WATER SOILS. 1063 



" (6) By the use of liberal applications of lime and thorough inoculation with the 

 proper nitrogen-gathering bacteria, clover can be grown on this type of soil with 

 profit. 



"(7) While under certain conditions largely increased yields of oats and of corn 

 have been obtained from the use of potassium, it is still questionable if commercial 

 potassium can be used with profit. 



" (8) Phosphorus is the limiting element in these soils and must be used liberally 

 in order to make them permanently productive. 



"(9) A liberal use of legumes, to supply organic matter and nitrogen, must be 

 an essential part <>f any practical and economical system that ever becomes success- 

 ful in the permanent improvement of southern Illinois soils. 



"(10) It is good farm practice to remove large quantities of plant food from the 

 soil provided as large or larger amounts be returned when necessary." 



Science and sense in the inoculation of legumes, C. G. Hopkins ( Illinois iSta. 

 Circ. 86, pp. 7). — A circular of information regarding this subject. 



Experiments on the accumulation and utilization of atmospheric nitrogen 

 in the soil, E. B. Voorhees and J. G. Lipman ( New Jersey Stas. Bui. 180, pp. 37). — 

 Experiments in boxes containing 160 lbs. of artificial soil which had been used in 

 vegetation experiments during 3 previous seasons are reported, the experiments 

 being so arranged "as to bring out the relation of leguminous crops, such as cowpeas, 

 to the soil nitrogen, and to determine, as far as practicable, the value of this legu- 

 minous crop as a source of nitrogen to subsequent non-leguminous crops. . . . 



"Nitrogenous manures were added or withheld, according to the following plan of 

 study: ( 1 ) The study of the source of nitrogen to cowpeas under the following con- 

 ditions: (a) Without addition of nitrogen, (b) the addition of different amounts of 

 nitrate nitrogen, (c) the addition of different amounts of dried blood nitrogen, (d) 

 the addition of different amounts of ammonia nitrogen in ammonium sulphate, (e) 

 the addition of different amounts - of cow manure nitrogen. (2) The availability of 

 cowpea nitrogen, as compared with nitrate, organic (in dried blood), ammonia, and 

 manure nitrogen for the growth of the non-legumes. (3) The possible accumulation 

 of nitrogen in cultivated but uncropped soils." 



Data are given which show the balance of income and outgo of nitrogen with the 

 different systems of fertilizing under cowpeas and a succeeding crop of millet, as well 

 as the availability of the nitrogenous materials applied to the different boxes. The 

 results show that with two exceptions there was a gain of soil nitrogen under all of 

 the conditions of these experiments. The cowpeas converted the soluble soil and 

 fertilizer nitrogen as well as atmospheric nitrogen into insoluble proteid nitrogen 

 which the. subsequent crop of millet secured through a complicated series of bacterial 

 changes. There were evidently some losses of nitrogen from the soil, but " by some 

 process or processes in the soil itself, the loss of nitrogen was more than made up by 

 the formation in the soil of nitrogen compounds at the expense of the free nitrogen 

 of the atmosphere." It is estimated that the average gains noted in these experi- 

 ments approximate an increase of one-third in the nitrogen during two growing 

 seasons. 



"Assuming the nitrogen content of a fair arable soil to be 5,000 lbs. per acre to a 

 depth of 1 ft., an increase by one-third of this amount would mean more than 1,600 

 lbs. of nitrogen per acre, and that in the course of only two short growing seasons. 

 Further comparison reveals the fact that the fixation was greatest in the series where 

 the greatest amount of manure was applied, and that the next greatest amount of 

 nitrogen occurred in the series where the smaller quantity of manure was applied. 

 Furthermore, the final gains thus secured represent an amount less than that actually 

 present, for there probably was a more or less extensive volatilization of nitrogen 

 from these soils in the course of decay." 



