1919] FIELD CROPS. 623 



tenance of soil fertility, protection against Hoods, the rational utilization of 

 water in arid regions, and the proper use of fertilizer materials. 



Field technique in determining yields of plats of grain by the rod-row 

 method, A. C. Arny and R. J. GABBEB (Jour. Aim r. Soc. Agron., 11 (1919), No. 

 1, pp. 83-47, figs. 2). — This paper, B contribution from the Minnesota Experi- 

 ment Station) describee observations made as to the precision secured in de- 

 tenninlng yields by the removal of 9, 5, and 4 rod rows from tenth-acre plats 

 as compared with harvesting and threshing the entire plats, and on the com- 

 parative labor requirements of the two methods. The data were obtained from 

 triplicated and variously treated fertilizer plats sown to wheat and oats on 

 University Farm, to wheat on the Morris substation, and to oats on the Duluth 

 substation. 



In a comparison of yields to determine the value of fertilizer treatments, 

 it is stated that increases over the mean of the checks of 15.7 per cent for 

 triplicate tenth-acre plats, 9.49 per cent for 9 rod rows, 12.73 per cent for 5 

 rod rows, and 14.44 per cent for 4 rod rows removed from 3 similarly treated 

 tenth-acre plars are probably significant. On the Duluth substation, however, 

 increases over the checks of 32.4 per cent for tenth-acre plats and 12.34, 16.56, 

 and 18.51 per cent, respectively, for 9, 5, and 4 rod rows appeared to be necessary 

 if the differences were to be attributed to the fertilizer treatments. Variations 

 in the results secured with the methods on the different experimental fields are 

 noted, and the conclusion reached that the removal cf 9 rod rows from tenth- 

 acre plats gave practically as accurate an indication of the value of the different 

 fertilizer treatments as harvesting the entire plat. The amount of man labor 

 required by the two methods was found to be about the same. 



The practical value of line selection with field crops, L. Koch (Teysmannia, 

 29 (1918), Nos. J, pp. 1-86; 2, pp. 96-127; 3, pp. 165-191) .—The author de- 

 scribes observations made with selections of peanuts, rice, corn, and soy beans, 

 the results of which have been subjected to a statistical analysis in an attempt 

 to demonstrate the value of this practice in the improvement of these crops. 



The influence of crop plants on those which follow, I, R. L. Hartwell and 

 S. C. Damon (Rhode Island Sta. Bui. 175 (1918), pp. SO, pi 1, fig. 2).— This 

 bulletin describes held work begun in 1907 and previously mentioned (E. S. R., 

 40, p. 135) in which observations have been made of the effect of different 

 crops upon the following crop. The general plan of the experiment was to grow 

 without farm manures upon contiguous 2/15th acre plats, onions, potatoes, 

 mangels, rutabagas, cabbage, buckwheat, corn, millet, oats, timothy and redtop, 

 redtop, timothy, squash, alsike clover, and red clover, respectively, for two 

 successive years, and one of these crops every third year over the entire area. 

 Fertilizer chemicals were applied to all plats alike in amounts intended to 

 supply an average of the nutrient needs of the different crops, information re- 

 garding which was obtained from soil tests made in pots in the greenhouse 

 and in sections of drain pipe sunk In the paths between the field plats. Onions 

 occupied the entire area In 1910, buckwheat in 1913. and alsike clover in 1916 

 and again in 1917. The results obtained may be summarized as follows: 



Arranging the preceding crops in the order of increasing yields of onions, 

 from 13 to 17 bu. were produced following cabbage, mangels, rutabagas, and 

 buckwheat; 35 and S7 bu., respectively, following potatoes and rye; from 131 

 to 178 bu. following corn, millet, onions, oats, and red clover; from 240 to 314 

 bu. following squash, timothy, and alsike clover ; and 406 and 412 bu., re- 

 spectively, after mixed timothy and redtop, and redtop alone. 



Following the same arrangement with regard to buckwheat, yields of from 

 4 to 10 bu. were produced after millet, grasses, corn, and the clovers; 13 and 



