420 



Effect of Chalk on Heavy Land. 



[Aug.', 



old four-course rotation the gain would have been obvious, but 

 now that the rotation is widened to one of six courses or more, 

 it is less evident. 



The ploughman always declares, however, that he can tell 

 by the ease of working where the chalk is applied, and during 

 the past six years attempts have been made to devise some means 

 of measuring the benefit obtained. So long, however, as we 

 were working with horse implements no success resulted. 

 Eecently a tractor has been substituted for horses in the main 

 work of cultivation, and among its advantages is the fact that 

 its work can be exactly measured and recorded. These measure- 

 ments are of great economic importance because the farmer pays 

 direct for every additional pound on the drawbar pull. The 

 Bothamsted Experimental Station is endeavouring to secure its 

 own dynamometer, but so far no satisfactory implement is on the 

 market. For the present purpose, however, we were fortunate* 

 in interesting the Hyatt Roller Bearing Co., and in borrowing 

 from them, not only their high class dynamometer, but also the 

 services of their Engineer, Mr. J. L. Bent, who took the 

 measurements and calculated the results. 



The particular field on which the measurements were made is 

 Pastures Field (also called Sawpit Field), which had been 

 ploughed in October, 1920, immediately after the oat crop was 

 removed. It was cross-ploughed in March last to a depth of 

 7 in., using an Austin tractor, and for part of the work a Ran- 

 some three-furrow plough, for the remainder a Cockshutt three- 

 furrow plough. The measurements recorded in Table II were 

 taken during this cross -ploughing. 



The figures show that chalking not only increases the speed of 

 ploughing but considerably reduces the drawbar pull, so that the 

 cultivation is effected by the expenditure of less work and there- 

 fore of less petrol and less wear and tear on the tractor and 

 implements. The increase in speed in the case of the Cockshutt 

 plough is from an average of 2.18 to one of 2.23 miles per hour : 

 in the case of the Ransome plough from 1.98 to 2.21 miles. 

 The drawbar pull fell from 1,538 lb. to 1,358 lb. for three 

 furrows with the Cockshutt. and from 1,610 to 1,425 lb. for 

 three furrows with the Ransome plough. 



The average of all results is a saving of 180 Ih. dratchar pull and 

 an additional mile of ploughing in every 9 hours 'work as a con- 

 sequence of chalking. The practical importance of this result 

 needs no emphasis. There can he little doubt that all other 

 cultivations are facilitated by chalking. Seeing that the chalk 



