6 MISCELLANEOUS PUBLICATION 952, U.S. DEPT. OF AGRICULTURE 



land was occupied. Where a stand 

 was established, he recommended 

 that it be retained for several years 

 rather than being plowed up with 

 the hope of benefiting succeeding 

 grain crops. There was no meas- 

 ured cumulative effect from green 

 manure, and a legume was of no 

 more value than a nonlegume. 



In 1931, Chilcott (10) reported 

 on tillage and rotation experiments 

 at Edgeley. The soil at Edgeley is 

 shallow — about 2 feet over shale. 

 This soil has a very limited mois- 

 ture-storage capacity. Annual pre- 

 cipitation averaged 17.4 inches. 

 Spring wheat yields after green - 

 manure fallow were 2 to 3 bushels 

 per acre greater than that after 

 ordinary fallow (table 1). Oat 

 yields were lower with green-ma- 

 nure fallow than with ordinary 

 fallow. 



In 1936, Sarvis and Thysell (71) 

 reported on crop-rotation and tillage 

 experiments at the Northern Great 

 Plains Field Station at Mandan. 

 Annual precipitation averaged 15.2 

 inches. Green manuring was a 

 more expensive seedbed prepara- 

 tion than summer-fallowing, and 

 the results with spring wheat to 

 1934 did not justify this practice 

 (table 1). Alfalfa averaged nearly 

 a ton of hay per acre per year, and 

 bromegrass yielded about half this 

 amount (71). 



In 1948, Carpenter (8) reported 

 the effect of organic amendments 

 on crop yields at Mandan. Green- 

 manure crops increased yields in 

 some years, but the increase did not 

 justify the extra expense. Green- 

 manure crops had been of no benefit 

 to the soil. 



In 1953, Conlon and coworkers 

 (18) reported on rotation and tillage 

 investigations at Dickinson. They 

 found that yields of oats after rye 

 green-manure fallow averaged about 

 4 bushels per acre more than after 

 ordinary fallow (table 1). How- 



ever, results to 1951 did not justify 

 the practice of green manuring 

 because of extra costs. Sod crops 

 were unsuited to short rotations 

 because they left the soil in a dry 

 condition. This was reflected in 

 reduced yields of the following grain 

 crops. 



In 1955, Haas (24) showed that 

 soil fertility had become limiting 

 for crop production on Cheyenne 

 fine sandy loam at Mandan. He 

 gave relative yields of wheat and 

 corn for two periods — 1915-18 and 

 1947-53 (table 2). 



Annual precipitation averaged 

 15.7 inches for the first period and 

 16.7 inches for the last period. 

 During the later period, highest 

 yields were from rotations contain- 

 ing alfalfa or receiving manure. 

 Sweetclover in the rotation with 

 wheat apparently benefited wheat 

 and corn yields. Grass in the rota- 

 tion did not benefit wheat, but it did 

 improve corn yields. Continuous 

 corn produced the most grain during 

 the first period but least during the 

 last period. 



In 1958, Haas and Boatwright 2 

 cautioned that spring wheat after 

 grass or legumes at Mandan may 

 suffer from severe moisture defi- 

 ciency, which counteracts any bene- 

 ficial effect from the previous sod 

 crop. Corn was considered to be a 

 better crop than wheat after sod. 



In a later report, Haas and 

 Boatwright (26) snowed that wheat 

 yields after wheat, corn, and green- 

 manure fallow were all increased to 

 the same yield level at Mandan by 

 adding 80 pounds of N and 40 

 pounds of P 2 5 . They conducted 

 this experiment on Cheyenne fine 

 sandy loam from 1955 to 1957. 

 Second-year wheat yields were 



2 Haas, H. J., and Boatwright, G. O. 



GRASS, LEGUME, AND FERTILIZERS AFFECT 



spring wheat yields. Northern Great 

 Plains Field Sta., Mandan, N. Dak. 

 [Unpublished Res. Rpt.] 1958. 



