116 THE PRINCIPLES OF 



then is the season to work and to clean them. The weeds 

 are weak after harvest, their roots run near the surface, the 

 ground can be easily pared, and in the fine September and 

 October days we can burn the weeds. This is also the time 

 to plough clay lands ; the ground being thus exposed to the 

 effect of the winter's frost. One of the finest unpatented 

 tillage implements is frost, and especially is it found useful 

 on heavy classes of clay lands. It gives a pulverized surface 

 much finer than anything man can produce. It is a tilth 

 that will not run together. If a tilth is forced with rollers 

 and clod-crushers, the first heavy rain will cause it to run 

 together like mortar; but a natural tilth produced by the 

 severance of the particles by frost will not run together; 

 it keeps loose. Therefore if we wish to grow roots on clay 

 land we must begin operating in the autumn. Clean it in 

 the autumn, because that is the best time to clean it ; and 

 dung it in the autumn if practicable. Clay land is all the 

 better for plenty of long strawy dung ; every straw rots and 

 leaves a space which facilitates drainage and opens up the 

 clay. Clay soils also possess exceptional powers for retaining 

 fertilizing matter. They will not allow the valuable ingre- 

 dients to wash through them, so that we may safely dung 

 them in the autumn. We then give it a deep ploughing, 

 and the effect of such treatment will be a fine tilth in early 

 spring. If we can drill our rape or our mangolds upon the 

 fine loose mould which is produced by the winter frost, we 

 secure the conditions for the successful growth of roots. 



Another plan for dealing with such soils is to raise them up 

 by means of a double mould-board-plough into ridges twenty- 

 five to twenty-seven inches apart from crown to crown, place 

 dung in the bottom of the trenches, and split the ridges over the 

 dung, leaving what was the centre of the ridge as the hollow. 

 In the spring the ridges will be found to have mellowed 

 down the frost has gone right through them. Then harrow 



