52 



PLANT PRODUCTS 



fermentation, and to prevent loss by drainage. The loss by 

 drainage may be very pronounced, even under carefully 

 controlled conditions. In a series of experiments conducted 

 at Cockle Park I found the results which are condensed in 

 Table ii. The sampling of farmyard manure presents great 

 difficulties, hence the error of experiment is very large, but 

 in the last column of the table I have expressed the average, 

 with the probable error of the series. 



Table ii. — Storage of Farmyard Manure in Cement Pits, 

 Cockle Park. 



Losses and Gains during Six Months' Storage. 



It will be seen that when manure is kept in the circum- 

 stances stated, the organic matter and total nitrogen that 

 are lost amount to about 15 per cent., within a reasonable 

 margin of error, that the loss of potash is even greater, but 

 that the phosphoric acid gives no evidence of any loss. The 

 potash could, under those circumstances, only have been 

 lost by drainage ; the nitrogen might have been lost either 

 by drainage or as elementary nitrogen. About a half of 

 the nitrogen would have been insoluble in water, and of the 

 remaining half some at least would have been in the colloidal 

 form, difficult of diffusion. One would, therefore, expect 

 that if 23 per cent, of potash can pass away by drainage, 

 the nitrogen loss by drainage should be less than half that 

 figure. I/ittle error in these experiments would occur from 

 nitrogen fixation, since the dung was made by bullocks. 

 There may be, therefore, a slight loss of nitrogen into the 

 atmosphere, but it is very clear that the most pressing 

 reform is to prevent loss by drainage. In places where there 

 is a pit, to collect the drainage, the drainage is pumped up 



