LIME REQUIREMENT OF THE SOIL 



103 



point, the total phosphoric acid in the soils from Plots 4, 6 and 8 

 was determined with the following results : 



1919 



Plot 4 -088 % P 2 O 6 

 6 -052 

 8 -076 



Plot 6 untreated at the beginning of the experiment contained 

 071 % of phosphoric acid. Plots 4 and 8 have each received 800 Ibs. 

 of phosphoric acid during the period of the experiment, sufficient, 

 were there no losses, to raise the soil content of phosphoric acid to 

 107 %. Although the soil samples were removed less than two years 

 after the previous dressing of basic slag had been supplied, it will 



aoo 

 teo 



fxo 



100 

 80 

 60 



40 

 20 



JS 



o 



/ 2 3 4- _. 5 6 7 8 9 



Year 



FIG. 27. Live Weight Gains on Basic Slag and Untreated Plots at Cockle Park. 

 First Period, 1897-1905. Basic Slag Plot (3) . Untreated Plot (6) . 



be noted that the content of phosphoric acid in the soil on Plot 8 

 is little better than at the beginning of the experiment, and that the 

 reserve of phosphoric acid in the soil from Plot 4 is much less than 

 might have been anticipated. If the suggestion that phosphoric acid 

 is still the limiting factor is correct, it would be natural to expect 

 Plot 4 to give superior results to Plot 8. This is in fact the case(i3), 

 and the inferiority of this latter plot over Plot 5 is not due to the 

 depressing effect of lime on the live weight gain, but to the fact that 

 the soil on this particular plot contains a smaller supply of phosphoric 

 acid than on Plot 4. 



If the increase in live weight gain from Plot 3* over Plot 6 at Cockle 

 Park during the period of the experiment is plotted out as is done in 

 * Receives 200 Ibs. of phosphoric acid as Basic Slag every six years. 



