THE ROTHAMSTED EXPERIMENTS 353 



The cropping of the other series is the same, except that fallow 

 cultivation is practiced instead of growing clover or beans the 

 third year. In the tabular statements the one is termed the 

 " legume " system, and the second the " fallow " system. 



Crosswise, Agdell field is divided into three sections of four plots 

 each. One section is unfertilized, the second or middle section 

 received a phosphorus fertilizer for the first nine rotations (36 

 years) and a mixed mineral fertilizer, including phosphorus, po- 

 tassium, magnesium, and sodium, during the last six rotations (24 

 years), while the third section of four plots has received both the 

 mixed minerals and nitrogen during the entire sixty years. The 

 fertilizers are all applied for the turnip crop, that is, only once every 

 four years. 



In each of the three sections two plots (one legume and one fal- 

 low) have had the turnip crops all removed (leaves and roots); 

 while the other two plots (one legume and one fallow) have had the 

 turnips all fed off by sheep, all other crops having been removed 

 from all plots as regularly harvested. In 1904 the plan was adopted 

 of removing the turnips from all of the plots, thus simplifying the 

 experiments as shown in the tables. In 1850, only, clover was 

 grown on the entire field, including the series since in fallow every 

 four years. The twelve individual plots were each one fifth acre 

 in size and nearly square; so that, as conducted since 1904 (or 

 evidently since 1901), the six individual plots are each two fifths 

 acre in size and about twice as long as wide. 



In 1848 Norfolk white turnips were grown on the " legume " 

 series and Swede turnips on the " fallow " series. The exact 

 yields are recorded in Tables 52 and 53; but in computing the 

 average yields for the first twenty years (5 rotations) the 1848 

 yields from the fallow series were used for both series, as otherwise 

 the averages would not be comparable. 



The clover was regularly cut twice during the season (three 

 times in 1874). Undoubtedly the frequent failure of the clover 1 

 crop has to a considerable extent been caused by clover "sickness." 



1 For many years the best farmers of England and Continental Europe have 

 practiced the substitution of some other legume, as beans, yellow trefoil, etc., in 

 alternate rotations, thus seeding clover on the same land only once in about eight 

 years. 



