Field Experiments on Swedish Turnips. 
101 
obtained with bone meal on plot 7 a, and also by the smaller 
produce which ground coprolites produced on plot 1 a in com- 
parison with the produce of the duplicate coprolite plot No. 1 b. 
Notwithstanding these and some minor anomalies, arising, 
in my judgment, mainly from the variations in the productive 
powers of the land upon which the experiments were tried, the 
results of the weighings of the experimental swede crop have 
brought to light some interesting facts, to which I desire to 
direct attention. 
1. It will be seen that finely-ground coprolites, and to a still 
larger extent Redonda phosphate reduced to an impalpable 
powder, produced a considerable increase. 
Thus 6J cwts. of ground coprolites on an average gave an 
increase of 3i tons of roots (in round numbers), while 10 cwts. 
of finely-ground Redonda phosphate (phosphate of alumina and 
iron), raised the crop to 5^ tons above the average produce of 
the two unmanured plots. 
2. In the second place, it will be seen that 5 cwts. of dis- 
solved coprolites, costing 22s. Qd., produced nearly twice as 
much increase in clean, topped, and tailed swedes as 65 cwts, 
of finely ground coprolites, costing 22s. 9c?. 
3. On the other hand, the addition of 6^ cwts. of coprolite 
powder to 10 tons of rotten dung produced, if anything, a larger 
increase than the same quantity of dung and 5 cwts. of dissolved 
coprolites. 
4. The large dressing of 20 tons of rotten dung, it will further 
be seen, produced no more roots than 10 tons of dung and 
ground undissolved coprolites, or than 10 tons of dung and 
dissolved coprolites ; and in fact, practically, the average produce 
was the same on the plots 8, 9, and 10. The question may 
therefore be raised whether 10 tons of dung alone, together with 
the phosphoric acid naturally present in the land, may not have 
furnished as much available phosphoric acid as the roots could 
assimilate under the conditions in which the swedes were 
grown, and whether it was any advantage to add either dissolved 
or undissolved coprolites to the dung. 
At any rate, the dung experiments show that the moderate 
dressing of 10 tons of farmyard-manure, with the addition of 
some superphosphate or coprolite-powder, gave as good a crop 
of swedes as the large dose of 20 tons of dung. 
5. The experiments further show that by far the largest 
increase was obtained by means of the mixed manure, composed 
of 3 cwts. of dissolved coprolites and 2^ cwts. of Peruvian 
guano ; and that the expense of this application is much more 
moderate than that of rotten dung, which probably cannot be 
put on the land for much less than 7s. CfZ. a ton. 
