214 EXPERIMENT STATION RECORD. 



experiments with poudrette prepared in different ways in comparison with 

 barnyard manure, oil calce, and sewage effluents of different Ivinds are reported. 



It is stated tliat " of all the systems employed for the manufacture of 

 poudrctte, the one in which the night soil and town sweepings are mixed with 

 a top layer of earth for weighting down the whole mass appears to be the 

 best suited for adoption by the municipalities where the question of disposing 

 of both these substances in quantities is important." 



Analyses of poudrettes prepared by different processes are reported, showing 

 nitrogen varying from 0.8 to 1.6S per cent, phosphoric acid from 1.57 to 4.1 

 per cent, and potash from 2.22 to 5.33 per cent, with a moisture content ranging 

 from 4.64 to 13.79 per cent. 



In experime"nts on corn, sorghum, sugar cane, guinea grass, alfalfa, and other 

 forage plants, poudrette proved more effective than barnyard manure. The 

 residual effect of the poudrette was observed 10 years after application. 



[Experiments with night soil], T. F. Main (Ann. Rpt. Dept. Agr. Bonibay, 

 1909-10, pp. 31, 32). — Good results from direct applications of night soil to 

 cotton and from its after effects on succeeding crops for 6 years are reported. 

 It was more effective, prompt in action, and profitable than barnyard manure. 



SOILS— FEETILIZERS. 



A wax seal method for determining the lower limit of available soil 

 moisture, L. J. Braces and H. L. Shantz {Bot. Gaz., 51 {1911), No. 3, pp. 210- 

 219, figs. 2). — The method proposed "consists in growing the plants in a small 

 glass pot, evaporation from the soil surface being prevented by means of a 

 seal of wax which is melted and flowed over the soil surface. In the case of 

 monocotyledons, this wax seal can be applied immediately after planting the 

 seeds, and the seedlings will grow readily through the wax, forming a perfect 

 seal around the stems. In the case of dicotyledons, the wax, which is usually 

 a mixture of paraffin and vaseline having a low melting point and low heat 

 conductivity, can be melted and flowed around the stems of the seedlings with- 

 out injury. During gi'owth, the pots are kept immersed in a water bath to 

 avoid condensation of the soil moisture on the pot walls." 



The water in this bath is stirred constantly to keep the temperature uniform, 

 and a temperature of about 70° and a relative humidity of about 85 per cent 

 are maintained. The amount of water added to the soil at the beginning 

 depends upon the texture and will vary from 5 per cent for sand to 30 per cent 

 for clay. As soon as the plants show unmistakable signs of wilting the moisture 

 in the soil in the pots is determined and this is taken as a measure of the non- 

 available soil water. 



Tests of the method with Kubanka wheat seedlings indicate that " the 

 probable error of the mean of the determinations from 12 pots or more does 

 not usually exceed 0.1 per cent of actual soil moisture, which is fully com- 

 parable to the accuracy with which the soil itself can be defined through its 

 physical projierties." 



In these tests the mean nonavailable moisture was 2.59 per cent in fine sand, 

 O.GG per cent in fine sandy loam, and 16.3 iier cent in clay loam. The method 

 is stated to be particularly adapted to the study of transpiration. 



Contributions to our knowledge of soil fertility, I, R. Greig-Smith (Proc. 

 Linn. 8oc. N. S. Wales, 35 {1910), pt. If, pp. 808-822B) .—In these investigations 

 the author found, by means of cultures of pacillus prodigiosus in soil extracts 

 filtered through paper and porcelain filters, that bacteriotoxins were unques- 

 tionably present in the soils experimented with and that these either killed 

 or restricted the growth of bacteria which had been added to the extracts. 



