746 



As already stated, farmyard manure is used in some places in 

 large quantities, as much as 44 tons per acre being applied. The 

 potato is a plant that cannot easily assimilate its food from farmyard 

 manure as it is a surface feeder and should be liberally supplied 

 with readily available nourishment. A great deal of the apparent 

 benefit potatoes derive from farmyard manure is owing to its 

 mechanical action on the soil. 



Xitrate of potash has no better effect on the crop than nitrate 

 of soda, and the former is much dearer than the latter. Xitrate of 

 soda naturally gives better results than sulphate of ammonia. 

 Potash is best used in the form of a sulphate. The chloride 

 of potash should never be used for growing potatoes, and 

 the same thing applies to tobacco. Jamieson has proved that it 

 acts as a poison on these crops, and this has been confirmed by Munro 

 and Wrightson. Potatoes grown with the chloride of potash are 

 generally waxy. Although this crop demands a large amount of 

 potash, of which the ash contains from 55 to 60 per cent., vet the 

 application of too much is liable to increase the potato disease. 

 Superphosphate is undoubtedly the best form in which to apply 

 phosphates to this crop. The following mixture should ensure a 

 maximum crop, everything else being favorable : Fifteen tons 

 farmyard manure, ^ cwts. of superphosphates, i cwt. nitrate of 

 soda, or 9 cwts. of Thomas's phosphate might replace the super- 

 phosphate, and 4 cwt. of kainit the sulphate of potash. If farmyard 

 manure is not used, then use 5 cwts. superphosphate, 3 cwts. 

 sulphate of potash, and 2 cwt. of nitrate of soda. 



LEGUMINOUS CROPS. 



Leguminous crops are benefited most by potash manures, for 

 which they have a special liking. Although they absorb a large 

 amount of nitrogen, more than even cereals, yet they derive no 

 benefit from the addition of nitrogenous manures, on the contrary, 

 such manures may prove hurtful to them. This is a fact that has 

 been known to farmers for a long time, but only lately has the 

 explanation been made known by the discoverv that leguminous 

 plants have the power (which is not possessed by any other class 

 of plants, at least tb any great extent) <f absorbing nitrogen from 

 the air. ThK as already explained, takes place through the agency 

 of micro-organisms in the soil. Leguminous plants not only absorb 

 large quantities ol nitrogen from the air; but they al>o greatly enrich 

 the soil with nitrogen. Thus we see how land that has grown 

 leguminoiH crops for M>HU- time becomes so charged with nitro- 

 genous matter that it does not appeal" 1" grow any more ; Mich a^ a 

 field growing clover for some years when it gets clover-sick. It is 

 for this reason that cereals do best in a rotation after clover, the 

 large amount of nitrogen left in the soil by the previous crop being 

 available for the cereal crop. 



