1917] SOILS FERTILIZEES. 19 



With manganese carbonate much smaller quantities of manganese were ob- 

 tained in solution, even under the action of osyacids. In the tests with man- 

 ganese sulphate, quantities of the salt corresponding to 2, 5, and 50 mg. of 

 manganese were used with 15 gm. of calcium carbonate. With the smallest 

 quantity of manganese, whatever the acid used relatively large amounts of man- 

 ganese passed into solution eight hours from the beginning of acid action. These 

 amounts were largest with citric and malic acids. With 5 and 50 mg. of man- 

 ganese a strong manganese reaction was found even after 36 and 48 hours. 



" Experiments with manganese sulphate and dioxid mixed with eai'th proved 

 that for small quantities of sulphate (2 mg. of manganese to 50 mg. of earth) 

 the treatment with citric and malic acids alone increased the quantity of man- 

 ganese passing into solution, while for relatively large quantities (50 mg. of 

 manganese to 50 gm. of earth) the increase in dissolved manganese was marked 

 on treatment with any acid ; and that for dioxid there was no increase of the 

 manganese dissolved except on treatment with citric and malic acids." 



These results are taken to indicate that compounds of manganese naturally 

 contained in the soil behave in a way similar to that of iron compounds as 

 regards their solubility in acids when lime is in excesss. " The markedly greater 

 capacity of oxyacids for retaining these elements in solution, in spite of the 

 excess of OH occasioned by the acids themselves, is therefore likewise confirmed 

 with regard to the manganese in the soil." 



Soil bacteriolog'y, C. M. Hutchinson (Rpt. Agr. Research Inst, and Col. 

 Pusa, 1915-16, pp. 86-89). — Continuing the work of the previous year (E. S. R., 

 35, p. 626), "a series of field exi^erimental plats under wheat demonstrated 

 the production of infertility in soil containing nitrogenous organic matter (oil 

 cake) as a consequence of semianaerobic conditions artificially induced by water- 

 logging. This infertility did not occur to the same extent when ammonium 

 sulphate was substituted for cake, nor did the effect of the water-logging 

 become apparent until the roots of the plants had gone down some inches to 

 that level in the soil which oxidation consequent on the cultivation had failed 

 to reach. Parallel plats with barley illustrated this effect more markedly than 

 those with wheat. . . . 



" Laboratory work on nitrification and on the growth of seedlings in water 

 and soil cultures demonstrated the possibility of separating substances from 

 certain bacterial cultures, from decomposing organic matter, and from 

 anaerobically incubated soil whose toxicity to nitrlfiers, and in greater concen- 

 tration to seedling plants, was demonstrable under these conditions." 



Observations were made on the interference with the growth of seedlings 

 resulting from the bacterial invasion of the unexhausted and still attached 

 seed, and the consequent absorption by the plant of toxic bacterial by-products 

 showed that this invasion occurred most readily in water -logged soil and more 

 especially in the presence of bacteria derived from anaerobically incubated 

 soils of high organic matter content. Copper sulphate was found to neutralize 

 most of the toxic bodies obtained in this way, and seeds treated with this salt 

 were found to be immunized to some extent, although not entirely or invariably, 

 against this action. 



It was further found that the presence of nitrites in soils is not alone due to 

 the reduction of nitrates already formed, but that in many of the soils examined 

 in the laboratory nitrites accumulate to some extent before nitrate formation 

 becomes evident, even under conditions apparently favorable to nitrification. 

 The concentration of nitrites required to injure various field crops in soils was 

 found in no case to be so great as that required in water cultures. " Weekly 

 borings and nitrate determinations throughout the year v/ere made in three 

 sets of duplicate plats under grass, . . . wheat and maize, and fallow. . . . 



