ia: 



24 CHAPTER III 



work and, on the whole, are fairly good for ordinary farm 

 crops. Eye, maize, potatoes, peanuts and lucerne are among 

 the best crops for these soils. 



(4) Loams. — These are the most useful " all-round " 



soils, combining the lightness and earliness of the sands, with 



the strength and retentiveness of the clays. They are easily 



manipulated, do not readily crush or crack, and are usually 



well supplied with plant-food. Water moves through them 



« freely yet they do not leach badly. Practically all farm crops 



5P thrive satisfactorily on loam soils. They require no special 



!2: treatment, except such attention to good tillage, manuring, 



;3 ^nd the addition of organic matter as is a necessary part of a 



^ good farm practice. 



■^ (5) Clay Loams, Clays and Heavy Clays. — Soils contain- 



c55 ing a high percentage of clay are often worthless for ordinary 



. cropping. However, the lighter types under favourable con- 



^ ditions may be considered to be among the most productive 



of soils. Their characteristic properties are to a great extent 



the reverse of those of sandy soils. Air and moisture move 



slowly through them, the percentage of colloidal matter is 



higher than found in sandy soils, and they are more retentive 



of moisture and plant-food than the lighter types of soil. They 



tend to form surface crusts after rains and on drying-out crack 



badly. The cracking is due to the great shrinkage of the 



gelatinous colloidal matter when drying-out. 



The treatment of a clay soil should be of such a nature 

 that it will remedy the chief defect of this type of soil — viz., 

 heaviness. This may be brought about by green manuring, 

 tillage at the right time, drainage where the soil happens to be 

 waterlogged, and by liming. 



Clay soils are usually rich in plant-food, and plants once 

 established in them thrive well. Grasses and wheat are the 

 most profitable crops on these soils. They are relatively 

 difficult soils to work, because when too wet they puddle 

 readily, and ploughing when too dry results in a cloddy con- 

 dition. When too wet, plants growing in clay soils suffer 

 from poor aeration, and during drought crops suffer pre- 

 maturely. They heat up slowly and are therefore looked upon 

 as cold soils. While sandy soils should be disturbed as little 

 as possible by tillage, clay soils should be worked as often as is 

 economically possible. 



(6) Silt Loams and Silts. — These soils exhibit the same 

 qualities as clay loams and clays, but to a much less marked 



