THE NATURE OF SOIL 5 



only does it contain much that is essential food for 

 plant growth, but also it assists the earth in retaining 

 that moisture without which life is impossible. By its 

 chemical activity, also, it produces useful heat, and 

 liberates stores of food from the mineral soil itself. 

 Therefore it is that we add dead leaves, farmyard 

 manure, seaweed and the like to our garden soil. But, 

 though moisture is essential to the health of plants, the 

 presence of stagnant water is little less fatal than 

 drought. If we find that a hole dug in our gardens 

 to the depth of two feet soon contains water not 

 obtained from above, we may usually assume that 

 drainage is required. 



If our soil be too light (Le, sandy) we may improve 

 it by the addition of dried and powdered clay, marl, 

 and organic manure from cowshed or stable : if it be 

 too heavy (^t,e. containing an excess of clay) we may 

 make it more suitable for our garden use by mixing 

 with it sand, ashes, lime, gritty road-scrapings, or old 

 mortar. 



We all know how very much hotter in summer and 

 colder in winter is a starched linen shirt than is one 

 made of flannel or of some cellular open-woven fabric. 

 This is, of course, due to the fact that the former is the 

 better conductor of heat. In like manner, a loose, 

 cellular, open-woven," porous soil is a much worse 

 conductor of heat than the caked and baked soil which 

 we often see in ill-kept gardens. 



The roots of plants like coolness in summer, but in 

 winter they desire all the warmth they can obtain. 

 Hence the desirability of always maintaining the surface 

 of the ground to the depth of an inch or two in a loose, 

 open condition by means of the hoe. This is of value 

 also in checking evaporation, for, by keeping the surface 

 inch of soil loose and fine, the capillary connection be- 

 tween the air and the deeper layers of soil is broken. 



