156 TALKS ON MANUUES. 



lliouirh not I'litinly, consist, is Iraiisfotinid into pasi'ous carbonic 

 acid, and wliat remains Itchind, hfcouus richer in nitroi^cn ami 

 mineral matters. A parallel case, showiiii; the dissipation of car- 

 bonaceous matter, and the increase in tiie percenta^a' of nitrogen 

 and mineral matter in what is left behind, is presented to us in 

 fresh and n»tten duuL'; in long or fresh dung, the j>ercenUige of 

 organic matter, consisting chietly of very imperfe-lly decom- 

 posed straw, being lirger, and that of nitrogen and mineral 

 matter smaller, than in well-rotted dung. 



"The roots froni the field after clover-.seed, it will be borne in 

 mind, were ilug uj) in November, whilst those ol)tained from the 

 lan<l twice mown, wen- tlug up in September; the former, there- 

 fore, may be expected to be in a more advanced state of decay 

 than the latter, and richer in nilroiren. 



" In an acre of soil, after clover seed, we have: 



IM. 



Nilrogtn in first six ii.chcs of soil 4,7"i5 



Nitroi^iii ill nnfts •'Jli 



Nitmiicn in seennti six inclioH of soil 'A,WM 



Tutal umouut of nitrogen, per aere, in twelve Inches of boU.... 8,l;afl 



"E(|ual to ammonia, 9,K(57 lbs. : or, in round numbers, 3 Urns 

 and 12i cwts. of nitrogen jier acre; eciual to 4 tons 8 cwt.s. of 

 ammonia. 



" This is a very much larger amount of nitrogen than occurred in 

 the other soil, and shows jtlainly that tiie total amount of nitrogen 

 accumulates especially in the surface-soil, when clover is grown 

 for seed ; thus explaining intelligibly, as it appears to me, why 

 wheat, as stated by many practical men, succeeds better on land 

 where clover is grown for seed, tlnm where it is mown f(jr hay. 



" All the three layers of the soil, after clover-seed, are richer in 

 nitroi,'en than the .same sections of the soil where the clover wjis 

 twice mown, as will be seen by the following comparative state- 

 ment of results: 



I. I n. 



MOWS. ANDTHBN LEPT PORBKKD. 



Upper I Seomd \ Third Vppfr \ Xtxl \ Lorrtft 

 %iiie/iei>. 6inrAfj>. Ciinche/t. (W/wAm. Sinchss. dinehe*. 



Perceiitasre of nitrogen in ; i I 1 



dried'soil .HW .092 I .OM | .189 | .\Z\ \ .089 



Equal to ammonia .198 | .119 ! .078 .229 | .169 i ,108 



"This difference in the amount of accumulated nitrogen in 

 clover-land, appears still more strikingly on comparing the tola! 



