CH. iv] Losses of Nitrate 61 



During the wet winter of 1911-12 the following losses 

 took place from some micropped soils at Rothamsted 

 and Ridgmont: 



Loam in Poor 



good heart loam Clay Sand 



Rothamsted Rothamsted Ridgmont Milbrook 



Present in Sept. 1911 690 306 234 102 



Remaining in Feb. 1912 186 168 180 54 



Lost during winter 504 138 54 48 



Reckoned as lbs. of nitrate of soda in top 18 ins. per acre. 



The loss from sand is small because the stock happens 

 to be low, and from clay it is also small because percola- 

 tion of water does not readily take place. The most 

 serious losses are from good loams. In dry winters the 

 loss is less, but on an average the loam at Rothamsted 

 loses during winter months as much nitrate as would be 

 required by a 4 quarter wheat crop. 



If the student has access to drainage -water from 

 a field he should make the following experiments 

 periodically : 



( 1 ) Test for nitrate and compare with a standard solu- 

 tion to ascertain approximately the concentration (p . 2 2 8 ) . 



(2) Test for calcium. In many cases so much calcium 

 bicarbonate is present that a precipitate is thrown down 

 on warming the solution. 



The following experiment shows how a crop affects 

 the drainage. 



Take two glazed tubulated pots (Doulton's "mixing 

 jars" shown in Fig. 1), fill with soil, keep one pot fallow, 

 sow grass-seed in the other. Fit the tubulure with a 

 tight cork through which passes a glass tube bent so as 

 to deliver the drainage-water into a bottle. Measure the 

 amount of drainage after rain and estimate the nitrate 

 present. The experiment must run over the whole 



