208 



THE EOTHAMSTED EXPERIMENTS. 



Table 58 

 explained. 



Intervals 

 between 

 clover 

 crops. 



been fed on the land, in one case 48f , and in the other 47$- 

 bushels. 



Thus, then, the effect on the succeeding barley of the full 

 mineral and nitrogenous manure applied for the preceding 

 turnips is very obvious; whilst the effect on the one hand 

 of the removal of the root-crop, and on the other of the reten- 

 tion on the land of most of its constituents, is also very 

 marked. The experimental results relating to the second 

 crop of the course — the barley — so far fully confirm, there- 

 fore, the explanations which have been given of the beneficial 

 effects of root-crops grown under the ordinary conditions of 

 manuring, on the succeeding cereal grown in alternation 

 with them. 



Examination of the results relating to the quantities of 

 straw, and of total produce (grain and straw together), as 

 given in the middle and lower divisions of the table, will 

 show that they fully bear out the general conclusions that 

 have been drawn from a consideration of the produce of the 



grain alone. 



The Leguminous Crops {or Fallow). 



Table 58 (p. 209) gives for the third element of the typical 

 four-course rotation — the leguminous crops — the results ob- 

 tained in each of the eleven years of the forty-four in which 

 they were grown, in exactly the same form as those previ- 

 ously recorded for the turnips and for the barley. But as in 

 some of the years clover, and in others beans, were grown, 

 the averages are here taken, not for the eight and for the two 

 courses, as with the other crops, but, respectively, for the 

 four years of the eleven in which clover was grown, and for 

 the seven in which beans were grown. 



A glance at the table brings to view some of the difficulties 

 connected with the growth of these crops. Thus, although 

 the scheme of the four-course rotation supposes the growth 

 of red clover as the third crop of each course, that is once in 

 four years, it has in fact only been grown four times in the 

 forty-four years — namely, in the first, seventh, ninth, and 

 tenth courses ; and when it failed beans were grown instead. 

 It is, indeed, a matter of general knowledge and experience, 

 that it is only on a few descriptions of soil that clover can be 

 grown so frequently as every fourth year ; and in many cases 

 it is not attempted to grow it more than once in eight years. 

 The difficulty of growing red clover or beans frequently on 

 ordinary arable land has been very fully illustrated in our 

 experiments on the growth of leguminous crops. On the other 

 hand, it has been found that red clover may be grown for 

 many years in succession on rich garden soil ; and, further, 



