artificial manure producing them. To obtain an exact knowledge of the 

 return yielded by the artificial manures when employed with farmyard 

 manure we must, however, go a step further, and ascertain what propor- 

 tion of the nitrogen of the artificial manure has been recovered in the 

 crop. It is the more necessary to do this, as a heavily manured root 

 crop is harvested in different seasons in very different stages of maturity, 

 and an immature crop, which an unfavourable season has prevented from 

 forming a large weight of root, may yet contain in ruot and leaf 

 almost as great a quantity of nitrogen, and furnish consequent- 

 ly almost as large a return for the nitrogen applied, as that which would 

 have been realised in a season of greater production of roots. The less 

 mature root is in fact more nitrogenous than the perfect root rich in sugar 

 and the green leaf far more nitrogenous than the root which it is its 

 function to produce. 



Determinations of nitrogen were made at Rothamsted in the roots 

 of all the plots of mangel-wurzel receiving farmyard manure during the 

 five years 1878-82. The amount of nitrogen in the leaf when the roots 

 were taken up was not determined, but ihz weight of the leaves, and the 

 amount of dry matter which they contained, were recorded. Determina- 

 tions of nitrogen were, however, made during these years in the leaves of 

 a series of other plots in the field receiving the same cross dressings. 

 By assuming that the dry matter of the leaves from the farmyard man 

 Tire plots contained the same percentage of nitrogen as was found during 

 the same years in the leaves of plots receiving the same cross-dressing 

 we may arrive very nearly at the total nitrogen contents of the farmyard 

 manure crops. In a later year, we shall presently mention, the amount 

 of nitrogen in both roots and leaves of all the mangel plots receiving the 

 farmyard manure was actually determined. 



Sir J. B. Lawes and Sir J. H. Gilbert have most kindly placed at 

 my disposal the results of the calculation we have just described. In the 

 the table on p. 32 will be found the average results of the farmyard 

 manure plots during six years, 1878-83. In calculating the nitrogen 

 contained in the roots of .1883 the average percentages of nitrogen in the 

 roots during the proceeding five years have been employed. 



Before considering the results it will be well to mention in what 

 manner the manures were applied during the years in question. At 

 Rothamsted the mangels are grown u on the ridge.' 1 During the years 

 in question the whole of the manures, save the dung, were sown broadcast, 

 and harrowed in before the application of the farmyard manure ; the only 

 exception being that the superphosphate was occasionally sown after- 

 wards by drill on the top of the ridge. The cross-dressings having 

 been thus applied, furrows were opened, and the farmyard manure was 

 placed in the furrow; the land was then bouted, the furrow being con- 

 verted into a ridge, along the top of which the seed was dibbled. 



The application of the nitrate of sodium at such an early date, and 

 before the farmyard manure, is clearly not what would now be recom- 

 mended in the light of recent knowledge, and we shall see presently that 

 this mode of proceeding has in later years been altered; but even with 

 this disadvantage the returns yielded by nitrate of sodium and ammonium 

 salts applied with farmyard manure are seen to be remarkably good. 



