20 



Mr. A. D. Hall and Dr. N. H. J. Miller. [Mar. 30, 



contains 132 parts of lime per million, the plot receiving the same minerals 

 and sodium nitrate gives a drainage water containing 126 parts of lime per 

 million. Thus where the nitrate is used there is both a lower concentration 

 of lime in the drainage water and a smaller total percolation, because of the 

 much greater crop, and consequently increased transpiration on this plot. 



The sodium nitrate then either saves the calcium carbonate of the soil from 

 its normal loss or has some power to bring about the re-formation of calcium 

 carbonate. With this fact must be correlated the non-disappearance from 

 the other plots of the calcium carbonate required to form calcium nitrate with 

 the nitrified ammonia base. 



Considering lastly the plots receiving farmyard manure, the Broadbalk 

 Field shows a much lower rate of loss on the plot manured every year in 

 this way than on the unmanured plot, 590 lbs. against 800 lbs. per acre per 

 annum. The corresponding plots in the Hoos Field hardly confirm this 

 view, since both the plot receiving farmyard manure and that receiving rape 

 cake, the only other organic manure employed, appear to be losing calcium 

 carbonate at much the same rate as all the other plots. However, as the 

 Hoos Field results rest upon determinations made at two dates only instead 

 of four as in the case of Broadbalk, it is much more probable that the result 

 yielded by the latter is trustworthy. The subsoil of the plots receiving farm- 

 yard manure also show amounts of calcium carbonate above the normal — - 28, 

 0-31, 0-42, and 0'24 in Broadbalk, and 0-28 and 015 in Hoos Field. The 

 drain beneath the farmyard manure plot on the Broadbalk Field runs but 

 rarely, because the humus derived from the long-continued organic manuring 

 of this plot is capable of temporarily absorbing any ordinary rainfall and then 

 passing it gradually down to the subsoil without causing the drain to run. 

 But the few analyses that have been made of the water draining from this 

 plot indicate a lower concentration in calcium compounds than would be 

 expected from the large amount of carbon dioxide produced by the decay of 

 recent organic matter, and also from the considerable annual addition of 

 calcium compounds in the manure itself. The composition of farmyard 

 manure is very variable, but the mean of a number of analyses gives - 6 per 

 cent, of CaO, or an annual application of 190 lbs. per acre, of which the 

 greater part is in combination with organic acids. There is, therefore, an 

 addition of calcium compounds in the manure more than equivalent to their 

 greater concentration in the drainage water, and the net result is a gain of 

 calcium carbonate to the soil as shown by the diminished rate of loss on this 

 as compared with the unmanured plot. 



W e thus obtain three lines of evidence that there is some agency saving or 

 re-creating the calcium carbonate of the soil : (1) the loss of calcium carbonate 



