160 TALKS ON MANUP.KS. 



pliosphoric acid, lime, aud other mineral matters, which enter into 

 the composition of the asiies of our cultivated crops, than any other 

 crop usually grown in tliis country. 



"3. Tliere is fully tlireu times as much nitrogen in a crop of 

 clover us in the average produce of the grain and straw of wheat 

 per acre. 



"3. Notwithstanding the large amount of nitrogenous matter 

 and of a.sh-constituents of plants, in the produce of an acre, clover 

 is an excellent preparatory crop for wheat. 



" 4. During tiie growth of clover, a large amount of nitrogenous 

 matter accumulates in the soil. 



"5. This accumulation, whicn is greatest in the surface soil, is 

 due to dcc'ying leaves dropped during the growth of clover, and 

 to an ahundance of roots, containing, when dry, from one and 

 three-fourths to two per cent of nitrogen. 



" 6. The clover-roots are stronger and more numerous, and more 

 leaves fall on the ground when clover is grown for seed, than 

 when it is mown for hay ; in consequence, more nitrogen is left 

 after clover-seed, than after hay, which accounts for wheat yiehl- 

 ing a l)etter crop after clover-seed than after hay. 



" 7. The development of roots he\n[s checked, when the produce, 

 in a green condition, is fed olT by shtep, in all jirohaltility, leaves 

 still less nitrogenous matter in the soil than when clover is 

 allowed to get riper and is mown for hay ; thus, no doubt, account- 

 ing for the observation made by practical men, that, notwithstand- 

 ing the return of the produce in the sheep excrements, wheat is 

 generally stnngcr, and yi"lda better, after clover mown for hay, 

 than wlien the clover is fed off green by sheep. 



"8. Tlie nilrogMious matters in tlie clover remains, on their 

 gradual decay, are finally transformed into nitrates, thus affordinix 

 a continuous .source of food on which cereal crops speeially dcliglit 

 to grow. 



"9. There is strong presumptive evidence that the nitrogen 

 wliieh exists in the air, in shape of ammonia and nitric acid, and 

 descends, in these combinations, with the rain which falls on the 

 ground, satisfies, under ordinary circumstances, the requirements 

 of the clover-crop. This crop causes a large accumulation of 

 nitroi^enous matters, which are gradually changed in the soil into 

 nitrates. The atmosphere thus furnishes nitrogenous food to the 

 succeedin'r wheat indirectly, and, so to say, gratis. 



"10. Clover not only provides abundance of nitrogenous food, 

 hut delivers this food in a rea lily available form (as nitrates), more 

 gradually and continuously, and, consequently, with more cer- 



