128 EXPERIMENT STATION RECORD. 



ammonifying organisms have very different effects upon tlie nitrifying jorgan- 

 isms, the soil from acid plats especially inhibiting their functions to a consider- 

 able extent, though not wholly suspending them." 



The nitrification investigations are being continued. 



Some results of thirty years' soil treatment with barnyard manure, W. H. 

 MclNTiKE (Penmylrania Sta. Rpt. 1912, pp. 51-G3). — Field experiments with 

 corn, oats, wheat, and hay on a clay loam soil of limestome origin, described 

 in a previous report (E. S. R., 20, p. 1017), to determine the effect on soil and 

 crop of barnyard manure applied in amounts of 6, 8, and 10 tons per acre, and 

 of 6 tons of manure supplemented by 2 tons of lime applied only to corn, are 

 reported. 



The largest returns per ton of manure were secured from plats receiving 6 

 tons of manure and the smallest from those receiving 10 tons. The addition of 

 2 tons of burnt lime once in four years caused the yield resulting from the appli- 

 cation of 6 tons of manure to approximate the yield from 10 tons and lessened 

 the accumulation of humus in the soil. The accumulation of organic matter 

 was greatest upon plats receiving G tons of manure and least on those receiving 

 10 tons. 



The soil under mature clover was richest in organic matter, followed in order 

 by soil under young clover, soil containing clover residues, and soil under oats. 

 The soil under mature clover had the highest nitrogen content, followed in order 

 by the soil containing clover residues, soil under young clover, and soil under 

 oats. 



Liming, in addition to manure, increased the accumulation of nitrogen in the 

 soil, the greatest nitrogen accumulation being with the 8-ton application and 

 the least with the 10-ton application. The gi-eatest occurrence of nitrate was 

 observed in the limed soil under corn, followed in order by gi-ass soil, wheat 

 stubble soil, and oat stubble soil. The soils receiving 6 and 10 tons of manure 

 were practically identical as regards nitrate content, while the soil receiving 8 

 tons of manure had the smallest nitrate content. 



Summary of the results obtained from experiments with commercial 

 fertilizers, yard manure, lime, etc., extending through a period of thirty 

 years, T. F. Hunt, F. D. Gardner, and C. F. Noll {Pcnnsylvaniu Sta. Rpt. 

 1912, pp. 83-119, pi. 1, figs. 6). — This report gives the detaileii results of the 

 last 5 years of a series of 30 years' fertilizer experiments on a clay loam soil, 

 the first 25 years' results of which liave been previously noted (E. S. R., 21, 

 p. 220), and summarizes the more salient facts brought out by the 30 years' 

 work. The crops were corn, wheat, oats, and grass. The main results of the 

 30 years' work are as follows : 



The application of potash and nitrogen singly had no material effect upon 

 crop yield, while phosphoric acid when applied alone had a distinct influence 

 in maintaining the productiveness of the soil. In spite of the beneficial results 

 given by phosphoric acid, the results as a whole indicate that it is a poor 

 practice to apply a single fertilizer continuously to this soil. Complete fertiliza- 

 tion gave an increased crop yield dui'iiig 30 years of 55.2 per cent. " When 

 potash was applied alone no increase resulted. When applied with phosphoric 

 acid a material increase resulted over the application of phosphoric acid alone. 

 In like manner, but in less marked degree, owing to bacterial agencies supplying 

 nitrogen, when nitrogen was applied with phosphoric acid or potash or with 

 both, increased yields resulted." 



Sodium nitrate as a source of nitrogen almost without exception gave better 

 results than cither dried blood or ammonium sulphate during the 30 years. The 

 sodium nitrate and dried blood wore as effective the last 5 years as during 



