FIELD CEOPS. 853 



the manure taken from the barnyard. The authors beUeve that with a lighter appH- 

 catiou a larger percentage of the nitrogen in the deep stall manure would have been 

 utilized. 



In another series of experiments it was found that liquid manure or nitrate of soda 

 gave a larger increase in yield on soil poor in nitrogen when applied alone than when 

 used with either a mixture of fresh manure and straw or with straw alone. When 

 liquid manure or nitrate was applied alone a larger jiercentage of the nitrogen fur- 

 nished was recovered in the crop than in the other case. This is explained by refer- 

 ence to the fact that fresh organic substances, such as the manure and the straw in 

 this case, serve as a food material for certain soil bacteria and withdraw the nitrogen, 

 which is in the form of nitrates, ammonia, and amids, from the use of the plants. 

 This action necessarily results in a diminished yield on soils not containing an ade- 

 (piate amount of available nitrogen. These experiments were conducted in the first 

 place with mustard, a very quickly growing plant, but later the same results, though 

 not so marked, were obtained with cereals. The residual effect of the manure for 

 the second and third years was only slightly favorable, while straw still had a detri- 

 mental effect the second and gave but a very slight increase in yield the third year. 

 Fresh manure and straw did not decrease the yield on soils which furnished suffi- 

 cient nitrogen for both the growing crop and the denitrifying bacteria which live on 

 the nndecomposed material. It sometimes occurs that when nitrogen is plentiful 

 the use of fresh manure and straw increases the yield through its beneficial mechan- 

 ical effect on the soil. It was also found that plants will take up as much nitrogen 

 from nitrate of soda applied with barnyard manure, especially if well rotted, as when 

 the nitrate is given alone, because the denitrifying organisms use the nitrogen com- 

 pounds already formed in the manure. The authors conclude that the best yields of 

 root crops are obtained when barnyard nianure is used, but these results are not 

 contradictory to the foregoing, because in these tests a surplus of available nitrogen 

 existed in the soil and the barnyard manure used was not fresh. However, if the 

 nitrogen supply of the soil had not been sufficient, then the use of fresh manure 

 would also have been detrimental to roots. 



Among different green manures a mixture of beans, peas, and vetches was most 

 effective. The seed of this mixture, consisting of 50 per cent of beans, and 25 per 

 cent each of peas and vetches, was sown after early barley or with winter oats at the 

 rate of 250 kg. per hectare. The average annual financial returns per hectare from 

 this method of green manuring amounted to $15. The quality of sugar beets was 

 slightly lowered by green manuring. All nitrogenous fertilizers tend to lower the 

 quality of l)eets and potatoes, but this loss is said to be largely outweighed by the 

 increase in yield, provided the application is not too heavy. 



A number of check plats which received no nitrogen gave good returns and showed 

 no decrease in yields during the several years the experiments were in progress. 

 This result shows that the soil conditions did not allow heavy applications of nitro- 

 gen. On sugar beet and potato plats, fertiliz»-d at the rate of 2 cwt. each of nitrate 

 of soda and 200 cwt. and 133 cwt. of barnyard manure, respectively, i of the nitrate 

 was a]>i)lied at a loss. In experiments with wheat on plats of this same kind of soil 

 which liad not received barnyard manure for 2 years, only h and | cwt. of sulphate 

 of ammonia per morgen (about.0.6 acre), applied in the fall and spring, respectively, 

 was profitable. Where the preceding crop of potatoes had received barnyard 

 manure only 5 cwt. in the spring in addition to the 2 cwt. given in the fall gave a 

 profitable return. Barley on this soil without barnyard manure for 2 years used 

 only from i to | cwt. of ammonia per morgen with profit. It was found that where 

 the preceding crop of beets had received barnyard manure, Ijarley needed no api:)li- 

 cation of nitrogen. 



The use of phosjihoric acid was necessary in all cases. An application of 20 to 25 

 lbs. per morgen for cereals and of 25 to 30 lbs. for root crops is considered adequate. 



