150 
Field Experiments on Mangolds. 
25, the percentage found in genuine Peruvian guano ; and that 
it yielded not quite 3 per cent, of ammonia, instead of 16 per 
cent., which is the average percentage in good guano. Adding 
together the vi'orthless matters in this feathery compound — for it 
was nothing else but a mixture of a yellow sandy loam with a 
little Peruvian guano and plenty of guano-bird feathers — we 
have no less than 75 per cent, of useless materials, and only 
25 per cent, of fertilising constituents. On inquiry, I find that 
the " feather manure " was sold as Peruvian guano, at 14Z. a ton, 
by a Mr. Weekes, of Bromyard, Herefordshire. Its real value 
cannot be put higher than 21. 10s. or 'SI. at the most. 
Augustus Voelckek. 
VII. — Field Experiments on Mangolds. By Dr. Augustus 
VOELCKEE. 
In laying down a manuring scheme for root-crops, I had mainly 
in view to ascertain, by direct experiments, what influence 
potash exerts on mangolds and swedes when grown on light 
land, and, if possible, to find out in what combinations, with 
other fertilising matters, potash should be employed in a root- 
manure intended for light land in order to produce the most 
beneficial effect. 
For field experiments on root-crops one-twentieth of an acrer 
is a convenient and sufficiently large size for each plot. Each 
experimental one-twentieth of an acre piece should be divided, 
if possible, in such a manner that it will be occupied by 4 rows 
of plants. 
In the following experiments this plan was adopted, and 
the field divided into 11 plots of one-twentieth of an acre each, 
which, as regards manure, were treated as follows : — 
Plot 1 Was left unmanured. 
2 Mineral superphosi)hate . , I65 lbs., or at the rate of 3 cwts. per acre. 
{Mineral superphosphate . . 16 j lbs. „ 3 cwts. „ 
and 
Potash salts 11 lbs. „ 2 cwts. „ 
{Mineral superphosphate . . I65 lbs. „ 3 cwts. „ 
and 
Peruvian guano ., .. 5s lbs. „ Icwt. „ 
5 Peruvian guano .. .. lOa lbs. „ 3 cwts. „ 
6 Left unmanured. 
(Mineral superphosphate .. IGj lbs. „ 3 cwts. „ 
potash salts 11 lbs. „ 2 cwts. „ 
and 
and sulphate of ammonia 5i 11)S. „ Icwt. „ 
