THE ESSEX EXPERIMENTS 



23 



tinguished by their darker, reddish, unhealthy appearance ; the treated 

 plots being able to retain their healthy green colour throughout the 

 whole winter. 



TABLE IX. WEIGHT OF HAY AT TYSEA HILL FARM 

 Manures sown: December, 1915 



40 

 30 

 20 

 10 



123456 

 FIG. 1. Yield of Hay (average of 4 years) from the various Phosphate Plots 



at Tysea Hill. Soil Boulder clay. 



1, Untreated. 2, Gafsa rock phosphate. 3, Basic Bessemer slag. 4, Open hearth (fluor- 

 spar) basic slag. 5, Open hearth high sol. basic slag. 6, Open hearth high sol. basic slag. 



