12 Experiments upon Swedes. 



Plot 5. Manured with 6 cwts. of Superphosphate. 



tons. cwts. qrs. Ibs. 



Produce 21 2 3 12 



Increase 6828 



The superphosphate used in these experiments had the fol- 

 lowing" composition : 



Moisture 10-80' 



"Organic matter 4-21 



Bi-phosphate of lime 20-28 



Equal to bone-earth rendered soluble (31-63) 



Insoluble phosphates 4*11 



Hydrated sulphate of lime (gypsum) 46-63 



Alkaline salts (common salt) 10-78 



Insoluble siliceous matter 3'19 



100-00 



* Containing nitrogen '34 



Equal to ammonia -41 



It will be observed that in this experiment 1 cwt. of this 

 superphosphate gave nearly as much increase as 3 cwts. of the 

 same manure. It would, however, be rash to generalise from this 

 one instance ; nothing less than a dozen experiments in different 

 parts of the field would have warranted the conclusion that on 

 this soil 1 cwt. of superphosphate will give as good a crop of 

 roots as 3 cwts. ; for the fact that the soil is not particularly rich 

 in phosphoric acid renders such a supposition unlikely. More- 

 over, we have a direct evidence in the Experiment No. 5 that 

 the roots were grateful for an abundant supply of phosphates. 

 6 cwts. of the same superphosphate here yielded the heaviest in- 

 crease of all the 20 experimental plots. The superphosphate 

 ued in this experiment was chiefly made from bone-ash, and 

 contained but very little nitrogen. We have thus here another 

 proof that a good crop of roots can be obtained on clay land 

 with superphosphate alone, containing but little nitrogenized or 

 other organic matters. 



Plot 6. Manured with 3 cwts. of Gypsum. 



tons. cwts. qrs. Ibs. 



Produce 16 14 1 4 



Increase 2 000 



The gypsum employed in this experiment was ordinarily good, 

 finely-powdered gypsum, which did not effervesce with an acid, 

 thus proving that it did not contain any carbonate of lime. 



It seems that in this instance gypsum has had unusual effect on 

 the produce. Probably the ashes with which the gypsum was 

 mixed had a share in the increase. 



