THE ROTATION OF CROPS 4" 



spot disease (Cercospora beticola) was prevalent. In 1901 the crop 

 was sown on these and on plats which had been in corn in 1903 and 

 other crops previously. The disease attacked the beets on the " no 

 rotation " plats early in the season, and many rows had to be resown. 

 The yield per acre was 9.5 tons containing one ton of dry matter, 

 value $20. The yield per acre on the rotation plats was 33y 2 tons 

 containing four tons of dry matter, value $80, a clear gain of $60 per 

 acre from the rotation of crops. 



Different crops require different amounts of water to make a pound 

 of dry matter, that is, some transpire more than others, thus oats 

 will transpire 500 pounds, potatoes and corn about 300 pounds, barley 

 about 100 and clover frequently over 600 pounds. From this it will 

 be seen that the Maine farmer is wise because he is discounting the 

 season, when he sows oats the year after potatoes in his rotation of 

 clover (two years), potatoes, oats; thus a light water consumer is 

 placed between two heavy consumers. This is important since water 

 is generally the factor which controls the yield of crops. At Eoth- 

 amsted, England, where wheat has been grown for 60 years on the 

 same piece of land without manure or fertilizer, the average yield per 

 acre is about 12y 2 bushels, while on land in a rotation — but otherwise 

 similarly treated — the average yield was about 26 bushels. During 

 the last 52 years the total yield of wheat is 665 bushels, which at 

 75 cents per pushel is worth $198.75. That of continuous barley 

 growing, also without manure or fertilizer, during the same time, was 

 868 bushels worth $131 at 50 cents a bushel. When wheat and barley 

 were grown in rotation with roots and clover or beans, without manure 

 or fertilizers, the yields and values of the 13 crops of each were roots 

 9.5 tons, $19; barley 333 bushels, $166.50; clover (5 crops) 1.12 tons, 

 $44.20; beans (8 crops) 101 bushels, $101; wheat, 335 bushels, $251.25; 

 a total of $591.95. 



The income from the land under this system is in favor of the 

 rotation. It is $96.20 or 19 per cent, ahead of continuous wheat farm- 

 ing and $150.95 or 31.75 per cent, ahead of continuous barley farming. 



Scientists have been kept busy explaining why we should get better 

 yields from a rotation of crops. De Candolle over 100 years ago 

 suggested that plants excreted a poisonous substance which rendered 

 the soil objectionable to others of the same species, a theory which is 

 again coming into some prominence. The continuous culture of wheat 

 and barley at Eothamsted was undertaken partly to test this. Experi- 

 ments now being conducted at Woburn Fruit Station, England, show 

 that grass injures fruit trees, and it is claimed that the injury seems 

 to be due to some poisonous substance, either direct or due to bacteria. 

 Liebig suggested that plants tended to exhaust the soil by the removal 

 of different ingredients and that as some plants took more of one in- 



