This section is from the book "The Balance Of Nature And Modern Conditions Of Cultivation", by George Abbey. Also available from Amazon: The Balance Of Nature And Modern Conditions Of Cultivation.
Mr. James Howard, of Clapham Park, Bedford, having improved the recipe for an effective, but non-poisonous, dressing for seed corn which he made public two or three years ago, thus describes his present practice in the Tithes:"For 8 bushels of wheat, or 6 bushels of barley, take half a pint of gas tar, 2 lb. of blue vitriol, and 2 gallons of boiling water. The tar should be accurately measured (not guessed at), and should be of the consistency of treacle. After the tar is put into a pail, 1 gallon of water should be poured upon it, and well stirred; the black greasy scum which will rise to the surface should be skimmed off with a wisp of straw or piece of sacking, to which it will readily adhere. While this operation is going on another man should be mixing the [blue] vitriol with the other gallon of water. When ready both lots should be mixed together and poured over the heap of corn previously shot upon the barn floor; the heap should be well turned over two or three times quickly, so as to saturate the whole. If any tar or dregs remain at the bottom of the pail they should not be poured on the grain, or it will stick together in lumps, and be likely to clog the drill cups.
I have used this dressing for several years with complete success; not a single boy has been employed to mind the fields, nor has a gun been fired. The full plant, however, whether wheat or barley, has afforded evidence that no loss has accrued." (The Gardener's Chronicle, Vol. XII, new series, p. 658.)
The foregoing Dressing for Seed Corn answers for other kinds of seed against seed-eating birds generally as well as rooks, and also as a preventive of "smut" in cereals.