GENERAL HISTORY OF FIELD (^.KMnVINC IJOOTs n:. 



Swedes for four seasons, 1840-Ls:)l>. Larlcy was then ^towii 

 for three years to equalise the soil comlitions, and the pl.H^ 

 were rearranged on substantially the plan they occupy to-day. 

 Swede turnips were grown for fifteen seasons, Ls.lO-iisro, hut 

 it was found impossible to continue the growth of Swedes 

 upon the same land year after year with any success. This 

 was mainly due to the incidental circumstance that on growing 

 the same description of crop, with the same comparatively 

 limited and superficial root-range, for so many years in 

 succession, the surface soil became less easily worked, and the 

 tilth, so important for turnips, was frequently unsatisfactory ; 

 whilst for want of variety and depth of root-range of the crop, 

 a somewhat impervious pan was formed below. After the 

 Swedes sugar-beet followed for five years with the same 

 manures, except that in the last two the nitrogenous manures 

 were omitted, and in 1876 mangels took the place of sugar- 

 beet and have continued ever since. No difHculty has been 

 experienced in growing mangels continuously on the siime 

 land, as may be seen from the fact that the twenty-fifth crop in 

 1900 was the largest of the series. This success nuist be 

 attributed partly to the extended root-range of the mangel, 

 partly also to its freedom from insect and fungoid attacks, 

 which tend to accumulate on land carrying one crop con- 

 tinuously. The only difficulty is experienced on the plots 

 receiving saline manures only, especially where large dressings 

 of nitrate of soda are repeated every year. Owing to the 

 constant removal of organic matter and the injurious action of 

 the saline manures upon the textm'e of the soil the land gets 

 into a bad mechanical condition, veiy sticky when wet, and 

 drying with a hard crust, so nuich so that there is occasionally 

 a complete loss of plant from this ciiuse alone. 



In the Hoos field experiments upon potatoes were begun 

 in 1876, and continued for twenty-six years; they were then 

 discontinued, because the crop on the plots receiving no organic 

 manures had fallen to a very low ebb in consefpicnce of the 

 deterioration of the texture of the soil. But on the jilots 



