HOW HUMOGEN IS APPLIED 171 



humogen two facts have to be borne in mind. The 

 soil must, as in cultivation generally, be open to the 

 air, and its neutral or alkaline condition must be 

 insured by the presence of a sufficiency of lime. As 

 regards the soil texture it is unnecessary to write here, 

 because every farmer and every gardener is fully 

 aware of the importance of having an adequate air- 

 supply for the roots of plants, and recognise why the 

 ordinary methods of good cultivation have to be 

 employed. Experience in the past with nitrobac- 

 terine and with other fertilizers, however, has shown 

 that the necessity of the ground being adequately 

 limed has often not been sufficiently recognized. 



No soil, it has been proved abundantly, can be 

 fertile unless it is free from acidity. In many 

 instances the neutral or alkaline condition of the soil 

 is obtained by general good cultivation and adequate 

 aeration of the soil (see Chapter IX., on the 

 chemistry of the soil). If the land after this treat- 

 ment remains acid, acidity can be removed by 

 dressing with quicklime to the extent of about ton 

 to the acre, or by dressing with air-slacked lime 

 to the extent of about a ton to the acre. The 

 general practice should be to apply the lime in the 

 late winter, or, with heavy clay soils, in the late 

 autumn or early winter. Lime is an essential soil 

 constituent, because it is a plant food, because it 

 renders the potash and phosphates in the soil 

 available to the plants, because it insures the alkaline 

 conditions necessary for bacterial activity, and 

 because of the mechanical effect it produces on soils 

 generally and especially on clays. 



