HORTICULTURAL LABOURS ON T11E SOIL. 227 



CHAPTER III. 



OPERATIONS OF HORTICULTURE. 



THE operations of Horticulture are very numerous, but they may be all 

 included under operations in which strength and mechanical skill are chiefly 

 required in the operator ; those which imply a considerable degree of know- 

 ledge of vegetable physiology ; those in which to a knowledge of plants and 

 their culture requires to be added some acquaintance with the principles of 

 design and taste ; and those in which is required a knowledge of the general 

 principles of business. The first may be called Horticultural Labours ; the 

 second, Operations of Culture ; the third, Operations of Horticultural Design 

 and Taste ; and the fourth, Operations of General Management. 



SECT. I. Horticultural Labours. 



530. Labours differ from operations in being of a coarser and commoner 

 kind, and hence requiring but a small portion of that skill which may be 

 strictly considered as professional : they are, in short, such as every person 

 living in the country ought to be able to perform, either as a matter of 

 business, as in the case of the working man ; or as a matter of recreation, as 

 in the case of a man of wealth or leisure. All mechanical labours may be 

 resolved into the elementary movements of lifting, carrying, drawing, and 

 pushing ; and in whichever way these are combined, or to whichever imple- 

 ments they are applied, the result will depend on the quantity of matter in 

 the implement, and the rapidity or motion with which it is lifted, carried, 

 drawn, or pushed. 



SUBSECT. I. Horticultural Labours on the Soil. 



531. Object of labours on the soil. Before any labour on the soil is com- 

 menced, the labourer, or his director, ought to bear in mind the relations of 

 the soil to heat, air, and moisture, as laid down in Part I., chap. ii. The 

 objects for which the soil is laboured are, pulverization, to render it more 

 readily penetrated by the roots of plants, and by heat, air, moisture, and 

 sometimes by frost ; to allow superfluous moisture to escape into the subsoil ; 

 to mix the upper and lower parts of the upper stratum of soil together ; to 

 mix the coarser and finer parts together; to add or mix in earths or 

 manure ; to free the soil from root or perennial weeds, stones, or other ob- 

 jects unfavourable for culture ; and to destroy surface or annual weeds. The 

 grand sources of heat to soil are the sun and the atmosphere, including rain 

 at a higher temperature than the soil ; and the sources of cold, or of the 

 abstraction of heat are, rain at a lower temperature than the soil, frost, snow, 

 ice, and where draining has been neglected, subterraneous water. The 

 greatest degree of cold produced by these causes, excepting the last, will 

 always be found on the surface of the soil, and the best mode of supplying 

 the heat that has been abstracted will be by leaving the surface to the action 

 of the sun and of the air. By digging or trenching down a cold surface heat 

 is abstracted from the soil, the natural temperature of which will in that 

 case be lowered ; and thus a plant grown in a soil so treated, will be, in so far 

 as bottom heat is concerned, worse than if it were in a state of nature, in 

 which heat abstracted by the air is always restored by it The average tem- 

 perature of the surface soil in most countries is believed to be nearly the 



