86 THE FERTILITY OF THE SOIL [CH. 



CHAPTER VI 



THE CHEQUERED CAREER OF THE CLAYS 



A CLAY soil needs no description. Everyone is 

 familiar with the grey, green or dirty red coloured 

 soil, sticky and slippery after rain, on which in 

 winter time pools of water lie for days or weeks 

 together. In the summer it dries to hard intract- 

 able clods, shrinking so much during the process 

 that great gaping cracks appear, making the fields 

 unsightly and in extreme cases even somewhat 

 dangerous. 



But although its general properties are very 

 characteristic and easily recognisable no one has 

 succeeded in drawing up any rigid definition of what 

 is and what is not a clay soil. No sharp line of 

 demarcation exists in Nature, and the clays shade 

 off by imperceptible gradations into the wholly 

 different class of soils known as the loams. 



Agriculturally the clays are difficult to plough 

 because of their stickiness, and for the same reason 

 they make rather dangerous habitats for seedlings. 

 It is no uncommon experience to have to sow a 

 second time because the first lot of seeds have be- 

 come asphyxiated. Even when the young plants 



