674 Summary of Agricultural Experiments, [nov., 



thre,e different situations at Rothamsted, one dish in each pair at about 

 two inches above the ground, and the other at about four feet. Dishes 

 were thus exposed for two years, and the contents were analysed and 

 changed monthly. The highest average amount of ammonia collected 

 in a year represented 1*533 lb. P er acre °* nitrogen. This was in the 

 lower dish over arable land. The amount is, however, partly due to 

 evolution of ammonia from the soil after the application of ammoniacai 

 manures. Leaving out of account, however, the period in which the 

 influence of these manures is noticeable, absorption was greater 

 for the higher dishes than the lower, and greater over arable land than 

 over grass, except where chimneys near the grass land contaminated 

 the air. The dishes were covered with fine gauze in order to exclude 

 insects and as much dust as possible, and to this precaution the authors 

 attribute the much smaller amount of nitrogen absorbed than in similar 

 experiments abroad. The smaller absorption by the acid close to the 

 soil is attributed to the less frequent renewal of the air around the 

 dishes than at a greater height, but it might be taken to be due to 

 reduction in the ammonia in the air close to the soil owing to absorp- 

 tion by the soil. On the other hand, any absorption by the soil would 

 have been expected to be greater over arable land than over grass, 

 and the larger amount of nitrogen collected by the acid over arable 

 land would not accord with this view. Until it has been determined 

 whether there is any difference in the ammonia content of the air at 

 the two heights dealt with here it is impossible to come to any definite 

 conclusion as to whether the soil is absorbing or giving off ammonia. 

 It can be concluded with some confidence, however, that if the soil 

 normally absorbs ammonia the total amount of absorption is very 

 small. Even assuming that the soil is as effective an absorbing agent 

 as the sulphuric acid used in the experiments the maximum absorption 

 per annum amounts to less than a pound per acre, a quantity that 

 would be negligible in any estimates of the gains and losses of nitrogen 

 on a given piece of land under any method of treatment. 



Calcium Cyanamide and Nitrate of Lime (James Hendrick, Jour. Soc. 

 of Chem. Industry, No. 9, Vol. 30, May i$th, 191 1). — This paper con- 

 tains a short account of the experiments with nitrogenous manures 

 which were noticed in this Journal for May, 1910, p. 134, and gives 

 the results of additional trials carried out in 1909. Nitrate of lime 

 has generally given better results than other nitrogenous manures. 

 Many of the soils in the north-east of Scotland are very deficient in 

 lime, and the superiority of this manure in the district is attributed 

 to the lime contained in it. 



Green Manuring (Rept. on the Wohurn Field Expts., Jour. Roy. 

 Agric. Soc, Vol. 71, 1910). — Tares, rape, and mustard were grown in 



1909 and ploughed in, and the effect of mineral manures was compared 

 with that of lime in the case of each green crop. The crop grown in 



19 10 was wheat, the average yields from the two tares plots being 

 147 bush, per acre, from the two rape plots 2i'6 bush, per acre, 

 and from the two mustard plots 22*3 bush, per acre. Lime 

 proved superior to mineral manures with each green crop, a result 

 possibly due to the depletion of the soil in lime. The results show that 

 on a soil such as that of Woburn mustard is a better crop for ploughing- 



