470 Abstract Report of Agricultural Discussions. 



even a small portion of soil, especially if it be calcareous, arc cleiirived of 

 this ochrous matter, and become again fit for irrigation ; but in nine 

 cases out of ton it is the sulphate of iron which occurs in waters 

 rising in peaty localities that does the mischief. In the specimens of 

 peaty soil which I exhibit you can see the sulphate of iron crystallizing 

 out. My attention has frequently been directed to the injury caused 

 to vegetation by such waters. A few days ago the He v. Mr. Clutter- 

 buck sent me, from his park near Abingdon, such a sample. Then, 

 again, waters wliich contain too large an amount of saline matters are 

 injm'ious for irrigation. Among these I may mention sea- water, for I 

 could adduce two or three instances in which, to my knowledge, 

 when tried for irrigation, it lias turned out a complete failure, and 

 for two or three years has rendered the soil sterile. 



I promised at the beginning of this lecture to confine my attention to 

 the qualities of waters ; and having mentioned some qualities which are 

 most desirable for irrigation, and others which we ought to avoid, and 

 having further alluded to some waters which are injurious on account 

 of their deleterious substances, I think I have pretty well cxliaustcd 

 the subject. 



Sir John Johnstone, M.P., said that some years ago ho used for the 

 piu'pose of irrigation, water that came from the moors, Avhich proved 

 so deleterious that he was obliged to give up using it. At the time he 

 was under the impression tliat the injury was caused by the tannin in 

 the water ; and he considered it a great advantage that they had in 

 that Society an opportunity of having such mistakes corrected. The 

 mischief was no doubt due to the ochrous matter Avhich the Avatcr 

 deposited in the soil. He wished to add, in confirmation of the 

 Professor's remarks on drainage-water, that he had some meadows in 

 the neighbom-hood of Leominster, where the same water had been used 

 three times, and the last iipplication seemed as successfid as the first. 



In reply to a question from Mr. Frere, 



Professor Voelcker said, — in some of the waters that passed 

 through the primary rocks, the amount of potash is considerable, 

 five or six grains per gallon. That is a larger portion than occurs in 

 sewage. No doubt a great deal of the benefit derived from some 

 natural water is due to the presence of potash. 



The Chair:\ian said Professor Yoelcker's lecture was very valuable, 

 dii-ecting, as it did, the members to the diflerent kinds of water that 

 were most available for irrigation. He agreed with him that hard 

 waters, particularly such as he had seen in the counties of Dorset and 

 Wilts flowing from chalk, were exceedingly valuable. They were, 

 indeed, far more valuable than those soapy and soft waters which some 

 people had supposed to produce the gi-eatcst eftects in irrigation. Tne 

 Professor had wisely separated what he called warped lands — that is, 

 lands on which such deposits were foi-med as came from the K"ile, 

 or might be found in Lincolnshire and some other English counties — 

 from lands to which irrigation was applicable. Irrigation, strictly 

 speaking, consists in the passing of water as rapidly as possible 

 through land without leaving a film behind. He quite concurred Avith 

 the lecturer that where the thinned water of sewage came naturally, if 



