PROFITABLE FARMING. 21 



per acre every four or five years, but the cost of 

 these materials per ton should be less than 

 one-half that of ground lime. Of marl, from 

 2 to 5 tons per acre should be applied according 

 to the quantity of carbonate of lime which it 

 contains. 



In whatever form lime is used, it should be 

 applied in the autumn or early winter. As it 

 sinks in the soil it should never be ploughed in 

 on arable land ; it will travel downward quite 

 fast enough without the plough. It is always 

 preferable to plough the farm-yard manure into 

 the land first, then, after a few days, to spread 

 the lime on the surface and harrow it in. 



It has to be borne in mind that though lime 

 has the power of rendering available the dor- 

 mant plant food in the soil it is not in itself a 

 plant nutrient. Unless the supply of phosphate, 

 nitrogen and potash is provided by adequate 

 manuring, the ultimate effect of applications of 

 lime alone is to impoverish the land. 



In addition to the fertilisers already men- 

 tioned, containing only one element of plant 

 food, there are a few which combine two of them, 

 as, for example, Nitrogen with Phosphates and 

 Potash with Phosphates. 



Nitrogen and Phosphate 



In this class are to be found raw bones, 

 in the various well-known forms of bone meal, 

 steamed or boiled bone meal or flour, and dis- 

 solved bones, in which the bone has undergone 



