THIRD ANNUAL YEAR BOOK — PART XI. ()75 



The greatest improvement that has been made in plows is the inven- 

 tion of the disk plow. Last spring the Hancock disk plow was tested on 

 our farms near Des Moines. It was on cornstalk ground and the ground 

 was in fine condition. A machine was used for measuring the actual force 

 used in pulling the plows. The average force registered on common riding 

 plows turning a sixteen-inch furrow was 585 pounds. The disk turned 

 two thirteen-inch furrows, or a total of about twenty-four inches, with a 

 pull of only 500 pounds. The disk plow did one-half more work with less 

 power. 



I have a farm south of town that has a piece of land on it what you 

 would call "gumbo." The disk plow etirred five acres a day as easily as 

 the ordinary plow stirred three acres. The lightness of the draft was mar- 

 velous. The disk plow does not cut a square furrow. The center is about 

 an inch lower than the sides. 



In order to understand why the disk plow pulls so much easier than 

 the ordinary kind it is necessary to know where the tug comes in. In a 

 series of plow tests made at Cornell university ten or fifteen years ago it 

 was found that 35 per cent of the force necessary to pull a plow is used 

 to overcome the friction of the land side and mold board. This is largely 

 avoided in the disk plow, which has neither land side nor mold board. 

 Only 10 per cent of the force is used in pulverizing the ground and 7 per 

 cent in pushing the plow through the ground and dislodging the soil par- 

 ticles. The disk plow does not push its way through, but has a rolling 

 motion like a circular saw. The difference in the way they cut is the same 

 difference you will find in pressing a knife down on a piece of beefsteak 

 and drawing it across in the ordinary way. 



If the mold board of a plow is very sloping the ground is pulverized 

 but very little, being simply turned over. The disks of a disk plow push 

 against the ground at a very steep angle and the scrapers also help in the 

 pulverizing process. We plow mainly for the purpose of pulverizing the 

 soil, which the disk plow does much more thoroughly than any other. It 

 will not work in sod or wet ground. The price is about $55, I believe. 



CLOD CRUSHERS. 



When I was speaking at institutes down in southern Illinois, near 

 Carlinville, what they call "Egypt Land," I found they were using a kind 

 of roller that I am convinced is a splendid implement. I am not a friend 

 of the ordinary roller because it requires so much sense to use it right that 

 it is apt to do more harm than good in the hands of the average farmer. 

 Hard clods are not crushed, but simply pressed into the ground. By com- 

 pressing the surface of the soil the moisture can come to the surface and 

 pass off by evaporation. 



This new roller or clod crusher is built on an entirely different prin- 

 ciple. The work is done by a number of steel disks about twenty inches 

 in diameter and three inches thick in the center and sloping to a thin edge. 

 These disks are set very close together and work independent of each 

 other. The pressure is down below the surface and clods are cut and. 

 ground between these wedge-shaped disks, f believe this is the same tool 



