Agricultural Field Experiments

Abstract

MR. HOWARD'S letter in NATURE of Jan. 31 (p. 166) gives interesting confirmation of the reviewer's opinion in NATURE of Nov. 29, p. 843, that depth of sowing influences the yield of wheat, yet I venture to suggest that such an extreme case as he quotes scarcely bears upon the point at issue. When seeds do not germinate, it is equivalent to a light seeding rate, which, as I pointed out, makes wonderfully little effect on the yield. Whether such differences as one may expect to occur between the depths of coulters in the same drill make any appreciable effect on the yields of the different rows is still, I think, an open question, and I suggest that the differences which the reviewer has observed between the yields of his rows may have been due to their being unevenly spaced. The yield which is comparatively unaffected by seeding rate, is that per areal and not that per linear unit. The reviewer quotes “an apparently uniform field” at Aarslev as upsetting my view that for practical purposes randomness can be obtained from the half-drill strip “provided care is taken to drill across ploughman's ‘lands’”, if they exist; yet Dr. Sanders in his account of that experiment makes no mention of an “apparently uniform field” (Journal Agricultural Science, 20, p. 65), but writes, “This oscillation apparently arose as a legacy of the old practice of ploughing in high ridges”, and so on.