ONIONS IN THE CONNECTICUT VALLEY 9 



vegetative growth by about July 1, and from then on to maturity little nitrogen 

 should be needed for the "bottoming out" growth, which consists largely of stor- 

 ing carbohydrates. Second, it was noted that benefit was derived from the extra 

 materials by the seed onions, but there was considerable variation in results. On 

 the whole the sodium nitrate was superior to the fish meal, but there was one 

 year (1927) in which the fish meal was superior. 



These results appear to be correlated with the distribution of the rainfall 

 in the growing seasons concerned. In August of 1927 the rainfall was 5.01 inches, 

 against a normal of 4.24 inches. Possibly this excess of rainfall was sufficient to 

 throw an advantage to the more slowly available organic nitrogen. But the 

 summer of 1928 was excessively wet and cool, the rainfall for the three summer 

 months being almost twice the normal, and the organic material was much in- 

 ferior to the inorganic carrier. Likewise, in 1929, a year as dry in contrast as 

 1928 was wet, the organic material was inferior. In both years nitrification was 

 probably inhibited to such a degree that the full effect of the organic material 

 was not obtained, and it was, therefore, inferior to the sodium nitrate although 

 some of the latter may have been lost through leaching. 



By comparing these results with those from the 6-8-4 used in the fertilizer ratio 

 experiment some advantage seemed to lie with addition of part of the nitrogen 

 as side dressing. The experiment as a whole appears to justify the conclusion 

 that side-dressing with a nitrogen fertilizer may be beneficial to seed onions but 

 is not likely to help set onions. A nitrate is preferable to an organic material, and 

 probably will give better results than any other form of nitrogen. 



The interrelationship between the effect of different forms of nitrogen in 

 fertilizers and the prevailing weather is probably delicately balanced, so that a 

 slight shift of weather in one direction or another may radically affect results. 



Single Strength versus Double Strength Fertilizers 



When these experiments were started, concentrated or high-analysis, particu- 

 larly double-strength, fertilizers were becoming important commercially, and 

 questions as to their value in comparison with the ordinary mixtures were more 

 or less common. It was decided, therefore, to include a double-strength mixture 

 in the list of those tried. An 8-16-8 was mixed from urea, ammo-phos, and muriate 

 of potash, and this was compared with the standard 4-8-4. The results from the 

 two materials were almost identical. In this experiment, also, striking benefits 

 from lime were noted. 



Muriate versus Sulfate of Potash 



An old question in connection with fertilizers is that of the carrier of potash. 

 Shall it be the cheap muriate or the more expensive sulfate? On account of the 

 peculiar importance of sulfur in the formation of certain volatile oils found in 

 onions, it was decided to make a comparison between the muriate and sulfate 

 forms of potash as onion fertilizers. No significant differences were found in the 

 yields from the two sources of potash. As in other experiments alreadv noted, 

 marked beneficial effects of lime were obtained. 



