1905.] 



On the Retention of Bases by the Soil. 



7 



Table III.— Broadbalk Wheat Soils — collected at various dates. 



Calcium Carbonate per cent, in Fine Soil Dried at 100° C. 



Plot. 



Manures. 



Sept., 



Oct., 



Oct., 



Oct., 



Sept., 



1856. 



1865. 



1881. 



1893. 



1904. 



1st Depth (1 — 9 inches). 







p. c. 



p. c. 



p. c. 



p. c. 



p. c. 



25 





4-20 



3-79 



3 46 



3-28 



3 





5 -35 



4-54 



3-97 



3 -45 



3 29 



5 



Full minerals 



5-65 



4-96 



3-75 



3 -34 



2-94 



6 









3-41 



1 -98 



2-33 



7 



„ + 400 lbs. „ 





3-82 



3-19 



2-36 



2 -25 



8 



„ +600 lbs. „ 







2 -84 



1 -73 



1 -76 



9 



,, +275* lbs. nitrate soda 





4-24 



3-99 



3-72 



3-36 



10 



400 lbs. ammonium salts only 



5 -41 



4-10 



3 -31 



2 -76 



2-47 



11 



,, and superphosphate... 





4-36 



3-14 



2 -76 





2nd Depth (10—18 inches). 



25 







0-277 



0-310 



0-422 



0-237 



3 







0-222 



0-162 



0-099 



0-116 



5 







0-147 



0-128 



o-ioo 



0-110 



6 



,, +200 lbs. ammonium salts 







-no 



0-114 



0-132 



7 



„ +400 lbs. „ 





0-212 



-210 



0-096 



0-167 



8 



+ 600 lbs. „ 







106 



0-093 



0-117 



9 



,, + 275* lbs. nitrate soda 





0-309 



0-263 



0-482 



143 



10 



400 lbs. ammonium salts only 





-127 



0-137 



0-170 



o-m 



11 



„ „ and superphosphate... 





0-119 



0-179 



0-107 





3rd Depth (19—27 inches). 



25 



Farmyard manure (14 tons) 





0-181 







•121 







•130 







•095 



3 







0-179 







•090 







•084 







113 



5 



Full minerals 





0-056 







•079 







•050 







•100 



6 













•058 







•073 







112 



7 



„ +400 lbs. „ 





0-144 







■115 







•075 







•136 



8 



„ +600 lbs. „ 











•063 







•104 







•122 



9 



„ + 275* lbs. nitrate soda 





-144 







•102 







•130 







•116 



10 



400 lbs. ammonium salts only 





0-073 







•070 







•070 







•105 



11 



„ „ and superphosphate... 





0-090 







•089 







•085 







* Double this amount applied from 1855 to 1884 inclusive. 



with saline manures and the gradual loss of organic matter. On the contrary, 

 the soil of the plot receiving farmyard manure grows lighter through the great 

 accumulation of organic matter. These changes of weight would be of little 

 moment were the soil uniform, but as the calcium carbonate is almost wholly 

 present in the surface soil down to about six or seven inches, small variations 

 in the thickness of the slice taken by the tool cause a varying admixture of 

 the poorer subsoil, and so may induce considerable change in the estimated 



