A quote that one has to be rich to engage in science?
I am not sure the quote actually exists. In Democracy in America, de Tocqueville posits a scenario where the absence of the wealthy would stifle science:


  It is possible to conceive a people not subdivided into any castes or scale of ranks, among whom the law, recognizing no privileges, should divide inherited property into equal shares, but which at the same time should be without knowledge and without freedom. Nor is this an empty hypothesis: a despot may find that it is his interest to render his subjects equal and to leave them ignorant, in order more easily to keep them slaves. Not only would a democratic people of this kind show neither aptitude nor taste for science, literature, or art, but it would probably never arrive at the possession of them. The law of descent would of itself provide for the destruction of large fortunes at each succeeding generation, and no new fortunes would be acquired. The poor man, without either knowledge or freedom, would not so much as conceive the idea of raising himself to wealth; and the rich man would allow himself to be degraded to poverty, without a notion of self-defense. Between these two members of the community complete and invincible equality would soon be established. No one would then have time or taste to devote himself to the pursuits or pleasures of the intellect, but all men would remain paralyzed in a state of common ignorance and equal servitude.


(Source: http://xroads.virginia.edu/~hyper/DETOC/ch1_09.htm)

However, he immediately goes on to dismiss this argument. There might be some more concrete examples regarding farms/farmers in the book, so you can try to take a look, but it does not seem too likely (or, as often happens, the popular magazine took the quote out of context).