778 EOTHAMSTED EXPERIMENTAL STATION. [DEC. , 



themselves, which still further extend the possibilities. 

 Broadly speaking, the effect of the tractor has been to speed 

 up all operations so much that work can now be done as a 

 genera] rule that formerly could only rarely be attempted. 

 Certain processes carried out* at Eothamsted are described below. 



Autumn Cleaning oi Stubbles. --Very marked benefit has 

 resulted from the cleaning of the stubbles which was carried 

 out at Eothamsted m the autumn of 1919, 1920, and during' 

 the present year. Corn crops, as every farmer knows, are 

 liable to infestation by weeds, and the stubble is apt to con- 

 tain quantities of weed seed. At the same time there is often 

 sufficient moisture in the soil at harvest time to allow the 

 germination of weed seeds if the surface is broken up directly the 

 crof is cut, but the moisture is rapidly lost if the land is left 

 bare and im worked for a short time. So long as horses only 

 were available it was impossible to carry out the necessary 

 cultivation quickly enough, but with the tractor the requisite 

 speed is obtainable and the land can be broken up. As an 

 example, Harpenden Field of 30 acres, on the Eothamsted 

 farm, had carried several corn crops during the War and was 

 very weedy in 1918; the weeds, however, were much reduced 

 by the stubble cleaning carried out with the tractor during 

 and just after the harvest of 1919. Wheat was sown in October 

 of that year and its stubble was cleaned in 1920; wheat again 

 was sown in 1920 and remained to the end fairly free from 

 weeds. The bare fallow or root crop that would have been 

 necessary in the old days was dispensed with, and sufficient 

 cleaning was effected in the autumn to bring the land back 

 to a satisfactory condition. It is now hoped to be able to deal 

 with the most serious of all the farm difficulties at Eothamsted 

 — the Broadbalk wheat field — winch has carried wheat con- 

 tinuously since 1843 and is distinctly foul. Messrs. Eansomes, 

 Sims and Jeffries have lent a broadshare that can be worked 

 by the tractor, and it is hoped that this will cope with the 

 serious weeds on this field: it certainly made good work in 

 breaking up the surface soil and cutting off the existing weeds. 



The second great advantage of the tractor is that it allows 

 of subsoiling. Experiments during the past four years have 

 shown that subsoiling increases the crop of potatoes by about 

 10 cwt. per acre, and also benefits the following wheat crop. 

 Experiments made elsewhere show much greater gains from 

 subsoiling wherever a plough sole has been allowed to form — 

 a common occurrence on the heavy lands of Essex. 



