INSTITUTE AND COLLEGE, PUSA, FOR 1912-13. 19 



These quantities are naturally much greater than what 

 is lost from agricultural land. At Pusa the records show 

 that from fallow soil the annual loss is (approximately) 

 28", at Cawnpore 18". Where crops are growing the 

 quantities of water which are evaporated and transpired are 

 somewhat greater 1 though the difference is not large- 



The data regarding soil temperatures now extend over 

 two years and they will be written up with a view to publica- 

 tion. They have shown that at Pusa, with a maximum 

 hot weather temperature of, say, 110° F. (43° C.) the fol- 

 lowing maxima are realised in fallow soil : — 



1" from surface ..... 

 2" from surface 



3 ;/ from surface .... 



6 /; from surface .... 



The air temperature of many parts of India rises con- 

 siderably above that of Bihar. In the Punjab maximum 

 temperatures of 115° to 120° F. (46°— 49° C.) are regularly 

 registered for some weeks during the hot season and there 

 the upper soil will naturally attain a correspondingly 

 higher temperature than has been recorded at Pusa. 



It has recently been shown 2 by Russell and Hutchinson 

 that heating a soil to 122° F. (50° C.) occasions material 

 biological changes of a beneficial nature, and that if a soil 

 is heated for a sufficiently long time to 40° C. (104° F.) 

 similar changes may occur. 



Such soil temperature records therefore become of some 

 practical importance. At the same time it must not be for- 

 gotten that not only is this subject a new one and at present 

 very imperfectly understood, but also that in any case 

 it is only the topmost 3" — 4" which are liable to such 

 temperatures, whilst below this depth these biological 

 changes are presumably either modified or non-existent. 

 Also that the cultivating implements annually cause an 



1 Memoirs, Department of Agriculture in India, Chemical Series, 

 Volume II, No. 2, pages 12 — 14. 



2 Journal of Agricultural Science, V, pages 152 — 220. 



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