Apr. 15. i9i8 Soil Acidity as Influenced by Green Manures 



i«i 



Tables VI and VII give the quantities of nitric nitrogen present in our 

 experimental materials at the second period of observation and the 

 changes in these quantities during the later intervals. The determina- 

 tions began with the 4-week period. 



Table VI. — Nitric nitrogen in manured soils {Series I) 

 [Results expressed as pounds of nitric nitrogen per 2,000.000 ix)unds of soil] 



Material. 



Period 2 

 (4 weeks). 



Period 3 

 (3 months). 



Period 4 

 (s months). 



Period 5 



Period 6 



(7 months). (9 months) 



Average 

 through 



lasts 

 months. 



Control soil 



Legume mixtures: 



Soybean 



Canada field pea . . . 



Sweet clover 



Alfalfa 



Red clover 



Hairy vetch 



Subaverage 



Nonlegume mixtures: 



Wheat 



Rape 



Oats 



Com 



Rye 



Timothy 



Redtop 



Sorrel 



Subaverage 



Barnyard manure mix- 

 ture 



Poultry manure mix- 

 ture" 



Grand average . . 



26. 54 



46. 00 

 51. 10 

 21. 52 

 26.48 

 3-58 

 39-52 



40. 84 



70 



"5 



96 



III 



33 

 58 



40.88 



136. 24 

 127. 02 

 115. 00 

 131.42 

 184. 00 

 105. 10 



57-5° 



136. 98 

 115.00 

 169. 46 

 161. 00 

 184. 00 

 128. 80 



62. 70 



143. 06 



139. 98 

 157-04 

 169. 46 

 246. 00 



140. 32 



45-68 



106. 62 

 109. 80 

 III. 80 

 119.88 

 130. 62 

 94-52 



31-37 



81. II 



133- 13 



149. 21 



149. 



76.36 

 60. 70 

 21. 52 



43 04 



14.36 



2.88 



7.64 



I. 76 



138. GO 



128. 72 

 81.74 

 93.12 

 44. 16 



5-74 

 II. 96 



15-04 



147. 20 

 2 16. 48 

 118.68 

 115. 12 

 58.88 



27-54 

 42.92 

 48.44 



28.53 



65-56 



96.91 



51.06 



53-82 

 176. 64 



79-54 



245- 32 



31-17 



71. 00 



no. 24 



238. 50 

 214. 64 

 134. 18 



153- 32 

 80. 50 

 52.76 

 53-64 

 59.62 



207. 46 



207. 48 



153- 18 



161. 00 



86.98 



64. 40 



68.48 



80. 50 



161. 50 



165. 80 



loi. 86 



114. 12 



56.96 



30. 66 



36.92 



41. 06 



123. 64 



133- 68 



8.61 



84.74 

 214. 64 



107. 32 

 257.60 



75.28 

 223. 40 



131.28 



138. 18 



97.16 



o Omitted from grand average. 



bU>st. 



By reference to the grand average of Table IV, it is seen that, in 

 general, the second 2-week period and that covering the fourth and fifth 

 months were marked by great increases in the lime requirement of most 

 of the manurial mixtures. 



The data for nitric nitrogen exhibit no corresponding increase in the 

 formation of nitrates, or at least in their accumulation, even if we assume 

 that all found at the end of the fourth week were formed in the last 14 

 days of that time, which is not probable. 

 41813°— 18 3 



