ANNUAL REPORT, 1939 11 



be planted in the fall, the crop could get an earlier start. During the past two 

 seasons preliminary selection of onion plants was made for the purpose of obtain- 

 ing new types that will possess the characters of high yield and winter resistance, 

 and at the same time will be of the quality desired by the market. Some very 

 promising types have been obtained. Seed sets from these selected types, if 

 planted in the early part of September, will make considerable growth during 

 fall, resume growth early in the spring, and mature good-sized bulbs at the same 

 time as the commercial Ebenezer onions. The characters for "bolting" and winter 

 injury due to freezing and heaving of soil, however, must be bred out and practical 

 problems of fertilization must be solved before the fall planting of sets can be 

 adopted by the commercial growers. 



The Effect of Arsenious Oxide (AsjOg), Arsenic Oxide (As^Og), and Antimony 

 Oxide (SboOg) on Soil and Plant Growth. (Hrant M. Yegian and Walter S. 

 Eisenmenger.) The question of whether arsenic is cumulative in the soil and may 

 eventually become harmful to plant growth is important in areas where orchards 

 have been sprayed over long periods or where much arsenic has been applied to 

 lawns for parasites. Antimony was included in the study, not because of its 

 intensive use in agriculture but simply to learn whether an element with chemical 

 properties similar to arsenic acts in the same manner. 



Greenhouse experimental evidence on the effects of arsenious, arsenic, and 

 antimony oxides on Merrimac fine sandy loam and subsequent crop growth 

 warrants the following statements: antimony oxide applied to a series of pots 

 did not affect either plant growth or yields of barley and buckwheat, and the soil 

 was not injured even temporarily by applications up to 2000 p. p. m. The pH of 

 the soil at all concentrations was the same, and the nitrification in soil was not 

 depressed. 



Three successive pot tests were run for each of the arsenic treatments. The 

 pH of the soil dropped from 6.1 to 5.6 with the heavier application (2000 p. p.m.) 

 of arsenious and arsenic oxides. Arsenious oxide (2000 p. p.m.) and arsenic oxide 

 (600 p. p.m.) did not appear to retard nitrification of cottonseed meal in soil. 

 In the first crop test arsenic oxide, which is very soluble in water, showed a 

 higher toxicity than arsenious oxide, which is relatively insoluble in water. The 

 difference in toxicity of these two oxides was not so pronounced in the second 

 run, and there was no difference in the third run. Concentration of soluble arsenic 

 in the soil, therefore, seems to be the primary cause of arsenic toxicity. The 

 injurious effect of arsenic is primarily on the root system of plants. Plant species, 

 however, vary in susceptibility to arsenic toxicity; furthermore, in open-pol- 

 linated varieties there is a variation in the susceptibility of individual plants. 

 Continuous cropping is not so effective in reducing arsenic toxicity as is the in- 

 crease of organic matter of the soil. In soil, sorption of soluble arsenic takes 

 place in the presence of organic matter. Accordingly, in addition to other soil 

 factors, arsenic toxicity can be related to the organic matter in the soil, being high 

 in soil deficient in organic matter and low in soil well supplied with organic matter. 



Relationship of Natural Vegetation to Phy si co-Chemical Properties of Soils 

 of Massachusetts. (Walter S. Eisenmenger and Walter S. Colvin.) Natural 

 vegetation is often an index of the land's potentialities. In this study plant type 

 was correlated with soil type, water-holding capacity of soil, and pH of soil. 

 A total of 425 sites (uncultivated) was investigated and the following observa- 

 tions made. 



In correlating plant types with the water-holding capacity of the soil, plants 

 were divided into four groups: those most abundant on land with low water- 

 holding capacity (40 to 50 percent), such as pitch pine, broom sedge, and lespedeza ; 



