A Statistical examination of the yield of mangolds from Barnfield at Rothamsted. (With Six Text-figures.)

Abstract

1. Series of yields (root weight) of twenty-five plots of Barnfield mangold field are analysed into components representing (a) deterioration, (b) slow changes other than steady deterioration, (c) annual fluctuations. The two first of these components are exhibited graphically from 1876 to 1930.2. Yields are well maintained on the dunged strip, except for the last few years. This falling off does not appear in the other strips, and may be due to a falling off in the quality of the farmyard manure in the last five years.3. On the strip receiving farmyard manure and on that receiving superphosphate the plots receiving nitrate of soda yielded more highly than any others; on the strips receiving complete minerals, and on that receiving superphosphate and potash, the two plots receiving rape cake in one case, and sulphate of ammonia and rape cake in the other, gave higher yields than nitrate of soda; on the strip receiving no minerals the result is intermediate, there being little to choose between these three plots. On all strips sulphate of ammonia is the least satisfactory of the four nitrogenous dressings tested.