530 EXPERIMENT STATION RECORD. [Vol. 38 



3.4 tons. The spring-tooth harrow is recommendocl for Iowa conditions, with 

 cultivation after the removal of the second or third cuttings. 



An average yield of 4 tons per acre was reported by 70 farmers using lime, 

 this being 0.6 ton per acre more than the average yield secured by the 1,003 

 farmers who did not apply lime. With applications of lime before seeding the 

 yields averaged 0.2 ton more than in applications after seeding. The Iowa 

 drift, southern Iowa loess, and the Mississippi loess soils are deemed most 

 liliely to be acid. 



Manuring the soil before seeding to alfalfa yielded an average of 3.9 tons 

 per acre for 728 farmers, as compared with 3.4 tons for 502 individuals who 

 did not apply manure. Failures were reported by 14 per cent of those applying 

 manure and by 18.1 per cent of those not applying it. 



An average yield of 3.9 tons was secured from 147 seedings on tiled land, 

 while 3.6 tons was obtained from 795 seedings on land not tiled. There were 

 16.3 per cent failures reported on the tiled ground and 18.8 per cent on the 

 untiled. Higher average yields were secured on the tile-drained fields in all 

 soil areas. 



Cassava experiments, J. de Verteuil {Bui. Dept. Agr. Trinidad and Tobago, 

 16 {1911), No. 1, pp. lS-20) .—Tests with 11 varieties of cassava in 1915 are 

 reported, the Manioc Sellier variety being first with an estimated average yield 

 of 10.16 tons and Mata Lotera last with 2.62 tons. A comparison of plants 

 grown from top, bottom, and middle portions of the sticks resulted in uni- 

 formly higher yields with the middle portions of the three varieties used. Flat 

 planting compared with planting in forked holes 2 ft. square and on banks 

 showed no advantage for the last two methods over the former. Cassava 

 planted with pigeon peas and cotton proved a failure both in the yield of 

 cassava and of the other crops. 



The influence of soil temperature upon seedling' corn, B. D. Halsted and 

 S. A. Waksman {Soil Sci., S {1911), No. 4. pp. 393-398). —Two comparable lots 

 of corn were subjected to different soil temperatures in a greenhouse, namely, 

 the warmth of the seed bed in midsummer, from .July 30 to August 26, and 

 the comparatively cool conditions of the same bed from October 29 to Novem- 

 ber 29 before the fire was started. The soil temperatures were taken at 6 a. m. 

 and 6 p. m., and showed daily averages of 25.68 and 12.83° O. (78.2 and 

 55.1° F.) for the summer and autumn series, respectively. 



The tests involved the factors of texture and size of grain, obtained by the 

 selection of the crosses that carried both starchy and sugary grains on the 

 same ear. The shelled corn was assorted into starchy and sugary grains, and 

 these in turn were separated into the larger and smaller kernels, all defective 

 kernels being discarded. The following sets of grains were planted in duplicate 

 for each series, all units having 250 kernels : Starchy larger, starchy smaller, 

 sugary larger, and sugary smaller. Tabulated data are presented showing the 

 relationship to texture and size of grain, or to soil temperature and texture 

 and size of grain of the following factors : Weight of seed, viability, mesocotyl 

 length, emergence, length of plant, weight of seedlings, vigor of seedlings, and 

 variability in length of seedlings. The observations are briefly summarized as 

 follows : 



The environmental factor of soil temperature is regarded as a controlling one 

 in the growth of seedling corn. Starchy grains of the same ears were 27 per 

 cent larger than sugary grains, 51 per cent more viable, and emerged nearly 

 one day sooner, showing 25 per cent more vigor and 26 per cent le.ss variability. 

 The larger grains of the same ears weighed 29 per cent more than the selected 

 smaller grains, were only 4 per cent more viable, emerged more slowly by 4 



