408 ANNUAL. REPORT OF THE Off. Doc. 



culture, states that lime applied to sucli lands in excess produces an 

 encrustation of the surface that is highly injurious to vegetation, 

 and that is almost impossible to remove, even by deep plowing and 

 heavy manuring with stable and green manures. Patterson(23)found 

 that taking into account the crops for four years after liming, 20 

 bushels gave a more commercial return than GO bushels, and that 

 even 10 bushels gave excellent returns. 



The question of the value of magnesian limes assumed a new in- 

 terest from the investigation® of Loew and May. Most soils give up 

 to strong acid, such as is used in soil analysis, more magnesia than 

 lime; it is not safe to assume from this fact, that the plant will take 

 up more magnesia than lime from such soils. Theoretical considera- 

 tions indicate that magnesian limes, or soils deficient in available 

 magnesia, would be more beneficial than pure lime; that in other 

 cases, the lime present being sufficient to counteract any poisonous 

 action of an excess of magnesium salts in the plant, the substitu- 

 tion of lime by magnesia is a matter of indifference, since most of 

 the chemical functions of lime in the soil can be performed by mag- 

 nesia; while, in a third class of cases, where lime is relatively defi- 

 cient in the soil, even magnesium carbonate might act as a source 

 of poisonous magnesium compounds in the plant, and magnesian 

 lime be therefore inadmissible. Aside from these theoretical con- 

 siderations, based upon relations the farmer has no direct measures 

 of determining, the fact that magnesian limes remain caustic in 

 the soil much longer than pure limes makes greater caution necessary 

 in their use, except when applied to very acid soils; such as old mead- 

 ows and swamps. 



The facts thus set forth establish the truth that lime is a reagent 

 of many uses on the farm, and that its employment can not be gov- 

 (rned by any simple rule. The farmers of other States have exhibit- 

 ed surprise and even amusement at the importance the Pennsylvania 

 farmer attaches to this material, and query why it is needed in Penn- 

 sylvania and not elsewhere. It is probable that some Pennsylvania 

 farmers have overestimated its value as greatly as the farmers of 

 other localities have underestimated it. It is interesting to note in 

 recent times the statement by Wheeler and Tillinghast (24) that its 

 use on the acid granite sands of Rhode Island has resulted in a net 

 profit, in four years, of |27.05 to |62.35, average |45.10 per acre; by 

 Georgeson (25) that lime has greatly improved the acid soils of 

 Alaska; by Burkett (20) that it has given largely increased returns 

 on old meadow land in New Hampshire; and by P. Hillmann (27) that 



(23) Loc. sit. 



(24) Report Rhode Island Exp. Station. 



(25) Bulletin 82, Office of Exp. Station, U. S. Deiit. Agiic. 



(26) Bulletin 59, New HampEhire Agr. Exp. Station. 



(27) Meeth. deutsch. Idw. Gesellsch., 16, 256 seq. 



