ACTION OF FARMYARD MANURE ON SOILS. 49 



2. That the proportion in which these three ingredi- 



ents are present is not the best proportion for 

 the requirements of crops. 



3. That the form in which a portion of these ingredi- 



ents nitrogen and phosphoric acid is present 



is not of the most valuable kind. 

 It is consequently not as a direct chemical manure 

 that farmyard manure is pre-eminently valuable. We 

 must seek for perhaps its most valuable properties in 

 its indirect influence. 



1. It adds to the soil a large quantity of organic 

 matter. Most soils are improved by the addition of 

 humus. The water-absorbing and retaining powers of 

 a soil are increased by this addition of humus, while it 

 enables the soil to attract an increased amount of mois- 

 ture from the air. This is often of great importance, as 

 in the period of germination of seed. 1 The influence 

 it exerts on the texture of the soil in the process of 

 fermentation is also very great. This is especially so 

 in soils whose texture is too close, such as heavy clayey 

 soils. It opens up their pores to the air, and renders 

 them more friable. Where such an influence is most 

 required, as in clayey soils, the manure ought to be 

 applied in a fresh condition, so that tlie maximum 

 influence exerted by the manure in this direction 

 may be experienced. On light soils, on the contrary, 



1 See paper on "Mammal Experiments with Turnips" by author, 

 in Journal of Highland and Agricultural Society of Scotland, 

 1891. 



I) 



