CH. vi] Clay Soils 109 



sowing is difficult and sometimes impossible so that 

 spring crops have to be substituted: the young plants 

 only get through with difficulty and suffer badly in 

 spring: a wet summer is bad and a wet harvest worse. 

 Crops that ought to last a number of years, such as 

 lucerne, only last two or three. If the land is laid down 

 to grass the finer deep rooting grasses never get hold, 

 the plants that survive being the surface rooting Bent 

 grass {Alopecurus pratensis) which withers during dry 

 weather and causes the burnt colour so common on poor 

 clay pastures, the rushes, the coarse file-like Aira cae- 

 spitosa and other plants specially adapted to wet places 

 (Fig. 29). 



The method of deahng with these soils is simple in 

 principle but often difficult in practice: it consists of 

 two parts: (1) arranging a way out for the water by 

 means of a careful drainage scheme and clean ditches; 

 (2) flocculating the clay and taking care that it does not 

 get deflocculated. When this can be done clay soUs be- 

 come very suited for wheat, beans, and, in the southern 

 half of England, mangolds, but more especially they 

 grow good grass so that both meadows and pastures are 

 common. Considerable trouble arises from the fact that 

 plant roots do not develop quickly and that crops do 

 not readily ripen. Now we shall see later that phos- 

 phates have the special effects of inducing good root 

 development and of hastening maturity, and we shall 

 therefore expect that phosphates would prove very 

 beneficial on clay soils. Experiments all over the 

 country show that this expectation is well founded: 

 phosphates have a very considerable effect in improving 

 the productiveness of clay soils. 



The crop most generally suited for clay soil is grass. 



