424 



EXPEEIMEN'T STATION BECOED. 



rVoL37 



at the rate of 1.3312 gm. per kilogram. In the second series part of the soil was 

 treated with chloroform at the rate of 50 cc. per kilogram. The results are 

 given in the following table : 



Fixation of phosphoric acid soluble in water in percentages of the quantity 

 added to the soil (1.3312 gm. of Pt O, per kilogram). 



Treatment. 



Layer 9 to 17.7 cm. 



April 

 fallow. 



Uncul- 

 tivated 

 land. 



Kitchen 



garden 



soil. 



Forest 

 soil. 



Layer 17.7 to 35.5 cm. 



April 

 laliow. 



Uncul- 

 tivated 

 land. 



Kitchen 



garden 



soli. 



Forest 

 sou. 



First series: 



Total fixation (with potassium 

 nitrate) 



Total fixation (without potas- 

 sium nitrate) 



Second series: 



Total fixation (in chloroformed 

 soil) 



Phvsico-chemical fixation (in 

 cnloroformed soil) 



Biological fixation 



Perd. 



87. M 



87.14 



84.90 

 2.24 



Perd. 

 87.93 

 84.04 



84.04 



81.92 

 2.12 



Perd. 



Perct. 



84.06 



82.58 

 1.48 



75.28 



73.16 

 2.12 



Per a. 

 92.56 

 9L64 



91.64 



89.94 

 1.70 



Per a. 

 89.87 

 86.92 



86.92 



86.05 

 .87 



Perd. 



84.11 



83.29 

 .82 



Perd. 



83.65 

 .22 



It is concluded that the process of lixation of water-soluble phosphoric acid 

 in soil depends on physical, chemical, and biological factors, and that the 

 intensity of the total fixation is In direct relation to the cultural conditions 

 and Increases with the addition of potassium nitrate to the soil. Fixation was 

 greater in natural soils than in chloroformed soils. The total fixation and 

 the phjsiciil and chemical fixation were le.s.s In the arable layer, to 17.7 cm., 

 than in that lying immediately beneath, from 17.7 to 35.5 cm. 



Further experiments with the bacterial flora of each of the soil samples 

 capable of multiplying in peptonized meat bouillon led to the deduction that the 

 quantity of these bacteria Increased with the improvement of the cultural 

 conditions of the soil. 



The gases of swamp rice soils. — IV, The source of the gaseous soil nitro- 

 gen, W. H. Harrison and P. A. Subramania Aiyeb (iletn. Dept. Agr. India, 

 Chem. Scr., 5 {1916), No. 1, pp. 1-Sl, pis. 6, fig. 1). — Continuing previous ex- 

 periments (E. S. R., 36. p. 116), "it has been demonstrate*! that a very consid- 

 erable proportion of the gaseous nitrogen normally found in swamp paddy 

 soils Is produced through the decomposition of organic matter. . . . The nitro- 

 gen gas thus liberated is derived from two distinct sources, namely, (1) from 

 the decomposable organic matter of the soil or of the green manure used, 

 and (2) from a certain proportion of the roots of the crop which die and sub- 

 sequently decompose. The production of gaseous nitrogen from soil organic 

 matter and green manure persists throughout the growing season but Is most 

 prominent during the earlier period, whereas that derived from root decom- 

 iwsltion Is most prominent during the later stages of growth and persists after 

 harvest time. 



" There Is no evidence forthcoming to show that the crop Interferes with, 

 or materially niters, the normal course of the fermentation of the soil organic 

 matter and green manure; In fact the balance of evidence Is distinctly against 

 this theory. Under normal conditions in uncrnpped soils the nitrogen gas thus 

 producetl escapes from the .soil Into the air at a fairly uniform rate. On the 

 other hand, that producetl in cropped soils does not escape in any quantity 

 until about the time when the plant is running up for flower. At this stage 

 a very marked escape of gas occurs which continues up to and past harvest 



