642 



EXPERIMENT STATION RECORD. 



In plat 2, where clover was grown in rotation and its second crop 

 plowed under for green manure, the soil originally contained 0.221 per 

 cent of nitrogen and at the end of the rotation 0.231 per cent. Larger 

 crops were grown on this plat than on plat 1, and 178 lbs. of nitrogen was 

 removed in the crops, yet there was a gain of 245 lbs. of nitrogen during 

 the 4 years, in addition to the amount removed. "This nitrogen, it is 

 believed, has been gained largely by the clover from the free nitrogen 

 of the air. . . . The value of a good rotation is exemplified in this 

 experiment where the yields per acre have been increased, and at the 

 same time both the humus and the nitrogen have been increased." 



On plat 3 the clover was seeded with oats instead of with wheat as 

 on plat 2. The clover crop, which was rather light, was followed by 

 barley. After the barley crop, this plat received 1,200 lbs. of manure 

 and the next year was seeded to corn, yielding 17 bu. per acre more 

 than plat 4 where corn was grown continuously. 



The soil of plat 4 originally contained 0.211 per cent of nitrogen and, 

 after the 4 corn crops were grown 0.197 per cent, amounting to a loss 

 of 340 lbs. of nitrogen. In the 4 crops 225 lbs. of nitrogen were removed, 

 or nearly 29 lbs. more nitrogen was lost from the soil each year than 

 were removed in the crop. 



During 4 years of continuous oat growing on plat 5 there was an 

 annual loss of 196 lbs. of nitrogen per acre, of which only about 46 lbs. 

 per acre were removed by the crop. The author states that tbe yield 

 has been less affected, although this plat lost its nitrogen more rapidly 

 than plat 1, because the oat plant is a stronger feeding plant than wheat. 



On plat 6 the soil contained 0.211 per cent of nitrogen, and after 4 

 years of continuous barley culture 0.177 per cent, showing a total loss 

 of 800 lbs. of nitrogen. It is reported that about 30 lbs. of nitrogen 

 were annually removed by the crop, and that there was an annual loss 

 of 190 lbs. of nitrogen per acre in addition. 



It is stated that before the rotations there was an average of about 3.30 

 per cent of humus and 7.68 per cent of total volatile matter in the soil. 

 The percentages of humus and volatile matter at the close of the rota- 

 tion periods are given in the following table: 



Loss and gain of humus. 



Plat I Wheat continuously . 



riatll. Rotation 



Plat III. Rotation 



Plat IV. Corn continuously . 

 Plat V. Oats continuously . . . 

 Plat VI. Barley continuously 



Humus. 



Per cent. 

 3.00 

 3.80 

 3.50 

 3.10 

 3.08 

 3.10 



Gain (+) 



or loss 



(-)• 



—0.30 

 + .50 

 + .20 



— .20 



_ 22 



— !20 



Total 

 volatile 

 matter. 



Per cent. 

 7.48 

 8.05 

 7.83 

 7.26 

 7.04 

 6.87 



Gain ( + ) 



or loss 



(-)■ 



—0.20 

 + .37 

 + .15 



— .42 



— .54 



— .81 



With continuous wheat raising an annual loss of 1,800 lbs. of humus 

 per acre, and with the continuous culture of corn, oats, and barley, an 

 annual loss of 1,500 lbs. per acre is reported. 





