302 MAXUEES AND THEIR APPLICATION. 



direction, and all improvements that have taken place in the 

 implements of cultivation from Small's swing plough to the 

 Darby digger are important as they enable the farmer to render 

 his soil more suitable for the nourishment of crops by hastening 

 the processes of weathering, which makes the riches therein 

 available for rapid assimilation by the plant, or in other words, 

 as they enable the farmer the more rapidly to exhaust the riches 

 of the soil. 



JSTone of the improved methods referred to did anything 

 towards increasing the total amount of plant-food contained in 

 the soil ; on the contrary, they all went indirectly towards 

 decreasing it. There was, however, one substance which was 

 imported upon the farm in considerable quantity, viz., lime. 

 Lime is a part of the food of plants, and essential to their 

 growth, and in so far as it was applied to soils deficient in that 

 constituent, liming was an important addition to the wealth of 

 the soil. But it was, and still is, customary to apply lime in 

 greater quantity that is necessary for plant-food, and to apply 

 it to soils which are in no way deficient in that material. The 

 application of lime was found, among other things, to cause an 

 increase of the crops, but this increase was not directly due to 

 the lime itself, but to its very complex action in the soil, whereby 

 it assisted weathering, and rendered the plant-food in the soil 

 more readily available. 



The old system of farming then meant exhaustion of the land, 

 and though by the introduction of one improvement after 

 another the exhaustion was less apparent, and the farming of 

 Scotland attained to a very high standard of excellence, yet we 

 see that it contained within it the elements of its decay. The 

 time must come, however it might be temporarily retarded by a 

 few great radical improvements, wdien the land would be no 

 longer able to be cultivated to the same extent, and be capable 

 of raising the same amount of food for the people. 



It was therefore a great new era for agriculture wdien it was 

 found to be practicable to augment the riches of the soil by the 

 application of imported and artificial manures. Shortly before 

 the time of thorough draining, bones began to be experimented 

 with in small quantities, and the results were so beneficial, that 

 their use increased from year to year, so that about 1840 some- 

 what over 1000 tons were in use. The annual consumption is 

 now over 40,000 tons, giving an av^erage increase of 1000 tons 

 annually. About the same time Peruvian guano began to be 

 imported, and in twenty years the annual consumption rose to 

 50,000 tons, and though a considerable falling off occurred there- 

 after, it is once more rapidly rising into favour. 



Chemical analysis showed that the powerful fertilising effect 

 of these manures was due to their containing chiefly two sub- 



