"I meant such investigations as those at Rothamsted and also those
conducted at Pennsylvania State College. I have some of the exact
data here in my note book.

"In 1848, Sir John Lawes and Sir Henry Gilbert began at Rothamsted,
England, two four-year rotations. One was turnips, barley, fallow,
and wheat; and the other was turnips, barley, clover, and wheat.
Whenever the clover failed, which has been frequent, beans were
substituted, in order that a legume crop should be grown every
fourth year.

"The average of the last twenty years represents the average yields
about fifty years from the beginning of this rotation.

"In the legume system, as an average of the last twenty years, the
use of mineral plant food has increased the yield of turnips from
less than one-half ton to more than twelve tons; increased the yield
of barley from thirteen and seven-tenths bushels to twenty-two and
two-tenths bushels; increased the yield of clover (when grown) from
less than one-half ton to almost two tons; increased the yield of
beans (when grown) from sixteen bushels to twenty-eight and
three-tenths bushels; and increased the yield of wheat from
twenty-four and three-tenths bushels to thirty-eight and four-tenths
bushels per acre.

"In the legume system the minerals applied have more than doubled
the value of the crops produced, have paid their cost, and made a
net profit of one hundred and forty per cent. on the investment, in
direct comparison with the unfertilized land.