Mineral Manures and Manuring. 
287 
together with the nitrogen of 20 cwts. of haj, caused an increase 
of 24 cwts. of hay and aftermath over the unmanured ph)t. 
The use of dung as a source of nitrogen is unfavourable. 
For every 1 cwt. of hay, only 1^ lb. of nitrogen are needed as 
ammonia-salts, whilst 3'5 lbs. of nitrogen are required in the 
form of dung. In other words, upon pasture-land we use up 
the nitrogen in dung very imperfectly ; scarcely half of it comes 
into operation. This agrees with practical experience, which 
teaches us that dung is far more profitably applied to arable 
land than to pasture. Even in arable land for cereals, and still 
more so for turnips, the nitrogen of dung is never completely 
utilised. This is owing not merely to a deficiency of phosphates, 
but in most cases just as much to a want of potash. Simul- 
taneously with the use of dung, phosphates and potash should 
also be applied. The potash and phosphoric acid mutually 
make each other available, and both combined bring into play 
the full activity of the nitrogen. The amount of nitrogen in 
the dung and soil is really sufficient for larger crops, but the 
quantity of available mineral salts in the dung and the soil is 
not sufficient. Hence, the better the dung, — the greater the 
care which has been bestowed on its management — the less 
favourable is its utilisation, and consequently the more costly 
becomes its production. We cannot, therefore, say that rich 
dung is preferable to poor.* 
Liebig, in his ' Natural Laws of Husbandry,' which work is 
unfortunately little read, and even less understood, has shown 
that the exclusive use of dung without the aid of mineral manures 
must condemn the cultivators of medium and poor soils to con- 
tinuous poverty. In support of this he quotes some experiments 
made in Saxony by Dr. Reuning. Upon soils in Kunersdorf, 
Mausegast and Kotiz 1 cwt. of dung raised the yield of corn 
15*3, 10'7 and 9 "8 lbs. respectively above the yield of the un- 
manured plot. Upon poorer soils in Oberbobritzsch and Ober- 
schonau the increase in yield was only 54 and 5 lbs. Hence 
the good soil realised from the same quantity of dung two or 
three times as much as the bad. On the other hand, an addition 
of 100 lbs. of bone-meal gave an increased yield over the un- 
manured plot in Kunersdorf of 280 lbs., in Kotiz of 40 lbs., and 
in Oberbobritzsch of 19 lbs. of wheat. The poorer soil in 
Oberbobritzsch, therefore, produced from the same quantity of 
phosphoric acid and nitrogen nearly five times as much as the 
naturally richer field in Kotiz. Hence we conclude that the 
large excess of nitrogen in the dung could not be utilised in 
* The views expressed in this paragraph respecting the use of dung are 
contrary to those generally accepted by agricultural authorities in England. 
— F. J. L. 
