1919] FIELD CROPS. 139 



Johnson grass eradication ; irrigation experiments witli alfalfa ; irrigation, cul- 

 tural, and manurial tests with potatoes; and trials with Giant Russian sun- 

 flowers for forage. 



Medium deep plowing on soils free from an excess of moisture is said to have 

 resulted in a material decrease in the stand of Johnson grass, while plowing 

 wet soil served to stimulate it. San Luis Valley peas and wheat gave good 

 results as smother crops. 



Giant Russian sunflowers seeded in rows and cultivated the same as corn 

 produced at the rate of 25 tons of silage per acre when cut in full bloom. It is 

 stated that the crop is of doubtful value as a seed crop owing to ravages from 

 birds. 



The alfalfa plats receiving 5-in. applications of water and cultivated once 

 after each irrigation produced the heaviest yields in 1917, followed closely by 

 plats seeded broadcast receiving the same amount of water. Two-in. applica- 

 tions produced the greatest amount of hay per inch of water, 333 lbs., as 

 compared with 285.7 lbs. for the 5-in. application. Observations made in root 

 penetration again indicated that alfalfa roots increase in length with an 

 increase in the amount of water applied. 



A tabular statement is presented showing the potato yields for individual 

 plats, together with a diagram of the plat an-angement and a graphic repre- 

 sentation of the results secured during 1918. Plats receiving no winter irriga- 

 tion but 1, 2, and 3 summer irrigations produced at the rate of 2,006, 3,178, 3,644, 

 and 2,396 lbs. per acre, respectively, while those receiving winter irrigations 

 totaling 5 and 10 in., respectively, produced 2,512 and 3,-585 lbs. of potatoes as 

 ccompared with 2,709 lbs. for no winter irrigation. In a similar manner, plats 

 receiving no summer irrigation and 1, 2, and 3 irrigations during the summer 

 l)roduced 2,372, 2.265, 4,115, and 3.791 lbs., respectively. In a comparison of 

 level, ridge, and Greeley cultivation respective yields of 3,388, 3,172, and 1.967 

 lbs. per acre were obtained. Stable manure applied In 1916 resulted in a. yield 

 of 3,259 lbs. in 1918, as compared with 2,942 lbs. for the unmanured plats. 



[Report of field crops work in North Dakota] {North Dakota Sta. Rpt. 1917, 

 pp. 5, 6, 9, 10, 12-14, 16). — In the tests here reported, IMinnesota No. 13, 

 Rustlers White Dent, and Mercer corn produced the largest yield of silage. 

 Seed harvested in the glazed stage gave about as good a stand and yield as 

 ripe seed, while that harvested in the dough and milk stages produced a fair 

 stand but low yields. Manuring appeared to hasten maturity in corn, while 

 corn grown in rotation with clover is said to have been of better quality than 

 that grown in rotation with timothy. 



Where wheat has been grown continuously for 30 years the soil was found 

 to contain from one-fourth to one-third less nitrogen and one-fifth less phos- 

 phorus than virgin soil of the same type. For the last 8 years the wheat 

 yield was 28 per cent less than for the first 8 years of the period. Maniiring 

 brome grass is said to have increased the yield of hay 72 per cent, together 

 with a marked increase in the nitrogen and phosphorus content of the soil. 



Clover proved to be more profitable in the rotation than timothy or peas, 

 while alfalfa was also quite profitable. A rotation of corn, wheat, barley, 

 clover, and wheat produced the maximum return, the average annual value 

 of the crops produced from 1910 to 1916, inclusive, amounting to $24.49 per 

 acre, as compared with $12.06 for wheat grown continuously. 



One-ton applications of fresh and rotted manure resulted in average in- 

 creases in the value of the crops of $1.13 and $1.22, respectively. In view of the 

 loss from rotting and the extra labor involved the trial is held to indicate that 

 it is more profitable to haul manure directly to the field than to compost it. 

 130002°— 19 4 



