20 KXPERIMENT STATION EECOKD. (Tol. 88 



treated sample lost 9.7 per cent of its nitrogen, and 68 per cent of its total 

 nitrogen was transformed to ammonium sulphate and held as such. The urine 

 treated with acid phosphate lost only 5 per cent of its nitrogen, and the treat- 

 ment prevented the formation of ammoniacal nitrogen in an open container 

 during the 37-day period of the experiment. After standing in a closed jar 

 three months longer, the acid-phosphate-treated urine was found to be alkaline 

 and evolving ammonia. 



Green manuring, C. Bebnaed (Dcpt. Landb., Nijv. en Handel [Dutch East 

 Indies], Meded. Proefstat. Thee, No. 51 {1916), pp. 34, pis. 10).— Tins is a 

 review and summary of a number of experiments with different leguminous 

 green manures, especially on tea soils of the Dutch East Indies. 



Leguminous crops planted between the rows of tea and used as green 

 manure were in general found to be beneficial, especially if the soil was in poor 

 physical condition. Variable results were obtained with different legumes. 



Soil acidity: The relation of green manures to its development, J. W. 

 White {Pennsylvania Sta. Rpt. 1915, pp. 60-86). — This reports a study of the 

 effect upon soil acidity of adding organic matter, including manure and fresh 

 and air-dry leguminous and nonleguminous crops, to an acid silty loam soil 

 obtained from plats to which ammonium sulphate had been applied for several 

 years. The organic matter was finely ground, thoroughly mixed with the soil, 

 and the mixture placed in jars and freely exposed to the air for a period of 

 nine months, the optimum moisture conditions being maintained in the soil. 



Tabulated data are presented and the results are discussed in detail with 

 reference to changes in the lime requirement of the soil, and the effect of the 

 organic manures upon nitrification, and upon the amount and condition of the 

 humus of the soil under the different treatments. 



It is concluded that " in general, these experiments have satisfactorily shown 

 that fresh green manures plowed under on this acid silty loam soil reduce its 

 acidity very soon after plowing under, but finally leave a soil of increased 

 acidity; also that nitrification goes on in them quite vigorously under suitable 

 moisture, temperature, and aerative conditions, and that the gi'een manured 

 soils are rich in nitrates, despite the soil acidity. As to the cause of the in- 

 creased acidity, beyond showing that it is not largely due to nitrification and 

 indicating that it is in some way associated with the added organic materials 

 or their fermentative residues, the experiments furnished little definite infor- 

 mation." 



Continued studies in acid soil from the ammonium sulphate plats, J. W. 

 White {Pennsylvania Sta. Rpt. 1915, pp. 86-103, pis. S). — A detailed study of 

 variations in lime requirements and nitric nitrogen content of soils from plats 

 which had been fertilized with ammonium sulphate for several years, is re- 

 ported in continuation of work previously noted (E. S. R., 35, p. 514). Addi- 

 tional studies of changes in lime requirements as a result of leaching with 

 water, leaching with absolute alcohol and of storage; nitrification in acid soils 

 on which ammonium sulphate, dried blood, and cottonseed meal were used 

 alone and with limestone; and the relation of humus to lime requirements in 

 various soils. 



On one of the areas studied the lime requirement varied from neutral to the 

 equivalent of 5,277 lbs. of calcium carbonate per acre within a distance of 3 

 ft. Corn failed where the lime requirement was greater than 5,000 lbs. of 

 calcium carbonate per acre to a depth of 7 in. The variation in growth of clover 

 and corn on this area was in close accord with the variation in the lime require- 

 ment. Corn also failed on a plat where the nitric nitrogen was equivalent to 

 8.74 parts per million. Fine dust removed from the surface of this plat showed 



