Junk, 1920] SOIL SCIENCE 431 



2907. Josm, N. V. Rate of nitrification of different green manures and parts of green 

 manures and the influence of crop residues on nitrification. Agric. Jour. India 14: 396-413. 

 1919. — The paper discusses; what happens to green manure when incorporated in the soil for 

 the coming winter crop, decomposition of different kinds of green manures, decomposition of 

 different parts of green manure — -leaves, stems, roots, effect of the undecomposed tissues or 

 crop residues on the process of nitrification. Three woody plants, sunn-hemp {Crotalaria 

 juncea), dhaincha (Sesbania aculeata) and tamarind (Tamarindus indica) and throe succu- 

 lent plants, guvar (Cyamopsis psoralioides), cow-pea ( Vigna catjang) and gokarn (Cli- 

 torin lernatcn) were chosen for the purpose of the experiment. Green whole plants of the 

 above were cut up and used in pot cultures to determine the rate of nitrate accumulation in 

 the soil. Tamarind plants gave negative results for nitrification, yet decomposition and 

 ammonifi cation had taken place. Rate of nitrification of the succulent plants was in an 

 inverse ratio to the succulence of the stems the more tender and easily decomposed the 

 tissues, the slower the nitrification. Because of the greater amount of oxidizable carbon- 

 aceous material in the succulent tissues, a smaller amount of nitrogenous material is changed 

 into the ammoniacal condition and consequently less nitrification in the succulent plants 

 than in the woody ones in the early stages of decomposition, or putrefactive bacteria attack- 

 ing the succulent tissues multiply so rapidly that they form bacterio-toxins and other dele- 

 terious substances the presence of which may retard the nitrification. Two other alternatives 

 are offered. True denitrification may set in simultaneously with nitrification, due to the 

 great amount of succulent green manures, or further, putrefactive bacteria may assimilate 

 the nitrates formed, for their own growth. In sann-hemp, dhaincha, guvar and cow-peas 

 over 75 per cent of the nitrogen of the plant is contained in the leaves and the stems. Dur- 

 ing the first two months after burial of the green manures, accumulation of nitrates is due to 

 the leaves of the plants and not to stems or roots. It is highly probable that the stems and 

 roots serve as a source of energy for nitrogen fixing bacteria, as Azotobacter , and so ulti- 

 mately prove an indirect source of nitrogen. — F. M. Schertz. 



2938. Plymen, F. J., and D. V. Bol. The biological determination of the relative availa- 

 bility of different nitrogenous organic manures in black cotton soil. Agric. Jour. India 14: 

 414—421. 1919. — The relative availability of the common oil cakes used as manures was 

 determined by studying the rate at which the nitrogen they contain undergoes bacterial 

 transformation. In the black cotton soil of Deccan, koranja (Pongamia glabra), and cotton 

 cakes are the most quickly available, with castor cake (Ricinus communis) a close third. 

 Mahua cake (Bassia latifolia) and sorson cake (Brassica napus) are the slowest to nitrify. — 

 J. J. Skinner. 



CROP FERTILIZATION 



2939. Prizer, J. A. Fertilization of citrus groves during period of high priced fertilizers. 

 California Citrograph 4: 231, 255. 1 fig. 1919.— See Bot. Absts. 3, Entry 2359. 



FERTILIZER RESOURCES 



2940. Burd, J. S. Peat as a manure substitute. Jour. Amer. Peat Soc. 12: 53-62. 1919. 

 — The plant food constituents of peat do not have the same value as those of high grade 

 fertilizers. Peat is not commercially or agriculturally as valuable as farm yard manure. 

 The inoculation of peat is regarded as a useless procedure. — George B. Rigg. 



2941. Hofp, J. N. Peat fertilizer. Jour. Amer. Peat Soc. 12:6. 1919.— U. S. Patent 

 1,261,025, April 2, 1918, covers a method of preparing fertilizer from peat, by treatment with 

 phosphates and subsequent inoculation with bacteria. — George B. Rigg. 



2942. Smit, B. T. Bat Guano. Union South Africa Bull. 15: 1918. The following table 

 shows the percentages of the various constituents in soils, which are compared with two 

 analyses of bat guano. 



BOTANICAL ABSTRACTS, VOL. Ill, NO. 6 



