GROUND LIMESTONE AS A FERTILISER.

Globe, Volume XXIV, Issue 2683, 13 November 1882, Page 3

GROUND LIMESTONE AS A FERTILISER.

The following letter from W. H. Jordan, Prof, of Agriculture in the Penua. State College, to “J. C. P.,” Alleghany Co., discusses the subject of ground limestone as a fertiliser, and with his consent we publish it:— Two facts can bo stated which will probably help you in settling this matter of the use of ground limestone. First — Neither caustic lime (burnt) nor ground limestone is a fertiliser proper. The latter is mainly carbonate of lime, and the former is mostly lime, the carbonic acid having been driven off by heat. It would be a rare case where it would be necessary to add either lime or limestone to supply lime for the use of plants. Both substances, if they are of benefit, are so because they liberate material in the soil which plants take up in growth, that had not previously been available. So you see that instead of adding any valuable plant food to tha soil, lime really makes it poorer in material for future growth. When you add to the soil barn-yard manure or commercial fertilisers, you arc supplying just that material with which land that is cropped needs replenishing. Secondly—Ground limestone can do nothing that cannot be accomplished by caustic lime. The only difference between the two is that the limestone contains carbonic acid which burned lime does not. The carbonic acid is not only of no use to plants when applied to the soil combined with lime, but rather the chances are greatly in favor of the lime doing more good without it. The decomposing effect of lime is principally what gives it value to the farmer, and if there is any difference in this respect, it certainly must be in favor of burned lime rather than the limestone. In our fertiliser experiments this year on the Central Experimental Farm, •we applied lime to one plot, and ground limestone to (another. The yield of oats per acre was exactly the same in the two cases, and but .little more than were no fertilizer was applied. No difference could be seen between the plots on which the two substances were applied ; SOOlbs of each were used on one-eighth of an acre. The experiment will be continued during a term of several years. If burned lime can be bought more cheaply than ground limestone, as I understand it can, I would prefer the burned lime by all means. And, let me add, that the only proper use of lime is on land to which considerable barn-yard manure or other fertilizer is applied. The use of lime without any true fertilizer has in numerous cases resulted in impoverished and broken down fields.