May, 1921. 



SCIENTIFIC AGRICULTURE 



205 



did in theory. We have no time for that sort of 

 thing and don't care. Listen! If it takes 1.000 

 pounds to pull a two-furrow gang plow cutting 28 

 inches and plowing 8 inches deep in summerfallow, 

 and only 600 pounds to pull 6 sections of drag harrows 

 covering a strip of ground 24 feet wide, does it sound 

 reasonable to you as a practical man to make a 

 four-horse team do the work in each case? The 

 plowing is a G^horse job and the harrowing a 4-horse 

 job. Now it Is some trouble to switch your whipple- 

 trees and harness around, but it may pay you to do 

 so occasionally. Give your teams a fair average day's 

 work and not an overload one day and an underload 

 the next. Of coui-se t;ie harrowing offers poorer foot- 

 ing. Let us now discuss some of the factors influ- 

 encing the draft, of plows. 



(a) Shape of the moldboard. 



(b) Condition of the plow. 



(c) Sharpness of shares. 



(d) Scouring qualities of plow and soil. 



(e) Various adjustments. 



(f) Colters and their effect on draft. 



(g) Size of furrow, 

 (■h) Line of draft. 



The stubble moldboard having a sharp- quick turn- 

 pulverizes the .Sdil to a greater extent than the breaker 

 bottom. It does more work and tlierefore takes more 



jn^ 



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power. The steeper the moldboard. the more power 

 will it require. 



Condition of the Plow. 



A plow frame with loose bolts and worn wheel 

 boxings cannot be expected to do good work. Your 

 wife does not let her sewing machine get all loo.sened 

 up. She oils it and takes care of it; that is why it 

 lasts a life time. Manufactur-ei's are endeavouring to 

 eliminate this trouble by specifying spring washers on 

 every bolt and in maJiy cases hot rivetted frames are 

 replacing those held together by common bolt;■^ and 

 nuts, which will work loose. 



Sharpness of Shares. 



The power absorbed in severing the furrow slice 

 demands that shares be not only sharp but properly 

 sharpened. Sanborn reports a difference of only 6.7 

 per cent in favor of an old point res;iarpeued over 



a dull point in the same plow, but an advantage of 

 36 per cent in favor of a new point over the old point 

 resharpened. At all events farmers should not waste 

 time on dull shares. Great care should be taken when 

 sharpening shares to return them with the same "set". 

 The same amount of suction both downwards and to- 

 wards t^e land. Shares in the condition of those 

 shown in Figure 13 are far too common. 



Scouring Qualities of the Plow and Soil. 

 There are many different shaped moidboards for 

 different soils. Right here let me say that unless a 



Figure 13. 



moldboard plow will not scour a disc plow should not 

 be considered. There are districts where the heavy 

 gumbo soil demands disc plows. "Prevention is better 

 than cure" — when you put your plows away next 

 fall smear t^em well with thick oil and they will 

 scour easier when started off the following Spring. 

 Cafe must be taken to see that shares are not warped. 

 If they are, a good joint is not made between the 

 share and the mold board, thus causing trouble. When 

 purchasing a plow pa;<s the finger tips up the mold- 

 hoards in the direction tjmt the furrow slice will 

 pass, and you readily detect rough places. At this 

 point let me quote tlie conclusions arrived at from 

 lests at the Iowa State College (Profe.-^sor J. B. David- 

 son) on t^ie Influence of Speed on the Draft of 

 Plows : 



1. "An increase in the field speed of a plow with 

 a general purpose moldboard from 2 to 3 miles per 

 iiour will result in an increase of draft from 8 to 12 

 per cent- varying with the soil. Doubling the speed 

 will result in an increase of draft of from 16 to 

 25 per cent. The amount of work accomplished is 

 increased from 50 to 100 per cent respectively. 



2. The furrows are laid more smoothly and the 

 furrow slices better pidverized at the higiier speeds. 



3. There are no inherent difficidties in plowing 

 stubble ground in good condition for plowing at a 

 speed of four miles per hour. 



4. It is quite clear from observations made during 

 the tests that plows could be operated at even higher 

 speeds if the plows were specially designed for siieh 

 speeds." 



Note: (This information may be of interest to many 

 who have not seen tiie results of these tes-ts. 

 Many opinions have been expressed. . The 

 facts were noted after very careful and ex- 

 haustive tests. 



Various Adjustments. 

 The adjustment of the hitch will be dealt with later. 

 The rear furrow wheel must be set outside the laud- 

 side of the plow, t^uit is towards the unplowed ground, 

 so that the landsidc will be relieved of some friction. 

 It takes power to overcome friction. Sliding friction 

 requires more power than rolling friction. When 

 plowing four abreast the front furrow wheel must be 



