NITROGEN EEMOVED BY A CROP. 125 



Oats, to ...... . 25 pounds. 



Barley, to . ' 22 " 



Wheat, to 22 '' 



These figures explain quite satisfactorily why some crops, 

 which contain, comparatively speaking, but small quantities 

 of nitrogen, quite frequently exhaust the soil far more in that 

 article of plant-food than others which contain a much larger 

 quantity of it. 



We know from exact comparative analytical tests, that an 

 entire average crop of wheat, rye, barley, oats, flax and 

 buckwheat contains but from thirty-eight to forty-five pounds 

 of nitrogen per acre, whilst hops, meadow-grasses, Indian 

 corn, rape, and potatoes, contain from fifty to seventy-five 

 pounds ; and, finally, tobacco, pease, lupine, lucern, and 

 beets, etc., contain not less than from seventy-five to ninety 

 pounds. Yet practical experience counts, when classifying 

 these crops with reference to their actual eflTect on the nitro- 

 gen plant-food of soils, grain-crops, rape, tobacco, potatoes, 

 and other hoed crops, jimong the very exhausting crops ; 

 pease, vetch and buckwheat among the most saving ones ; 

 and clover, lucern, esparcet, lupine, etc., among those which 

 enrich, in a decided degree, the soil with nitrogen plant-food. 

 To introduce the last-named class of crops, whenever practi- 

 cable, into a system of rotation will always operate in the in- 

 terest of an economical use of nitrogenous fertilizers. 



The second step towards an accumulation of ready nitrogen 

 plant-food consists in the saving of all vegetable and animal 

 refuse material, incidental to the industry pursued ; for all 

 contain more or less nitrogen compounds, and difier in fact 

 more in regard to the quantity than the quality which they 

 contain. 



The most prominent substances, which deserve in this con- 

 nection our attention, are the animal secretions. 



The quality of these refuse matters depends, first, on the 

 kind, the age, and the employment of the animal from which 

 they are obtained ; and secondly, on the kind and the amount 

 of food consumed. 



Every class of our domesticated animals requires' for its 

 daily support a certain varying amount of nitrogenous com- 



