammes an increase 

 amounting to 18G per cent. When, however, he used 2.25 grammes 

 of nitrogen derived from two different samples of horse-dung, from cow- 

 dung, an I from ox-dung respectively, the yields were only 35.91, 23.33, 

 41.65, and 4:6.80 grammes. Both samples of horse-dung reduced the 

 yield, in one case by 20 per cent., and in the other by 48 per cent, 

 while in the case of cow dung, the reduction was 7 per cent. Of the 

 four kinds of dung, only that of the ox was capable of increasing 

 the produce, and that to the extent of but four per cent. The 

 apppropriation of nitrogen by the plants was in much the same ratio, in 

 two cases there being slightly more of this element in the yield produced 

 under the influence of dung than when the soil was un:nan jred, while in 

 the other two cases there was less. Maercker repeated this experiment 

 with white mustard, and obtained practically concordant results. With- 

 out any nitrogenous manure he obtained 3.1 grammes of produce, with 

 0.75 gramme of nitrogen in nitrate of soda the yield was 41.3 grammes, 

 while with 2.25 grammes of nitrogen in two samples of horse-dung the 

 yield was only 3.9 and 3.2 grammes, a trifling percentage of the added 

 nitrogen being recovered in one case and none in the other. 



Wagner's experiments were conducted with white mustard, each test, 

 as in Maercker's case, being repeated three times, and the results show 

 great uniformity. Without any nitrogen, beyond what the soil contained 

 the average yield of mustard was 1.6 grammes, while it amounted to 35.6 

 grammes when 2 grammes of nitrogen in the form of nitrate of 

 soda were applied to each pot. Using the same quantity of nitrogen, 

 the yield with cow-dung averaged 0.5 gramme, and with horse-dung, 



