816 EXPEKIMENT STATION RECORD. [Vol.36 



The influence of various cations upon the rate of absorption of ammonium 

 Ion by soil, K. Miyake (Soil Sci., 2 {1916), No. 6, pp. 5 S3-5 88) .—From a study 

 of the mechanism of absorption of the ammonium ion by a loam soil, the author 

 draws the following conclusions : 



" The relation between the time which a solution of ammonium chlorld has 

 remained in contact with soil and the amount of ammonia absorbed by the 

 soil is expressed by the equation x—Kt^ even in the presence of another chlorld 

 in solution. The presence of other chlorids decreases the rate of absorption of 

 ammonia from ammonium chlorld solution by the soil. The retardation in- 

 creases with the concentration of salt employed. Salts differ in their power of 

 causing retardation of the rate of absorption of ammonia. The retarding effect 

 of the salts employed increases in the following order: Na<Mg<Ca<Al<K. 

 The value of Km, which we term the coefficient of absorption in this case, de- 

 creases with increasing concentrations of the salts, the acceleration of the 

 decrease being positive in the cases of NaCl, MgClj, and CaGlj, and negative in 

 the cases of AlCU and KCl." 



A list of references to literature bearing on the subject is given. 



Effect of irrigation water and manure on the nitrates and total soluble 

 salts of the soil, F. S. Habris and N. I. Butt (V. S. Dept. Agr,, Jour. Agr. 

 Research, 8 (1917), No. 9, pp. SSS-S59, figs. iS).— Experiments were conducted 

 at the Utah Experiment Station to determine the effect of varying quantities 

 of soil moisture and maniu-e on the total soluble salts and nitrates that can 

 be extracted by water from soil kept in the laboratory, soil liept for long 

 periods in large tanlis, and normal field soil. Comparisons were also made of 

 cropped with uncropped soils in tanks and in the field. 



It was found that " with a sod soil held in the laboi'atory for 2.5 years, the 

 total salts and nitrates accumulated most rapidly with a moisture content 

 between 23 and 28 per cent. Cropped and uncropped soil kept in large tanks 

 under controlled moisture conditions showed a decrease In nitrates and total 

 soluble salts as the percentage of moisture increased, the nitrates being par- 

 ticularly low in water-logged soil. Under field conditions more nitrates were 

 found in both cropped and fallow soils during the summer than just after the 

 corn crop was harvested. 



"The nitrates of the fallow field soils averaged higher with a manuring of 

 either 5 or 15 tons to the acre than with no manure, but on the cropped soil, 

 although the 15-ton application of manure resulted in more nitrates than no 

 manure, the 5-ton did not. The fallow soil showed the effect of the manure 

 on the nitrates more in the top 2 or 3 ft than at lower depths. 



" The highest soluble-salt content of fallow soil was on plats manured at 

 the rate of 5 tons to the acre ; the lowest was on plats receiving 15 tons. The 

 corresponding high and low points in cropped soil were on plats receiving no 

 manure and 5 tons to the acre, respectively. 



" Unirrigated land contained more nitrates than irrigated on both cropped 

 and uncropped plats. Increasing the irrigation water applied to the soil de- 

 creased its nitrate content. The total soluble salts In cropped plats decreased 

 as the water applied increased, and in fallow soil an application of 40 in. of 

 water resulted in less salts than where no irrigation water was added. The 

 treatment affected the salts more in the surface foot than at greater depths 

 VTith small irrigations, but when 20 In. of water or more were applied some of 

 the salts seemed to have moved below 10 ft. in depth. Large Irrigations 

 decreased the soluble salts in cropped more rapidly than it did in fallow soils. 



" Manuring or Irrigating the soil affected the nitrates relatively more than 

 the total salts. In unmanur^d soil the nitrate content was about twice as great 

 with a fallow as with a crop and in manured it was about three times as great. 



