HORTUS GRAMINEUS WOBURNENSIS. 381 



such lands, by these means, has been increased from one to 

 twelve shillings (their original value) to forty and sixty shillings 

 per acre. But when connected with a breeding flock of sheep, 

 the advantages derived from these meadows are hardly to be esti- 

 mated, for they produce a full bite of grass at least three weeks 

 earlier than the common pastures, and that at a season when 

 every other kind of food is scarce. 



Irrigated meadows seldom or never require any manure, the 

 water being found sufficient to produce that extreme degree of 

 fertility for which they are remarkable.* 



* Sir H. Davy gives the theory of the effects of water in increasing the fertility 

 of meadows. He says they depend on many causes, some chemical, some 

 mechanical : " When land has been covered by water in the winter, or in the 

 beginning of spring, the moisture that has penetrated deep into the soil, and even 

 the subsoil, becomes a source of nourishment to the roots of the plant in summer, 

 and prevents those bad effects that often happen in lands in their natural state, 

 from a long continuance of dry weather. 



" When water used in irrigation has flowed over a calcareous country, it is 

 generally found impregnated with carbonate of lime ; and in this state it tends in 

 many instances to ameliorate the soil. 



" Even in cases where the water used for flooding is pure, and free from vege- 

 table or animal substances, it acts by causing the more equable diffusion of nutritive 

 matter existing in the land; and in very cold seasons it preserves the tender roots 

 and leaves of the grass from being affected by frost. 



" Water is of greater specific gravity at 42 Fahrenheit than at 32, the freezing 

 point ; and hence, in a meadow irrigated in winter, the water immediately in con- 

 tact with the grass is rarely below 40, a degree of temperature not at all preju- 

 dicial to the living organs of plants. 



" In general, those waters which breed the best fish are the best fitted for 

 watering meadows ; but most of the benefits of irrigation may be derived from 

 any kind of water. It is however a general principle, that waters containing 

 ferruginous impregnations, though possessed of fertilizing effects when applied to 

 calcareous soils, are injurious on soils that do not effervesce with acids ; and that 

 calcareous waters, which are known by the earthy deposit they afford when boiled, 

 are of most use on siliceous soils containing no remarkable quantity of carbonate 

 of lime." Agricultural Chemistry, p. 305 et seq. 



The proper business of irrigation begins in October, and is carried on till April, 

 according to circumstances. In cold backward situations it is continued latest, 

 and in warmer soils it is generally finished in February. As soon as the latter- 

 math is eaten bare, the water-carriages are cleared out, and the stops and sluices 

 made good. The water is then admitted on the land, and suffered to remain for 

 two or three weeks, with a dry interval of a day or two; or, according to others, 

 the water is continued on the meadow two -weeks at first, then laid dry for one 

 week, and again laid under water for two weeks more. The state of the grass 

 affords the best rule to judge of the frequency of waterings. It is a general 



