CHAPTER IX. 

 LIME AND LIMING LAND. 



The substances of which we have been treating in the past three chapters, 

 nitrogen, phosphoric acid and potash, are direct fertilizers, or plant foods. 

 We come now to the consideration of the forms which are most useful as re- 

 agents, or, as we may say, stimulants to the productive capacity of the soil. 

 While it is true that calcium of which lime is the oxide when freshly made, 

 is one of the elements essential to plant growth, it is usually found in all 

 cultivated soils in almost inexhaustible quantities for all the purposes of 

 direct plant feeding. Yet an application of freshly slaked quick lime (or 

 hydrate of calcium), will often have a marked effect on the productiveness 

 of the soil, through its action in releasing other forms of plant food, particu- 

 larly potash, from the insoluble silicates in which it occurs in the soil. 



Lime is also important in a soil abounding in organic matter, as it cor- 

 rects the acidity of such soils, and enables the nitrifying microbes to thrive 

 and do their work in bringing the nitrogen of the organic matter into the 

 available form of a nitrate. Hence the old proverb that "Lime enriches the 

 father and impoverishes the son," for it enables us to get at the plant food in 

 the soil, and if used with the notion that it is simply a manure we may soon 

 find that its use has tended to exhaustion. Judiciously used, however, there 

 is nothing that is a greater aid in the development of the farm. Lime also 

 has an important mechanical effect on soils. It renders a heavy clay soil 

 more friable by gathering it into small lumps, or flocculating it, as it is 

 called. On a sandy soil it sinks and forms a compact layer below the plow, 

 and thus renders the soil less leachy. But in many sections where there is a 

 fertile soil well supplied with humus, the application of lime has at first pro- 

 duced such marked results that the farmers have jumped to the conclusion 

 that lime is all they need to keep up the productiveness of their lands. After 

 a while they find that the lime has less and less effect, and they are compelled 

 to resort to commercial fertilizers for the production of crops. We recently 



(77) 



