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heaping it in parallel ridges a larger surface is exposed 
to the weathering, particularly to the action of frost 
during the winter. The effect of frost is to disintegrate 
the large masses of soil, and so to render the earth more. 
permeable both to water and to air. By exposure to the 
atmosphere moreover the decay of organic matter in the 
soil is promoted, and thereby valuable nutritive matter 
is rendered soluble and available for plant nutrition. It 
is, therefore, sometimes recommended, before ridging, to 
spread any stable manure which is to be incorporated with 
the soil evenly over the plot. A trough is then dug two 
spades wide, one spadeful being deposited to the right 
and the other to the left of the trough. The soil of the 
latter can also be lifted, and turned, or merely forked over. 
This operation of ridging should be commenced in the 
autumn, and can of course only be undertaken on ground 
that is to remain empty during the winter. 
Further information regarding the nature of soils and 
manures can be found in the following excellent books :— 
E. J. RUSSELL. “Lessons on Soil.” Cambridge Nature 
Study Series, 1/-. 
E. J. Russerz. ‘A Students Book on Soils and Manures.” 
Cambridge Farm Institute Series, 1915, 3/6. 
A. D. Harr. “ The Soil.” John Murray, London, 5/-. 
A. D. Hay. “ Fertilizers and Manures.” John Murray, 
London, 5/-. 
