Experiments upon Sicedes. 163 



7. On comparing the produce of plot X. Avith that of No. XI., 

 it will be seen that 3 cwt. of bone-ash superphosphate produced 

 nearly a ton more roots than a mixture of 6 cwt. of the same 

 superphosphate with 6 cwt. of sulphate of ammonia and 6 cwt. of 

 sulphate of potash. The smaller produce of No. X. either 

 arises from the presence of too large a quantity of soluble saline 

 constituents in this mixture of fertilizing substances, or from an 

 unfavourable action of sulphate of potash. The crop on this 

 plot looked far less healthy than on No. XI. or on No. V. 



In concluding this report of my experiments made in 1856, I 

 may mention tliat I have watched the appearance of the crop on 

 the experimental field succeeding the swedes. This field was 

 sown with barley in 1857. The barley came up well and grew 

 much more luxuriantly on the plots manured the year before with 

 phosphate. Indeed, the difference in the appearance of the plots 

 manured with phosphates and those plots unmanured or dressed 

 with sulphate of ammonia and otlier salts, was so marked in 

 spring, that the most inexperienced observer could single out 

 with the greatest facility the spots upon which superphosphate 

 was applied the year before. I stated my conviction that super- 

 phosphate is often used in much larger quantities than requisite 

 for turnips, but it is consoling to know that a superphosphate, 

 which, like the one employed in my experiments upon turnips, 

 contained nearly the whole of the phosphates in a soluble form, 

 Avhen once incorporated with the soil, remains there ready to 

 benefit not only the crop for the immediate use of which it is 

 used, but also the succeeding crop, especially if that crop is 

 barley. My own observations on the effect upon the succeeding 

 barley of an excess of superphosphate applied to swedes, fully 

 confirm the elaborate and highly important experiments of 

 Messrs. Lawes and Gilbert on the growth of barley. 



Experiments ox Turxips, made in 1857. 

 1. Germination Experiments. 



Having observed in 1856 that the turnips manured with sulphate 

 of ammonia came up much later than those dressed with super- 

 phosphate, and even than the unmanured plots, I was anxious to 

 verify this result by some additional experiments with sulphate 

 of ammonia. It is generally believed that superphosphate pushes 

 (m rapidly the young turnip plant, and as phosphates form a 

 large proportion of the ash of all seeds, it was not unlikely that 

 the effect of a dressing of superphosphate would hasten the ger- 

 mination of the turnip-seed. At the same time, I thought it 

 desirable to submit to experimental proof some other fertilizing 

 matters, with respect to their power of either hastening or retard- 

 ing the germination of turnip-seed ; for it is self-evident that 



M 2 



