12 



CONSERVATION RESEARCH REPORT 5, U.S. DEPT. OF AGRICULTURE 



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-1000 +2000 +4000 +6000 



MEAN DIFFERENCE IN YIELD (LB. /ACRE) 



Figure 6. — Mean soil moisture content was lower on the nitrogen-fertilized plots than on the F2 plots when large differences 



in yields occurred. 



table 17). In 1956, the protein content averaged 

 15.3, 14.0, 13.4, 11.3, 12.1, and 14.3 percent for 

 progressively increasing moisture treatments. In- 

 dividual fertilizer treatments were not analyzed 

 in 1956. 



In 1957, protein content on the Mi moisture 

 level averaged 11.65 percent as compared with 

 8.30 and 8.18 percent on the M 3 and M 5 levels, 

 respectively. The 2-year average yields (1956 and 

 1957) on these treatments were 2,159, 5,548, and 

 5,894 lb /acre, respectively. The weighted mean 

 protein content for 1957 and 1958 was about 11 

 percent with average yields of about 3,000 lb. 

 (weighted mean=sum of yield x protein content 

 for each year /total 2-year yield). With larger 

 yields on higher moisture levels, protein content 

 was lower. 



With average yields of about 5,000 lb. /acre, 

 protein content averaged 6.3 percent on the 

 0-nitrogen plots. With 240 lb. /acre of nitrogen 

 applied in 1956 and 1958, protein content averaged 

 only 8.5 percent when yields averaged 6,400 lb./ 



acre. Thus, protein content was maintained to a 

 certain extent when nitrogen applications exceeded 

 that needed for yield. 



Other Crop Characteristics 



Plant Height 



The height of the sorghum increased with the 

 first two increments of applied nitrogen id 1958 

 but decreased slightly at the highest rate. Very 

 little difference between nitrogen rates occurred 

 in 1957 and 1959 (table 6). Low soil moisture 

 during the late boot stage reduced plant height. 

 The shortest plants were on the Mi moisture 

 level. 



Heading Dates 



Date of heading was delayed on plots receiving 

 no nitrogen (appendix table 18). Heading was 

 earliest on the low moisture levels. 



