37 



applied too late, a large proportion of leaf to root is found when the crop 

 is taken up, time not having being allowed for root formation. 



In the crops grown with farmyard manure in 1897 the nitrogen 

 has been determined both in root and leaf. For the crop grown in 1896 

 the nitrogen in the root is known, and the weight of the leaf ; the per- 

 centage of nitrogen in the leaf is assumed to be the same as in corres- 

 ponding experiments. The results of these two years have been kindly 

 supplied by Sir J. B. Lawes and Sir J. H. Gilbert ; they will be found 

 on p. 38. 



As soon as we deal with the results of individual seasons we en~ 

 counter the irregularities inseparable from field experiments. In the 

 results before us more than one of the applications of nitrogenous manure 

 has apparently yielded double the return of nitrogen in the crop in 1897 

 than it did in 1896 ; this is notably the case where rape-cuke has been 

 applied. The increased utilisation of the manures in 1897 is but little 

 shown by the weight of crop per acre ; the severe drought of July and 

 August arrested the development of the mangels, and when taken up in 

 November they contained an undue proportion of leaf, the materials accu- 

 mulated in which had not had sufficient time to bring about the elabora- 

 tion of sugar, and the construction of a larger root. 



Taking the mean of the figures at the bottom of the table, where 

 a correction is made for the effect of the leaves left on the land in th© 

 previous season, we have the following proportions of nitrogen recovered 

 in the increase of produce for 100 supplied in the undermentioned man- 

 ures, applied as cross-dressings on dunged land, with and without the 

 addition of basic slag and sulphate of potassium. 





Nitrate of 

 Sodium 

 861b. nitro- 

 gen. 



Ammon- 

 ium Salts 

 861b nitro- 

 gen. 



Rape -cake 

 961b nitro- 

 gen. 



Ammon- 

 ium Salts 

 and Rape- 

 cake 1841b 



Farmyard manure alone 



81-9 



597 



58-9 



39 3 



" with slag and 











potash 



95 9 



77-8 



587 



49-5 



Comparing these figures with those previously given, we especially 

 notice the increased return from the nitrate, due doubtless, to its applica- 

 tion later in the season. The farmer must not, however, apply the nitrate 

 too late, as happened in the present case, for nitrogenous leaves will be 

 no compensation to him for the lack of roots. The higher return given 

 by nitrate of sodium than by the other manures is doubtless in part due 

 to the soda supplied ; in the mangel-field, the plot receiving soda and 

 magnesia, in addition to potash and phosphates, is the one giving the 

 highest return, excepting the two plots manured with farmyard manure. 



It is now, 1 think, clear that under the conditions in which farm- 

 yard manure is employed in the mangel field at Hothainsted the 



