Note 26 — CHAP. V. Of Tillage.

Roots cannot have any Nourishment from Cavities of the Earth that are too large to press against them, except what Water, when ’tis in great Quantity, brings to them, which is imbibed by the gentle Pressure of the Water; but when the Water is gone, those large Cavities being empty, the Pressure ceases; and this is the Reason, that when Land has few other but such large Cavities, the Plants in it always suffer more by dry Weather, than in Land which by Dung or Tillage has more minute and fewer large Cavities.

There may be some Moisture on the Superficies of large Cavities; but without Pressure the fibrous Roots cannot reach it; and very little or no Pressure can be made to one Part of the Root’s Superficies, unless the Whole that is included be pressed.

If it be objected that a Charlock-Plant, when pulled up, and thrown upon the Ground, will grow thereon; this proves nothing against the Necessity of Pressure, &c. for the Weight of that Plant presses some of its Roots so closely against the Ground, that they send out (unless the Weather be very dry) new Fibres into the Earth; and there they are pressed in all their Superficies; without which Fibres the Plant doth not grow.