rains remove some or all
of the nitrate present in the soil. The clover remains thus afford a
more continuous source from which nitrates are produced, and greater
certainty for a good crop of wheat than when recourse is had to
nitrogenous top-dressings in the spring.

SUMMARY.

"The following are some of the chief points of interest which I have
endeavored fully to develope in the preceding pages:

"1. A good crop of clover removes from the soil more potash, phosphoric
acid, lime, and other mineral matters, which enter into the composition
of the ashes of our cultivated crops, than any other crop usually grown
in this country.

"2. There is fully three times as much nitrogen in a crop of clover as
in the average produce of the grain and straw of wheat per acre.

"3. Notwithstanding the large amount of nitrogenous matter and of
ash-constituents of plants, in the produce of an acre, clover is an
excellent preparatory crop for wheat.

"4. During the growth of clover, a large amount of nitrogenous matter
accumulates in the soil.

"5. This accumulation, which is greatest in the surface soil, is due to
decaying leaves dropped during the growth of clover, and to an abundance
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 yielding a better crop after
clover-seed than after hay.

"7. The development of roots being checked, when the produce, in a green
condition, is fed off by sheep, in all probability, leaves still less
nitrogenous matter in the soil than when clover is allowed to get riper
and is mown for hay; thus, no doubt, accounting for the observation made
by practical men, that, notwithstanding the return of the produce in the
sheep excrements, wheat is generally stronger, and yields better, after
clover mown for hay, than when the clover is fed off green by sheep.

"8. The nitrogenous matters in the clover remains, on their gradual
decay, are finally transformed into nitrates, thus affording a
continuous source of food on which cereal crops specially delight to
grow.

"9. There is strong presumptive evidence that the nitrogen which exists
in the air, in shape of ammonia and nitric acid, and descends, in these
combination