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EFFECT OF PLOUGHING SOIL WHEN TOO WET OR TOO DRY. 



Sandy soils are usually not injured by handling when wet ; but 

 the case is different with clay soils. A fair quality of brick can 

 be made from any heavy clay soil by working it thoroughly when 

 wet and then drying it in the sun. The effect produced by work- 

 ing wet clay soils is known as puddling. Irrigation ditches in the 

 west are puddled by first flooding them to make them muddy, and 

 then driving bands of sheep along in this mud. This makes the 

 bottom impervious to water and prevents loss from leakage. If a 

 clay soil is ploughed, or even harrowed, when too wet, it is more 

 or less puddled. In this condition it becomes cloddy and imper- 

 vious to air and water. Old roadways that have been thoroughly 

 puddled from traffic in all kinds of weather may be distinguished 

 in fields many years after they have been ploughed up and put 

 into cultivation. 



The proper time to plough land is when it is just moist enough 

 to break up mellow, neither wet enough to leave a slick surface 

 where rubbed by the mouldboard nor dry enough to break up in 

 large clods ; or, as the southern farmer puts it, when the soil has a 

 good season in it. If continued rain follows wet ploughing, little 

 harm follows ; but hot, dry winds would soon leave only a mass of 

 unmanageable clods. In spring and midsummer ploughing, parti- 

 cularly, it is of the utmost importance to run the harrow immedia- 

 tely after the plough. This prevents the formation of clods. 



TERRACING AND SOIL WASHING. 



One of the most serious results that follow shallow ploughing, 

 at least in hilly regions, is the washing away of the soil in torren- 

 tial rains. When terraces are properly laid out they do prevent 

 washing, but they are a very expensive means of accomplishing 

 the end sought. They occupy land that ought to be in crops. 

 They seed the land with weeds. When improperly constructed, 

 and they usually are, they cause great ditches to be washed in the 

 hillsides. Besides this they cut the land up into small, irregular 

 patches and greatly increase the cost of tillage. There is a better 

 way of preventing washing in nearly all cases. 



In the first place, where land has been ploughed only 3 or 4 

 inches deep for several years the subsoil becomes impervious to 

 water and can not absorb a heavy rainfall fast enough to prevent 

 its flowing over the surface. But when the land is ploughed 

 gradually deeper until a good depth of loose soil is obtained, and 

 particularly when an abundance of humus is supplied from grass 

 roots and stubble, or from green crops turned under, or, better 

 still, from barn-yard manure, the soil becomes so porus that the 

 heaviest rains cause little or no flowing of water on the surface. 



IMPROVING THE SOIL. 



We have seen that poverty in soil may be due to poor texture, 



unfavourable structure, lack of humus, deficiencies in the amount, 



form, or proportion of plant food, and to the presence of harmful 



mineral or organic compounds. With the exception of nitrogen, 



