480 EXPERIMENT STATION RECORD. [Vol.43 



concentrated sewage be mixed with an equal volume of beet-carrying water, 

 tlie data indicate that a settled effluent could be treated on sand filters dosed 

 at the rate of 100,000 gal. per acre per 24 hours. 



" These rates of filtration result in quite co.stly installations, and every 

 effort should be made to keep the cost down by utilizing local conditions of 

 stream flow and soil to the utmost. These results are not wholly conclusive, 

 but indicate the great difficulty of treating beet sugar plant .sewage." 



Utilization of war explosives in industry and agriculture, G. Gakiboldi 

 (Gior. Chim. Indtis., 2 (1920), No. 1, pp. 10-22, figs. 9). — Data are reported on 

 experiments conducted in different parts of Italy on the use of ballistite, 

 T. N. T., and picric acid for the blasting of rocks and especially for soil 

 blasting. « 



The ballistite appears to be a lower velocity explosive than T. N. T. or 

 picric acid and is better adapted for damp soil blasting, while the T. N. T. 

 and picric acid are better adapted for dry, hard soil and rock blasting. The 

 ballistite is apparently not sensitive to moisture, and may be exploded under 

 water as effectively as an equal amount of dynamite. In dry, hard, rocky 

 soils the picric acid demonstrated its superiority to the other two explosives. 

 However, picric acid and T. N. T. were found to be effective in humid soils 

 also. 



Utilization of dynamite in agriculture, F. A. Kuhn {Hacienda, 1^ (1919), 

 No. 11, pp. 322-329, figs. 14). — Practical data on the use of dynamite for stump 

 removal, ditch digging, subsoiling, tree planting, and rock blasting are given. 



Forced v. delayed systems of clearing stump land, M. J. Thompson (MIji- 

 nesota Sta. Bui. 189 (1920), pp. 5-24, figs. ^6).— This bulletin supplements Bul- 

 letin 163 of the station (E. S. R., 36, p. 785), reporting the progress of stump- 

 clearing experiments on tract 3, and includes miscellaneous data related to the 

 general subject of land clearing. 



• Tract 3 was sown in the spring of 1914 to clover and grass at the rate of about 

 2 lbs. alsike clover, J lb. red clover, and 2i lbs. mixed grasses per acre. The 

 land was prepared before and after seeding by stirring with one section of 

 a spring-toothed harrow drawn by one horse, and covering as much ground as 

 possible between the stumps. It was lightly pastured during the season of 

 1914 and pastured through the seasons of 1915-191S. Removal of stumps was 

 begun in 1918, and stumping and plowing was completed in 1919. Two-thirds 

 of the stumps were pulled by horsepower direct without dynamite or machine. 

 The stumps not thus pulled averaged 13.17 in. in base diameter. The value of 

 dynamite and accessories thus displaced averaged about .*!^5 per acre. 



The cost of clearing ripe stumps per acre using dynamite was $55.31 in 1918 

 as compared to $51.64 with green stumps in 1914. This was an increase of 

 7.1 per cent, due to increased costs of labor and material, as on the basis of 

 costs in 1914 the 1918 cost of clearing ripe stumps would have been $37.72, or 

 36.7 per cent less than the 1914 cost of green blasting. The cost of clearing 

 an acre of ripe stumps in 1918 using the stump-puller was $44.08, a saving of 

 $14.96, or 33.9 per cent, on the cost of removing an acre of green stumps by 

 machine power in 1914. On the basis of 1914 costs of labor and material, the 

 1918 cost would have been $31.81, and the saving 46 per cent. 



Stump-puller clearing cost more than dynamite clearing in 1914, but in clearing 

 ripe stumps In 1917 it was lower than all other prices for either year. It cost 

 as much to blast, pull, and pile one large decayed stump as to pull and pile 10 

 small ones by horsepower. It cost as much to pull and pile one stump by ma- 

 chine power as it did to pull and pile three by horsepower. 



In 1915 clearing operation receipts exceeded costs of clearing up to the 

 stump stage, with a surplus credit of pole and slab wood, and sawdust for bed- 



