THE AGENTS WHICH AFFECT TLA^: Is 



15 



The mechanical properties or textures of soils are of 

 first concern. No soil that is not open, and easily per- 

 vaded by air and moisture, and comparatively um-etentive 

 of the latter, will ever be fit for growing plants in unless it 

 can be reduced to a better state by art. Stiff and unctuous 

 clays, with close and fatty bog earth, are entirely unsuit- 

 able for the cultivation of plants, until they are thoroughly 

 broken up, and drained, and pulverised, and mixed with 

 lighter ingredients. The mere draining and working of 

 bog soil will do a great deal towards improving its texture. 

 But clays will require long tillage, and the liberal use of 

 such things as coal-ashes, sand, lime and stone rubbish, 

 light manures, or sandy peat, to bring them at all into a 

 good condition. And even with these, much time and pa- 

 tience will be demanded. Throwing them up in ridges 

 during autumn, and leaving them thus till spring, exposed 

 to the action of the winter's frosts, will be greatly con- 

 ducive to their pulverisation. Very light sandy soils, on 

 the other hand, possess faults of texture of an opposite 

 description, though they are much more e?.sily remedied. 

 They give off water too freely, admit air too thoroughly, 

 and become parched and dry in the summer, not being 

 able to sustain any crop whose roots lie near the surface, 

 or any strong-growing kind of plant. Their defects may 

 be corrected by the application of marl and other clays, 

 and by the use of such manures as cow and pig dung. 

 They should never be ridged up in winter, nor turned 

 over more than is really necessary. 



The best kind of soil for garden purposes is a mode- 

 rately strong light-coloured loam, or such an alluvial earth 

 as is produced by deposits from streams and rivers. 

 This will be open, if properly worked, and yet never be- 

 come dried up in ordinary summers. It will possess 

 sufficient substance not to be soon impoverished, and may 

 at any time be got into new " heart " by manure. Chalky 

 soils are often, however, good ; and possess the merit of 

 keeping away many insects. But soils that are gravelly 

 are mostly poor, and easily dried up, and unsatisfactory 

 as to produce, and obstructive of the roots of growing 

 crops. 



The mineral part of the soil, which is composed of clay. 



