,66 BOARD OF AGRICULTURE. 



water that runs over it quietly to glide off." But though not 

 so nutritive as grass growing in the natural moisture, it is 

 probably not so much less nutritive as many would suppose. 



Stiff soils are generally sufficiently moist without irrigating, 

 and light soils are more suited to this treatment. Sandy and 

 gravelly soils, with a porous subsoil, are greatly benefited 

 by it. 



River water is most frequently used for these purposes, 

 though spring water may be used to great advantage ; and mud- 

 dy streams, containing a large amount of animal or vegetable 

 matter, are always eminently suitable for the purposes of irri- 

 gation. 



But the value of irrigation does not depend solely upon the 

 supplies of moisture which it furnishes. " The mechanical 

 action of the irrigatory current of water, in exercising the 

 plants, strengthening their organism, keeping their stems and 

 root crowns clear of obstruction, promoting the equable circu- 

 lation of water and oxygen around them, and causing an equa- 

 ble distribution of the soluble materials of their food, probably 

 plays a considerable part in irrigatory fertilization. The 

 differences of effect, from the mere circumstance of fluence or 

 stagnation in the water, are prodigious ; for while flowing water 

 coaxes up the finest indigenous grasses of the climate, and ren- 

 ders them sweet and wholesome, and nutritious and luxuriant, 

 stagnant water starves, deteriorates, or kills all the good 

 grasses." 



The process of surface irrigation is not so simple as many 

 would suppose. It requires great skill and practice, and the 

 farmer who attempts it without sufficient consideration is very 

 apt to fail. In cases where it is thought to be practicable, it 

 should be tried* at first only as an experiment, and not on so 

 large a scale as to involve great expense, unless there is a rea- 

 sonable prospect of permanent advantage. With respect to 

 its advantages, Sir John Sinclair says, "First, with the excep- 

 tion of warping, it is by far the easiest, cheapest, and most 

 certain mode of improving poor land in particular, if it is of a 

 dry and gravelly nature: second, land, when oner improved by 

 irrigation, is put into a state of perpetual fertility, without any 

 occasion for manure, or trouble of weeding, or any other ma- 



