LIMING ONIONS 



By J. P. Jones' 



In the summer of 1926 many set onions were found to be turning 

 yellow at the tips, with the leaves dying hack, and growth stunted. In 

 several cases there was little growth beyond that which would naturally be 

 accounted for by the set itself. So prevalent were these conditions that 

 the County Agent of Hampshire County, Mr. Roland Payne, in coopera- 

 tion with the Miassachusetts Agricultural Experiment Station, made a 

 careful study of 114 onion fields on which sets were growing, located in 

 Hadley, North Hadley, Hatfield and Bradstreet. The fields were selected 

 at random, soil samples taken, and yield records obtained. In the labora- 

 tory, soil acidity determinations were made on eaclh of the samples. 



Many Onion Soils Too Acid For Best Growth. 



There are a number of methods for measuring soil acidity. In the 

 work reported here the Soil-Tex was used for rough estimations in the 

 field; the Wedge Comparator for the more exact laboratory measurements. 

 For both methods the uinit of measurement is called pH. (See figure 1). 

 The neutral point is pH-7, and is neither alkaline nor acid but of thf; 

 same reaction as pure water. Above pH-7 is alkaline and below it acid of 

 varying degrees. 



Practically all omion soils are acid and fall within the range indicated 

 in figure 1 — pH-4.0 to 7.0. The best onions generally grow in the slightly 

 acid soil, pH-6.0 to 7.0. Those grown on soils with a reaction of pH-.5.0 

 to 6.0 are only fair, while attempts to grow onions on a soil with reaction 

 below pH-5.0 result usually in failure. 



An interesting point illustrated by the data in Table 1 is that 58 

 fields, or about 50 per cent of those examined, were very acid^ — too acid 

 usually to produce a maximum crop. It is true that even on this very 

 acid soil, below pH 5.1, 13 fields gave a yield of 250 bags per acre or 

 more; but this small number compares unfavorably with the 45 fields 

 having a similar degree of acidity w'here the yields were poor. 



Table 1. — Influence of Soil Reaction on Yields of Onions. 



'. The writer wishes to thank ;Ur. Roland A. Payne, formerly County Agrent of Hamp- 

 shire-County, for assistance in collecting soil samples and yield records; and also Mr. 

 Orman E. Street, formerly of the Agronomy Department, for help in making pH de- 

 terminations. 



