Applying Agricultural Lime

King Country Chronicle, Volume VIII, Issue 694, 15 August 1914, Page 7

Applying Agricultural Lime

CRUSHED OR SLAKED. Crushed lime consists of quick lime, burnt lime, or lime shells, crushed 'into a fine powder after it has been burned in a lime kiln, and the advantages' claimed for it, as compared with the 8 same lime slaked in the field by water* or by atmospheric moisture are that it can- be much better distributed in the form of a fine powder, that it can thus be applied in much smaller .quantity, that it is much more convenient to handle, a nd that it is, applied in 'lts most effective caustic form. Some of these advantages are undeniable. Lime slaked in small heaps is not found to be in a very fine state of division, but consists in great part of sticky masses and- lumps, which do not admit of being very uniformly spread' over the soil. and which cannot be so intimately 'intermingled with its particles as is the powder of crushed lime. Neither ?«.i it found in practice thati slaked lime can be distributed, even imperfectly, with any approach to completeness or uniformity unless it be applied in quantities of not less than about two tons per acre. In consequence of its moist and adhesive character it cannot be sown by any sowing machine, and spreading the heaps with shovels both necessitates the larger application and renders it at the same time less regular and equal. On the other hand' crushed lime • is sent out as a dry powder, which can be distributed very vniformly and easily over the soil in quantities of only a few cwts. per acre. The application of lime in the crushed form would therefore appear to be distinctly the preferable method, and so it would be were it not for the question of cost. Unfortunately the process of crushing the burnt lime is somewhat; expensive, and crushed - lime is commonly sold at prices ■ nearly 50 per cent, higher than the uncrushed lime shells. A consideration of this, objection to the use of .crushed lime led to the institution of experiments by the ?7est of Scotland Agricultural College. . The object of this experiment was to determine whether burnt lime could not be slaked in such a manner as to produce a dry and 'ine powder capable of being sown in small quantities by a manure sowing machine, and at less cost than that of the crushed dime. For this purpose a) ton of Itime shells was purchased and set in a heap in a corner of the experiment field* with convenient aecess to water. Water was at, onee brought to the heap and poured on it. The. quantity 0 f water required for the slaking was 20 gallons per ton •of crushed lime. The heap was.immediately covered with a few inches of earth. About twelve hours later it was turned over. w a tej? was applied to all lumps that remained unslaked, the lime was then passed through a half-inch riddle to take out stones and unslackable lumps, and the slaked lime thus riddled was "found to remain in the form of a very fine dry powder, whicv. was sown without difficulty by a m a nure : sowing machine. In order to catch lime in the proper condition for sowing, the stones have to be .separated by riddling not less than twelve nor more than 24 hours after' the first watering ; and after the stones have been separated by riddling, the; lime must be sown without delay,' or it will become sticky and incapable of beinp sown by. machine. But, taken at the right time, the limo is' found to be in the state of a very fine and dry powder, capable of the most uniform distribution in very small quautity. The costs of the various operations which were carefully calculated, were as follows : Cost of lime shells at kiln per ton 12/-!; cost of slaking and covering with earth, 5d.,; cost of turning heap and slaking' remaining lumps. sd. ; cost oi riddling, through A-in. riddle, lOd. ; total cost per ton, 13/8 : cost of crushed lime per ton at kiln, 18/-. Balance in favour of slacked lime per ton, 4/4. It Avill be seen, therefore, that it is jqu'it'e possible to', slake .lime in such a \ manner that it can be- sown in quantities as small as crushed lime, and in a form capable of an equally- uniform and' complete distribution. The advantage in both respects is reported as being with the slaked lime, as the burnt lime in the process or slaking breaks up into a much finer powder than that produced by crushing, and it alsc swells into a bulk so much greater that much smaller quantities can be sown ■ without difficulty by the machine. The only practical drawback is that the lime must be applied immediately after tho slaking has been completed, and that accordingly large quantities cannot be slaked at the sams time. This, however, can be regarded as a small difficulty as against the importan! fact that the slaked lime can be applied 'in the manner described at a cost per ton so much less than thai of the crushed material. The superiority of the method of applying lime in the slaked form is thorefon manifest.—"The Leader."