18 Experiments upon Swedes. 



Plots 1 and 2, I think we may safely draw the following conclu- 

 sions from the preceding experiments : 



1. They indicate in the most decided manner the great supe- 

 riority of phosphatic matters as manuring constituents for root- 

 crops. 



2. It would indeed appear that a sufficient quantity of soluble 

 phosphates renders other fertilizing matters superfluous on soils 

 that have a constitution similar to that of the experimental 

 field. 



3. Although ammoniacal salts have had some slight effect 

 when applied alone, they did not appear to exercise any specific 

 action on the turnip-crop. 



4. The experiments leave it undecided whether it is desirable 

 to add ammoniacal salts or nitrates to superphosphate. At the 

 same time they appear to favour the view that on clay soils 

 nitrogenized matters do not increase the efficacy of soluble phos- 

 phate in a turnip-manure, and to confirm my previous observa- 

 tions extending over a number of years. 



5. In this series of experiments nitrate of soda had a decidedly 

 beneficial effect on the turnips. 



In 1860 precisely the same fertilizing matters were used on 

 another field of our farm, and the experiments made in every 

 respect in the same manner as in 1859. An unfavourable season, 

 the turnip-fly, and other casualties, unfortunately spoiled my 

 experiments. I am glad, therefore, that in place of experiments 

 made by myself, I am in a position to communicate a series of 

 experiments which I induced the late Mr. Campbell, of Craigie 

 House, Ayr, to institute in 1860. Mr. J. Russell, steward to the 

 late Mr. Campbell, kindly favoured me with the following 

 tabular statement, showing the quantity and kind of manure 

 employed per acre, its cost, and the produce in clean roots, 

 topped and tailed. (See p. 86.) 



The experimental piece of ground, I am informed, appears to 

 be of equal quality. The soil is considered a rich, light, sandy 

 loam. Each plot was composed of 3 drills, and occupied 2 poles 

 imperial measure. Distance from drill to drill 28 inches. The 

 seed, Skirving's Improved Purple-top Swede, was sown on the 

 18th of May, and the roots taken up on the 22nd of November. 

 The roots grown on the central drill of each plot were carefully 

 freed from dirt, topped and tailed, and weighed. The roots on 

 Plots 1, 2, 3, 11, I am informed, were soon left behind. On 

 Plots 1 and 11, as will be seen, no manure was applied ; and on 

 Plots 2 and 3 sulphate of ammonia only. The produce on ono 

 of the two unmanured portions of the land amounted to 1 ton 

 more than on the other. 



