58 SOILS 



may be ruined for several years by one injudi- 

 cious plowing, when it was too wet. Unless 

 the soil is very tenacious, and "runs together" or 

 "puddles" if left bare over winter, clay land may 

 be fall-plowed to advantage, leaving it rough and 

 exposed to the mellowing action of freezing and 

 thawing. The crust that forms so easily over the 

 surface of clay soil in summer should be prevented 

 by frequent shallow tillage. Something may also 

 be done to improve the texture of clay soils, in 

 certain cases, by liming them. This causes many 

 of the fine grains to stick together, forming larger 

 grains, thereby making the soil looser and more 

 porous. The liming of soils is considered in 

 Chapter XIV. 



CLAY LOAMS 



These are quite similar to clay soils, but they 

 contain less clay and silt, and more sand. A soil 

 carrying 30 to 40 per cent, of clay is generally 

 classed as a clay loam, and a soil carrying 40 to 50 

 per cent, of clay as a heavy clay loam. A clay 

 loam usually has 25 to 35 per cent, of sand, and a 

 heavy clay loam 10 to 25 per cent, of sand. The 

 fair proportion of sand mixed with the clay in this 

 type of soils makes them easier to handle than clay 

 soils, and more porous. They are apt to be rich, 

 especially in potash, not only because of the store 

 of native plant food, but also because they are very 

 retentive soils. The plant food in fertilisers that 

 may be applied to tnem is not quickly leached 

 away, as it is on sandy soils, but is held very 

 tenaciously by this more compact soil. Crops 

 upon clay loams are not likely to suffer from 

 drought as badly as on clay soils, because water 



