Science and Crop Production¹

Abstract

THE beginning of much of our scientific work on crop production goes back to the year 1843, when Lawes and Gilbert set out to discover why farmyard manure is such an excellent fertiliser. Two opposing explanations were offered by the chemists of the day; the older view, coming down from the eighteenth century, was that the fertilising value lay in the organic matter; the newer view put forward by Liebig in 1840 was that it lay in the ash constituents the potash, phosphates, etc.—left after the manure is burnt. Lawes and Gilbert considered that it lay in the ash constituents plus the nitrogen of the organic matter, and they devised a critical field experiment to decide the matter. They divided a field of wheat into plots of equal size, of which one received farmyard manure at the rate of 14 tons per acre, another received the ashes of exactly the same dressing of farmyard manure, a third received the mineral matter of the ashes plus some of the combined nitrogen that had been dissipated on burning, and a fourth lay unmanured. The results were very striking:—