J. H. Oilbert- 



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the ammonia <>i the air within the pon-s of the soil, and by the 



Let us now em, side,- what is the vie'ld of nitrogen by plants 

 of other natural families, and first of all l>y certain so-called 



beet of the order Chenopodiaceae. On this point we have the 

 experience of thirty-one years, excepting that during three of 



equalise the condition 1,1 th . before re- 



arranging the manuring, and during two other years the turnips 

 fa, led and there was no croD. 



It should be premised that when root-crops are grown with- 

 out manure of any kind, there is after a feu rears scarcely any 

 produce at all ; and hence the results recorded in the table are 

 those obtained by the use of mineral manures, hut without any 

 supply of nitrogen. It is seen that .hiring the first eight years 

 of turnips, there was an an ratr* ield of 42 lbs. of niiWen ,, P r 

 acre, per annum. During the next three years harlev vie!, led 

 24-3 lbs. annually. During the next fifteen years, thirteen v, ith 

 Swedir-h turnips.' and two 'without an v crop, there was a yield 

 of 18-5 lbs. per acre annually. Durir.sr the last live vears .near- 

 beet yielded 131 lbs. per acre, per annum Lastlv, over the 

 whole' thirty-one years, during which there were three crops of 

 barley, two vears without any crop,, twenty-one years of turnips, 

 and five of sugar-beet, the average annual yield was 26'8 lbs. 



Here, then, we have a reduction to less than one-third during 

 the later compared with the earlier years, and to a lower point 

 than even with either wheat or harlev: thou-rL, during the 

 whole period, the annual yield is higher man with either of the 



- - 



cropa" < . la vers of the soil of 



v» e s lie's of nitrogen, more completely than per- 

 haps any other crop. It may further be adde 1 that the surface 



... ■ . - ■..■■■ ■ - v; 



have fair grounds for concluding, therefore, that il in the eases 

 of the wheat and the barley the nitrogen yielded beyond That 

 retained by thesoil from the direct measurable aqueous deposits, 



