1918.1 FIELD CROPS. 825 



A study of the effect upon the profitableness of farming of different amounts 

 of idle land in summer fallow indicated that the interest on investments varied 

 from 5.9 per cent on farms having 46.5 per cent of the rotation area in summer 

 fallow to 8.3 per cent for those having only 6.4 per cent of the area idle, with 

 respective labor incomes of —$200 and $490. With respect to the per-acre yiol.5 

 of crops, the interest on investments varied from 5.5 per cent for an average 

 crop index (crop yield as compared with average of all farms taken as 100) of 

 79 to 8.2 per cent for a crop index of 122, with labor incomes of —$220 and $480, 

 respectively. It is concluded, therefore, " that any cropping system which either 

 will increase yields or reduce the amount of land devoted to summer fallow 

 without decreasing the crop yields will materially increase farm profits on these 

 farms." 



The effect on crop yields of eliminating summer fallow is noted as indicated 

 by a farm survey made in 1912 on 144 silt loam soil farms in the Willamette 

 Valley, Oreg. The crop index for farms without summer fallow was found to 

 be 101, as compared with 96 for farms with summer fallow, wheat being the 

 only crop to produce more per acre with summer fallow than without it. The 

 introduction of legumes, principally clover, into the rotation was regarded as 

 the determining factor in these results, the crop index ranging from 82.8 for 

 farms with no legumes to 111.4 for those with 44.8 per cent of the crop area in 

 legumes. In a study of the field crop area in clover in relation to farm profits 

 and yields, the average labor incomes varied from — $1.35 to $560, and the crop 

 index from 95.8 to 110.7, for farms with no clover and those with 32.7 per cent 

 of the field crop area in clover, respectively. 



Clover seeded with four different nurse crops produced a successful stand 

 on 75.9 per cent of the area seeded in winter wheat, on 96.5 per cent of that 

 seeded in spring wheat, on 89.7 per cent of that seeded in oats, and on 97.8 per 

 cent of that .seeded in barley. The principal factors contributing to the failure 

 of clover seeded with a nurse crop are said to be foul land, poor seedbed prepa- 

 ration, too thick seeding of the nur.se crop, poor seed, late seeding, and lack of 

 proper soil inoculation. The pure culture and the field soil methods of inocu- 

 lating clover are briefly described, and the production of clover for seed is dis- 

 cussed. 



Crop rotation investigations. — Field T experiments, A. C. Akny (Minnesota 

 Sta. Bui. no {1911), pp. 3-55, figs. 3). — This reports the results of crop rotation 

 experiments extending over a period of six years, 1909 to 1914, inclusive, and 

 embracing a study of different cropping systems, tests of commercial fertilizers 

 in addition to barnyard manure for good rotations, and observance of methods 

 (if tillage and manuring. Rotations of 2, 3, 4, 5, and 7 years' duration were 

 inaugurated, employing wheat, oats, corn, potatoes, flax, and timothy and clover 

 lor hay and pasture, and are compared with continuous cropping schemes, in- 

 cluding oats, wheat, oats and wheat mixed, corn, and mangels. With certain 

 exceptions, manure has been applied to each rotation and cropping system at the 

 rate of 2 tons per acre per year. The fertilizer experiments were conducted on 

 a standard 3-year rotation of oats, clover for hay, and corn, and included tests 

 of complete commercial fertilizers, used with and without manure, and of raw 

 rock phosphate, acid phosphate, muriate of potash, and nitrate of .soda \ised 

 singly with 6 tons of manure per acre. The same standard rotation was em- 

 Iiloyed for the tillage and manure experiments, and the usual method of tillage, 

 fall plowing the meadow for corn, and double di.sking corn land for oats, was 

 adopted as a standard and compared with spring plowing for corn and fall and 

 spring plowing for oats. Observations were also made of rotations without 

 manure, of manure applied to the meadow, of pasturing off the grass, and of 



