102 
Field Experiments on Swedish Turnips. 
6. And, lastly, it will be seen that precipitated phosphate of 
lime in these experiments produced almost as good a crop of 
swedes as dissolved bones. 
It is hardly necessary for me to say that the results of field 
experiments of a single season are not calculated to settle de- 
finitively the question whether it be more economical, in agri- 
culture, to use dissolved phosphatic materials in the shape of 
superphosphate or to apply them to the land undissolved in a 
finely ground state. 
This spring, the six acres upon which the swede experiments 
were tried in 1880, will be sown with barley, and it is proposed 
to follow the ordinary four course rotation, and carefully to 
weigh the produce, in barley, clover, and wheat. We may, by 
these means, obtain information whether the several manures 
which were used in the swede experiments, will show beneficial 
effects in the succeeding crops. 
I append analyses of the artificial manures and the chalk 
which were used in these experiments. 
Composition of a Sanq^h of Peruvian Guano used in Swede Experiments 
at Woburn. 
Moisture 19-10 
*Oi ganic matter and ammoniacal salts . . . . 36 • 65 
Phosphate of lime 26 "13 
fAlkaline salts 13-32 
Insoluble siliceous matter 4*80 
100-00 
*ContaimEg nitrogen 8-90 
Equal to ammonia 10-81 
fContaining phosphoric acid 4-42 
Equal to tribasic phosphate of lime .. .. 9-G5 
Total percentage of phosphoric acid .. .. lG-39 
Equal to tribasic lohospbate of lime .. .. 35-78 
The Guano was a superior genuine Peruvian Guano. 
Composition of a Sample of finely ground Cambridge Coprolites used in 
the Swede Experiments at Woburn. 
Water and a little organic matter 5-51 
*Phosphoric acid 25 • 70 
Lime 44-18 
Oxide of iron, alumina, magnesia, fluorine,) 25.52 
carbonic acid, &c ) 
Insoluble siliceous matter 8-09 
100-00 
*Equal to tribasic phosphate of lime .. .. 56-11 
