58 An Account of the Soil [pt. i 



commonly a period of \dgorous growth. Tliis is well 

 seen in Canada, where a remarkable development of 

 vegetation takes place directly the weather is sufficiently 

 warm. In part the result is due to the effectual cold 

 storage of the plant food, neither loss nor deterioration 

 going on in frozen ground, in part also to the increased 

 activity already mentioned of the food-making bacteria 

 after a spell of adverse conditions. 



Another effect of a wholly different nature is also 

 produced. Frost puffs up or lightens the soil: it splits 

 the hard clods and brings them down to a nice crumbly 

 tilth well adapted for a seed bed. Further, it tends to 

 change clay from the sticky into the crumbly state. On 

 the other hand long continued wetness has the opposite 

 effect : it consolidates the soil, makes it sticky and very 

 unsuitable for seeds. Thus at the end of a mild wet 

 winter the soil is poor in plant food because of the 

 leaching that has gone on, its population of micro- 

 organisms is not highly efficient in making food, and it 

 is in a bad mechanical condition because the wetness 

 has made the clay particles very sticky. On the other 

 hand at the end of a more severe winter when the land 

 lay frostbomid or covered with snow there is a good 

 supply of plant food, all the autumn reserves having 

 been safely locked up in the soil, the micro-organic 

 population has become more efficient in producing plant 

 food through the partial suppression of detrimental 

 organisms, the texture of the soil is very favourable for 

 the production of a good seed bed. The advantages, 

 therefore, are wholly in favour of a dry cold \Wnter, and 

 we can see the wisdom of the old proverbs : 



"Under water famine, under snow bread," 

 "A snow year is a rich year," 



