THE ESSEX EXPERIMENTS 



21 



experienced dries up the heavy soils, and unless the season is particu- 

 larly favourable it is during this month that the growth of the hay 

 crop is checked. The western part of the county has the benefit of 

 from -6 to -8 inch more rain during this month. Moreover the boulder 

 clay, although a heavy soil, is not nearly so heavy as the London 

 clay and does not 'cap' and crack so badly as the London clay 

 during dry and warm spells of weather. 



DETAILS OF EXPERIMENTS 



The plots were all one-quarter of an acre in area, with the exception 

 of those at Tysea Hill Farm, which were one-fifth of an acre. Three 

 types of basic slag have been used. Basic Bessemer slag, basic open 

 hearth slag without the addition of fluorspar, and basic open hearth 

 slag with the addition of fluorspar. These basic slags have been com- 

 pared with the following rock phosphates: Florida pebble, Florida 

 soft, Tunisian, Algerian, Gafsa, Egyptian, Cambridge coprolites, and 

 a ferruginous Cleveland phosphate. The composition of these phos- 

 phates is given in Table VIII. A more detailed analysis of many of 

 these materials has been published elsewhere (4, 20). At two of the 



TABLE VIII. PARTIAL ANALYSIS OF THE PHOSPHATES USED IN THE 



FIELD EXPERIMENTS 



