122 EXPERIMENTS UPON ROOT-CROPS 



root-range of the plant, a satisfactory tilth on some of the 

 plots became so difficult to establish that a good plant rarely 

 resulted. 



Practical Conclusions 



1. The experiments show that Swedes and white turnips 

 cannot be grown repeatedly on the same land, or even at short 

 intervals. 



2. The manuring for Swedes must be liberal, as the yield 

 is much more quickly affected by poverty or exhaustion in 

 the soil than is the case with the other crof)s of the farm. 



3. Although under favourable conditions Swedes can be 

 grown with artificial manures only, yet they are so dependent 

 on a good tilth and on the retention of moisture in the surface 

 soil that the manuring should begin with an application of 

 farmyard manure, unless the land is already in high condition. 



4. Since Swedes grow at a warm time of the year and 

 receive much cultivation of the soil, nitrification is active and 

 the crop does not require a large amount of nitrogenous 

 manure. In the absence of dung, about 2 cwt. per acre of 

 some nitrogenous manure like fish guano or rape dust, together 

 with 1 cwt. per acre of sulphate of ammonia, will be sufficient. 

 When dung is used, the latter only is necessary. For the 

 shallow-rooting Swede crop sulphate of ammonia appears to 

 be a better manure than nitrate of soda. 



5. The phosphatic manuring is most important, and should 

 consist of 3 to 5 cwt. of superphosphate or an equivalent of 

 basic slag in the case of strong soils. Only on the lighter 

 soils will potash be required ; about 3 cwt. of kainit per acre 

 in the winter may then be used. 



III. — Experiments on the Continuous Growth of Potatoes 



ON THE SAME LAND, HOOS FlELD, 1876-1901. 



These experiments were commenced in 1876, and went on 

 for twenty-six seasons until 1901. The varieties grown were 

 — " Rock," four years ; " Champion," eleven years ; " Sutton's 



