127
Amount of ammonia in soils 127
Nitrogen present as nitrates in the soil 128
Position of nitric nitrogen in soil 128
Amount of nitrates in the soil 129
Amount of nitrates in fallow soils 129
Amount of nitrates in cropped soils 130
Amount of nitrates in manured wheat-soils 131
The sources of soil-nitrogen 131
Accumulation of soil-nitrogen under natural conditions 133
Accumulation of nitrogen in pastures 134
Gain of nitrogen with leguminous crops 135
The fixation of "free" nitrogen 136
Influence of manures in increasing soil-nitrogen 136
Sources of loss of nitrogen 137
Loss of nitrates by drainage 137
Prevention of loss of nitrogen by permanent pasture and
"catch-cropping" 138
Other conditions diminishing loss of nitrates 139
Amount of loss of nitrogen by drainage 140
Loss of nitrogen in form of "free" nitrogen 141
Total amount of loss of nitrogen 142
Loss of nitrogen by retrogression 142
Artificial sources of loss of nitrogen 144
Amount of nitrogen removed in crops 144
Losses of nitrogen incurred on the farm 146
Loss in treatment of farmyard manure 146
Nitrogen removed in milk 147
Economics of the nitrogen question 147
Loss of nitrogen-compounds in the arts 148
Loss due to use of gunpowder 148
Loss due to sewage disposal 149
Our artificial nitrogen supply 150
Nitrate of soda and sulphate of ammonia 150