ONIONS IN THE CONNECTICUT VALLEY 7 



onions to 1 and 2 tons of lime. In the early stage of the experiment there was a 

 definite response to the 3 or more tons of lime, but in the latter stages the advan- 

 tages of the higher amounts became less. 



To study effect of the different amounts of lime on the reaction of the soil, the 

 pH values of soil samples drawn in 1925, 1928, and 1932 were determined. The 

 figures indicated that it was difficult to raise the reaction of this soil above pH 6.4 

 by liming. Such a soil is said to be well buffered, and the buffer property is due 

 to the presence of considerable fine mineral and organic matter. A soil containing 

 more medium to coarse sand particles than this one would be expected to behave 

 differently; the changes in pH values being greater. 



The conclusion drawn from these experiments in the liming of a soil for onions 

 is that on a soil of this kind and with approximately the same initial reaction 

 (pH 5.3) lime is necessary, but little if any advantage may be expected from 

 applications of lime above 3 tons. The optimum soil reaction range appears to 

 be about pH 6.0 — 6.5. Once this range is attained, it can be maintained by an 

 application of 1 to 2 tons of lime per acre once every 2 or 3 years. Less lime will 

 be needed for the light sandy soils than for the heavier loams, but it must be 

 applied more frequently. Ordinarily, it is better to apply the lime in the fall 

 preceding the year in which the crop is to be grown rather than in the spring 

 immediately before seeding. Tobacco requires a soil of lower reaction than is 

 suitable for onions, and will not do well on soils limed correctly for onions. Similar 

 deductions regarding the needs of onions for lime were made from a study of 114. 

 Connecticut Valley farms in 1927 L 



Fertilizer Ratio Experiment 



In this experiment the 4-8-4 grade 2 was chosen as the standard check and was 

 supplied at the rate of 2500 pounds per acre. In this formula as well as the others 

 in this experiment, one-half the nitrogen was from an organic source, animal 

 tankage, and the other half was equally divided between nitrate and ammonium 

 forms; the phosphorus was supplied by ammo-phos and superphosphate; and 

 muriate of potash supplied the potassium. The fertilizer was applied broadcast 

 and harrowed in before seeding or planting. Fertilizer grades used were: 4-8-4, 

 6-8-4, 4-12-4, 2-12-8, 4-12-8, 6-12-8, 4-8-8, 6-8-8. 



From the first year of the experiment the 4-12-8 grade yielded the most onions, 

 and the superiority of this grade continued throughout the experiment. Differences 

 of about 25 per cent in yield of seed onions, and about 10 per cent in set onions, 

 were necessary in order to be significant. The higher amounts of phosphorus 

 and potassium produced significant increases only when used together in the same 

 mixture. On account of the superiority shown by the higher amount of phos- 

 phorus, a still higher amount of that element was tried, but with no consistent 

 advantage. 



The response obtained from phosphorus applied to this soil is explained in 

 part by the results of chemical analysis. Available phosphorus was determined 

 by the Truog method 3 in samples drawn before the experiment was started, and 

 in the spring of 1932. In the original soil there were 60 pounds of available phos- 



'Jones, J. P. Liming onions. Mass. Agr. Exp. Sta. Bui. 237 (1927). 



2 These figures refer to perentages of nitrogen expressed as ammonia (NH 3 ), phosphoric acid 

 (PiOs), and potash (KiO) respectively. 



'Truog, Emil. The determination of readily available phosphorus in soils. Jour. Amer. Soc. 

 Agron. 23:788-799 (1931). 



