Apr. IS, 19T 



8 Soil Acidity as Influenced by Green Manures 



175 



SERIES I: FRESH GREEN MANURES 



For each mixture of the soil with the fresh material (Series I) this 

 theoretical original limestone requirement and the actual requirement 

 determined at the several periods of the experiment are stated in Table 

 III; the amounts and direction of change during the corresponding 

 intervals, in Table IV. 



The figures of Table IV show that all the mixtures exhibited very great 

 differences in limestone requirement from time to time during the nine 

 months through which these observations extended. The degrees of 

 variation significant of real differences, as distinguished from such as are 

 due to difficulties of sampling and analysis, are well established by com- 

 parison of the duplicate determinations made at each period and for 

 each mixture from separate portions of the mixture or soil itself. The 

 average difference between such duplicates corresponded to about 200 

 pounds of limestone per acre. 



Table III. — Limestone requirement of green manures (Series I) 

 [Results expressed as pounds of limestone per 2,000,000 pounds of soil) 



Material. 



Control soil 



Legume mixttires: 



Soy bean 



Canada field pea 



Sweet clover 



Alfalfa 



Red clover 



Hairy vetch 



Subaverage 



Nonlegume mixttires: 



Wheat 



Rape 



Oats 



Com 



Rye 



Timothy 



Redtop 



Sorrel 



Subaverage 



Barnyard-manure mixture 



Grand average 



Original 

 (theoret- 

 ical). 



4,644 



5, 220 



6, 136 



5. 690 

 5,388 

 4,663 

 5,302 



5,400 



4,627 

 5,682 



7,749 

 6,874 

 5,757 

 4,643 

 4,718 



5,733 



5,723 



(?) 



5,584 



Period i 



(2 

 weeks). 



4,644 



3,627 



3,593 

 3,187 

 2,915 

 713 

 2,882 



2,819 



3,492 

 4,305 

 3,525 

 3,932 

 3,254 

 2, 610 

 2,848 

 1,729 



3,187 



3,053 



Period 2 



(4 

 weeks). 



4,711 



4,712 

 4, 104 

 4,949 

 4, 136 

 1,153 

 4,949 



4, 000 



4,644 

 4,949 

 5,051 

 5,457 

 4,543 

 4,271 



4,983 

 2,949 



4, 606 



3,865 3,797 



Period 3 



(3 

 months). 



4,644 



4,678 



4,238 

 4,983 

 3,695 



4,305 



Period 4 



(5 

 months). 



4,677 

 5,661 



5,86s 

 6,509 

 5, 153 

 4,848 



5,865 



3,650 



5,153 

 5,017 

 5,152 

 5,525 

 3,831 

 3,831 

 3,288 



2,237 



4,254 



4,314 3,982 



5,650 



7,594 

 6,068 

 6,068 

 6,544 

 4,958 

 5>3S6 

 4,712 



3,797 



5,637 



4,678 



5,578 



Period s 



(7 

 months). 



4,871 



5,994 

 6, 163 

 6,570 

 5,210 

 5,040 

 6, 062 



5,840 



7,493 

 6,366 



5,892 

 7, 182 

 4,813 

 5,243 

 5,790 

 4,813 



5,949 



5,549 



5,879 



Periods 



(9 

 months). 



4,904 



5,650 

 5,960 

 6, 502 

 4,847 

 4,135 

 4,542 



5,273 



7, 182 

 6,298 

 6,163 

 6,876 



4,508 

 4,847 

 4,474 

 4, lOI 



5,556 



4,575 



5,377 



