rganic matter not required by, 169.

_Nitrobaeter_, 167.

Nitrogen, 115-160;
absorbed by soil, 81, 131;
accumulates in pastures, 134;
in air, 116;
as ammonia in soils, 127;
amount of, in plants, 40;
amount of, in soil, 123;
artificial supply of, 150;
in bat guano, 325;
in bones, 363, 364;
combined, in air, 118;
combined, in rain, 119, 155;
condition of, in manures, 540;
converted into nitrates in soil, 51;
in cow-dung, 226-228;
in cow excrements, 278;
in cow-urine, 230;
difference between surface and subsoil, 126;
different forms of, 45, 116;
dissolved in rain, 131;
in dried blood, 424;
in farmyard manure, 260;
in fish-guano, 321;
fixation of free, 136;
forms of, in plants, 491;
free, relation of, to plant, 117;
gain of, with leguminous crops, 135;
in guanos, 329;
in hoofs and horns, 426;
in horse-dung, 226-228;
in horse-manure, 243;
in horse-urine, 230;
importance of, in soil, 88;
in lean flesh, 424;
in leather, 428;
least abundant of manurial ingredients in soil, 271;
loss of, artificial sources of, 144;
loss of, by crops, 144;
loss of, on farm, 146;
loss of, sources of, 137-150;
loss of, total amount of, 142;
lost in the arts, 148;
lost in free condition, 141;
lost in treating farmyard manure, 146;
lost in milk, 147;
lost by retrogression, 142;
in Manitoba soils, 156;
in meat-guano, 324;
nature of, in soil, 124;
as nitrates in soil, 128;
as nitrates in cropped soils, 130, 157;
as nitrates in Rothamsted soils, 198;
as nitrates in wheat-soils, 157;
in nitrate of soda, 343;
nitric, in soil, 128;
organic, absorbed by plants, 47;
organic, in soil, 125;
original source of, in soil, 133;
in oxen excrements, 280;
in pasture-lands, 158;
peat-soils richest in, 123;
in Peruvian guano, 302, 306, 307, 329;
in pig-dung, 226-227;
position of, in agriculture, 115-160;
relative manurial value of, 556;
Rothamsted experiments on, 115;
in scutch, 427;
in sewage, 431;
in sewage-sludge, 439;
in sheep-dung, 226-228;
in sheep excrements, 280;
in sheep-urine, 230;
in soil, 120;
in soil, portion of, easily nitrifiable, 187;
in soils at various depths, 156;
in soot, 428;
source of, in plants, 15, 16, 40-52;
sources of soil, 131-137;
in straw, 237, 243;
in subsoil,