124 Commercial Gardening 



for the reception of plenty of moisture and its ascent afterwards to the 

 roots of his crops, he must also take care that the supply of moisture does 

 not become exhausted during hot and rainless seasons. The experiment of 

 putting a piece of glass on the surface of the soil to collect the moisture 

 arising from it indicates a way in which moisture may be prevented from 

 escaping into the air from the soil. A piece of board or slate would act 

 in the same way as the glass, although the moisture would not be so 

 apparent. Indeed, layers of almost anything put on the surface of the 

 ground will check the moisture escaping from it freely. The cultivator 

 naturally wishes to keep the moisture in the soil, because it is the only 

 means by which the foods from the soil can be transmitted by root action 

 to all parts of the plant, and because it saves him the labour of watering. 

 Sheets of glass, slates, boards, &c., however, are not the most suitable 

 materials for keeping the moisture in the soil. The grower has found 

 that by placing a layer or mulching of more or less decaying manure on 

 the surface of the soil he not only prevents moisture escaping freely, but 

 he also prevents weeds from growing and robbing him of food and 

 moisture. In addition to this, as the manure gradually decays it yields 

 up to the soil certain valuable foods that are sooner or later washed down 

 to the roots by the rains. The manurial layer also prevents the sun from 

 scorching and baking the soil, and, being a bad conductor of heat, this is 

 a consideration in hot seasons. Layers of short grass, leaves, leaf mould, 

 moss, &c., would act in the same way as the manure. 



When these materials are not available, it is still possible to conserve 

 the moisture by stirring up the surface of the soil to a depth of two or 

 three inches by means of the hoe or scarifier. At first sight it would seem 

 as if breaking up the surface soil would facilitate and accelerate the escape 

 of moisture from the soil beneath. Such, however, is not the case. When 

 the surface is broken up with the hoe a layer of loose soil is then placed 

 over the more consolidated soil beneath. In the latter the moisture is 

 rising freely; but when it comes in contact with the loose layer the particles 

 of soil in it are no longer so closely bound together that the moisture can 

 pass readily to them. Consequently a check to evaporation from the 

 surface takes place, and the moisture is kept in the soil for a longer period. 

 The loosening of the surface soil indeed produces a kind of soil blanket 

 which checks the rapid absorption of heat from the air, and the rapid 

 evaporation of moisture from the soil at the same time. The roots of the 

 crops are therefore kept in a cool, moist, and highly active condition during 

 the hottest seasons. 



In some experiments carried out in America by Professor King on 

 a sandy loam, it was proved that in a hundred days the unmulched soil 

 lost water equal to 6*55 in. of rain, or 655 tons to the acre. When 

 mulched 1 in. deep, the soil only lost water equal to 3'30 in., or 330 tons 

 per acre; at 2 in. deep about 299 tons per acre; at 3 in. 254 tons per acre; 

 and at 4 in. 278 tons per acre. It would thus appear that a mulching 

 or loosening of a soil to a depth of 3 in. gives better results. 



