25 



* 



TABLE OF CONTENTS. 



PAGE 



INTRODUCTION' ; .. 1 



YIELD OF NITROGEN PER ACRE PER ANNUM IN DIFFERENT CROPS, WITHOUT 



NITROGENOUS MANURE (Table!., p. 3, and Table II., p. 5) 2 



YIELD OF NITROGEN IN THE CROPS OF A MANURED ROTATION (Table III., 



p. 7) .. 6 



PERCENTAGE OF NITROGEN IN THE DRY SUBSTANCE OF VARIOUS .CROPS 



(Table IV., p.' 8) 8 



EFFECTS OF NITROGENOUS MANURES IN INCREASING THE PRODUCE OF 



VARIOUS CROPS (Table V., p. 10) 9 



EFFECTS OF NITROGENOUS MANURES ON LEGUMINOUS CROPS (Table VI., p. 



14, Table VIL, p. 17, and Table VIII., p. 19) 13 



GROWTH OF RED CLOVER, YEAR AFTER YEAR, ON RICH GARDEN SOIL 



(Table IX., p. 21, and Table X., p. 23) 20 



PRODUCE OF NITROGEN IN THE MIXED HERBAGE OF GRASS LAND (Table 



XL, p. 25, and Table XII., p. 26) 25 



RED CLOVER GROWN AFTER BEANS (Table XIII., p. 28, and Table XIV., 



p. 29) ... 27 



VARIOUS LEGUMINOUS PLANTS GROWN AFTER RED CLOVER (Table XV., 



p. 32, Table XVI., p. 33, and Table XVII., p. 36) 30 



EXPERIMENTS ON THE NITRIFICATION OF SOILS AND SUB-SOILS ... ... 38 



CAN ROOTS, BY VIRTUE OF THEIR ACID SAP, ATTACK, AND RENDER 



AVAILABLE, THE OTHERWISE INSOLUBLE NlTROGEN OF THE SUB-SOIL ? 41 



ACTION OF DILUTE ORGANIC ACID SOLUTIONS ON THE NITROGEN OF SOILS 



AND SUB-SOILS 41 



EVIDENCE AS TO THE FIXATION OF FREE NITROGEN ... 44 



SUMMARY AND GENERAL CONSIDERATIONS ON THE SOURCES OF THE 



NITROGEN OF OUR CROPS 52 



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