LEGUMES AND GRASSES 



13 



second and third year. These 

 workers concluded that sod crops 

 were of no value in short rotations. 



In 1951, Osenbrug and Mathews 

 (65) discussed dryland crop pro- 

 duction at the Belle Fourche Field 

 Station at Newell for the previous 

 40 years. Annual precipitation 

 averaged 16.1 inches. The soil was 

 initially low in organic matter and 

 nitrogen and subject to wind erosion. 



Their data indicate that 40-year 

 average yields (table 7) of both 

 wheat and oats were higher on 

 unman ured fallow than immediately 

 after green-manure fallow. Yields 

 on green-manure fallow were 

 generally higher than on ordinary 

 fallow in good seasons. In un- 

 favorable years, the green-manure 

 crop depleted soil moisture so that 

 the succeeding crop was more 

 subject to drought damage. 



Legumes Versus Inorganic Nitrogen 

 Sources 



In 1957, Worzella and coworkers 

 (83) published a progress report 

 on research in crops and soil on 

 the Agronomy Farm at Brookings, 

 S. Dak. They had started new 



rotations in 1954 to compare leg- 

 umes as a source of nitrogen with 

 nitrogen fertilizer. They tabulated 

 data on yields of corn in 1955 and 

 1956 and oats in 1956 (table 8). 



In 1955, corn yields were limited 

 by July drought. Mature sweet- 

 clover plowed under the previous 

 year produced the lowest corn 

 yields (table 8). Twenty pounds 

 of nitrogen on the nonlegume rota- 

 tion produced the highest corn 

 yield. In 1956, mature sweetclover 

 and alfalfa plowed under the pre- 

 vious year produced the highest 

 corn yields. The greatest oat 

 yields were produced with 20 

 pounds of nitrogen per acre. 



In 1957, the Agronomy and 

 Plant Pathology Departments of 

 the South Dakota Agricultural Ex- 

 periment Station initiated experi- 

 mental work at two new research 

 farms (72, 73). The Southeast 

 Research Farm was located near 

 Menno in Hutchinson County. 

 The soil is loam and clay loam in 

 association with alkali claypans. 

 Annual precipitation averaged 23.8 

 inches. The Northeast Research 



Table 8. — Yields of corn and oats in various rotations and with legumes as 

 source of nitrogen and with nitrogenous fertilizer, Brookings, S. Dak., 

 1955-56 l 





Nitrogen 



added 

 per acre 2 



Yield 



, per acre 



Gi- 



Rotation 



Corn 



Oats, 





1955 



1956 



1956 



Corn, oats, flax, wheat 



Pounds 















30 



20 



40 



60 







Bushels 

 31.7 

 22.9 

 15.9 

 33.2 

 39.8 

 35.8 

 32.9 



Bushels 

 62.5 

 61.7 

 67.4 

 62.6 

 63.2 

 62.3 

 60.8 

 67.0 



Bushels 

 33. 6 



Corn, oats, flax, sweetclover 



27.6 



Corn, oats, flax, mature sweetclover 



Corn, oats, flax, sweetclover 



28.5 

 41.2 



Corn, oats, flax, wheat 



45.3 



Do 



38. 3 



Do 



30.8 



Corn, flax, alfalfa, alfalfa _ 









i Data from Worzella and coworkers (83). 

 * Annual applications for the grain crops. 



