SOIL NITROGEN 5 



very severe thunder showers occurred. The crop then showed the unequal 

 effects which weather may sometimes have in field experiments. Millet on 

 the nonlegume subplots without nitrogen remained erect and continued its 

 growth unhindered. On the plots with nitrogen the millet was completely 

 flattened and never regained its erect form. The legume subplots without 

 nitrogen were partially flattened and recovered somewhat better than those 

 with nitrogen. Consequently the millet without nitrogen was more nearly 

 equal to the crop with it than would probably have been the case under normal 

 weather conditions. 



1931. Oats and field peas were sown on the legume and oats alone on the 

 nonlegume subplots. An early crop was selected to ascertain how it responded 

 to residual nitrogen and no nitrogen. Oats appeared to be uniform in height 

 throughout the field. The field peas made the growth on the legume subplots 

 appear to be denser than on the areas with oats alone. The crops were har- 

 vested before seeds were filled in both oats and peas. After these crops were 

 removed a growth of barnyard grass covered the field and was most abundant 

 on the nonlegume areas. "White clover also showed on these areas and the 

 field was plowed to prevent its further development. 



1932. Soybeans were sown on the legume and Hungarian millet on the 

 nonlegume subplots, and nitrogen was applied to Plots 5, 8, and 10. Both 

 crops showed the effect of nitrogen by larger plants and darker green foliage. 

 Weeds were prominent on the nitrogen plots but were found to constitute an 

 insignificant part of the crop. The crops were cut when the millet was in 

 bloom and before the soybeans formed pods. A cover crop of mixed barley, 

 buckwheat, and oats followed the removal of the soybeans and millet. This 

 cover crop was killed by frost but served to protect the surface from winds. 



1933. It was planned to use alfalfa as a perennial legume and accompany 

 it with annual nonlegumes. Barley was selected to accompany the alfalfa this 

 year. Since alfalfa in its earliest stages responds to nitrogen fertilizer, Plots 

 5, 8, and 10 received their usual allotment. Seeding was deferred until July 

 and the field was repeatedly harrowed to destroy weeds. Both alfalfa and 

 barley developed normally. It was planned to leave the alfalfa uncut for 

 better winter protection; consequently the barley was left unharvested. On 

 October 10 the barley was fully headed with kernels partly filled. The nitro- 

 gen plots showed a height of 36 to 40 inches, while without nitrogen the height 

 was 28 to 38 inches. Alfalfa with nitrogen was from 8 to 11 inches tall, and 

 without nitrogen, 5 to 10 inches. A heavy frost on October 25 prostrated the 

 barley on the nitrogen plots, but the plants without nitrogen remained erect 

 until the next severe frost. 



1934. The alfalfa was nearly all winterkilled; therefore, the whole field 

 was plowed and a liberal amount of organic matter was turned under, espe- 

 cially on the nonlegume subplots. Hungarian millet was sown on all subplots 

 on June 9. Nitrogen was omitted. The appearance of the field was quite 

 uniform as the crop advanced; but when fully headed, Plot 10 was definitely 

 taller than any other plot. The west tier of nonlegume subplots bore shorter 

 plants than the legume subplots; but the east tier of nonlegume subplots bore 

 taller plants than the adjacent legume tier. 



1935. Nitrogen was applied to Plots 5, 8, and 10. Oats and field peas 

 were sown on the legume subplots, while oats alone were used as the nonlegume 

 crop. These crops were chosen for comparison with like crops grown in 1931 

 without applied nitrogen. Oats on the nonlegume subplots showed a marked 

 effect from nitrogen fertilizers. Oats and peas on the legume subplots were a 

 little superior on the nitrogen plots; but on those without nitrogen the oat 

 plants amid the peas were stouter and darker in color than the oats alone, and 

 much like the oats with nitrogen fertilizer. The crops were harvested as soon 

 as pods formed on the peas and the oats were fully headed but not filled. 



The succession of crops and application and omission of nitrogen are shown 

 in Tables 2 and 3. Yields of dry matter and nitrogen have been averaged for 

 the duplicate subplots on each plot, and are expressed in pounds per acre, 

 The subplots are grouped in their respective legume and nonlegume series, 

 together with the corresponding crops. 



