112 THE PIILNCIPLES OF 



Evesham, on the lias clay, by many operations, amongst others 

 clay-burning. The late Philip Pusey, one of the greatest 

 agriculturalists that ever lived, was also an advocate of clay- 

 burning. Clay-burning is literally the burning of the staple 

 of the soil ; it is not mere weed-burning, it is not paring and 

 burning. The ground is broken up during the summer, with 

 a strong three or four-horse plough. The clay is then burnt 

 in heaps placed at intervals on the surface. The fire is first 

 kindled by brushwood, roots of trees, and coal where it can 

 be obtained cheaply. The clay is piled upon the fire in large 

 clamps and burnt, and the burnt clay is then spread. Great 

 pains must be taken not to overburn the clay ; it must not 

 be burnt as if intended for a railway embankment or a 

 road foundation nor into clinking, bricklike ashes, but into 

 a black ash or brown clay-coloured ash which will fall 

 readily to powder when rain falls upon it. The clay is much 

 mitigated by the process. Instead of a plastic mass, the 

 particles become repellent to each other, and we introduce 

 sixty to one hundred cubic yards per acre of a loose material 

 which greatly improves the mechanical condition of a clay 

 field. If not overburnt, the soluble matter in the clay is 

 increased, that is to say, the iron, soda, and potash. The 

 amount of soluble phosphoric acid is slightly reduced. One 

 thing we must not forget, that we lose nitrogen and organic 

 matter. These are drawbacks, but on the whole the 

 mechanical or textural improvement, and the increase of 

 soluble potash and iron, account for the favourable results 

 which follow the process. 



We come in the next place to what is called claying ; an 

 operation which may well be grouped with marling, chalking, 

 and the mixing of soils generally. All of-tliese similar oper- 

 ations may be considered together. Sometimes clay, some- 

 times chalk, and sometimes marl or clay are dug and spread 

 on the surface, arid if we have a tract of shifting sand it 



