28 MASS. EXPERIMENT STATION BULLETIN 315 



The Copper, Iron, Manganese, and Iodine Content of Fruits and Vegetables 

 Used as Human Foods. (E. B. Holland, C. P. Jones, and W. S. Ritchie.) One 

 hundred and twenty-five samples of fruit and vegetables, suitable for human 

 consumption, have been collected and prepared for analysis. The actual work 

 of analyzing the samples has been started and will be continued through the 

 coming year. 



Absorption by Food Plants of Chemical Elements of Importance in Human 

 Physiology and Nutrition. (A. B. Beaumont and E. B. Holland.) Under this 

 cooperative project, Agronomy raises food crops under special fertilization to 

 supply samples for the determination of copper, iron, manganese, and iodine in 

 nutritional studies. Samples of spinach and turnips, fertilized with varying 

 amounts of potassium iodide, have been taken and prepared for analysis. These 

 samples will be analyzed during the coming year as part of the preceding project. 



Cooperative Analytical Service. (The Department.) Additional cooperative 

 investigations embrace a variety of substances and consume a great deal of 

 laboratory time. Milk and eggs were analyzed for certain ash constituents. 

 Additional samples have been taken to study "dark centers" in turnips. Iron 

 and manganese were determined in greenhouse sands, for flower raising, in co- 

 operation with the Waltham Field Station. 



Testing Analytical Methods. (The Department.) The accepted methods for 

 the determination of small amounts of iron, copper, iodine, and manganese in 

 organic materials have been studied and adapted to the needs of the above 

 investigations. 



An electrically heated dryer with a forced circulation of air has been con- 

 structed during the past season for the preparation of fruit and vegetable samples 

 at a moderate heat and has proved very efficient and time-saving. 



Nitrogen Fixation in the Presence of or as a Result of the Growth of Legumes 

 versus Non-legumes Under Certain Defined Agronomic Conditions. (F. W. 



Morse.) Alfalfa as the legume and barley as the non-legume were sown August 

 5, 1933, with the intention of continuing the alfalfa for at least two years. The 

 alfalfa was not cut but was allowed to develop as much top-growth as possible 

 for winter protection. The barley was also left to serve as winter cover for the 

 soil and as a store of organic matter for the soil bacteria. 



In the spring of 1934, the alfalfa was observed to have been nearly all winter- 

 killed except a narrow strip along the western border of the plots where snow re- 

 mained longest. The whole field was plowed and prepared for Hungarian millet 

 which was planted on all plots. Nitrogen was withheld from Plots 5, 8, and 10. 

 The results permit a comparison of the effects of leguminous residues with those 

 of non-leguminous residues on the growth of a non-legume, Hungarian millet, 

 together with the effects of the residual nitrogen from 1933 with that of the 

 continuous withholding of nitrogen from Plots 6, 7, and 9. Hungarian millet was 

 seeded on June 9 and cut on August 6, 7, 8, and 9 when in full bloom. During this 

 period there was 6.88 inches of rainfall, which is one of the smallest in our records. 

 The eastern half of the field is more moist than the western half. The millet 

 following barley on the eastern half was superior to that following alfalfa, but on 

 the drier western half the millet on alfalfa residue was superior. These differences 

 observed throughout the growing period are definitely shown in the table of pro- 

 duction of dry matter. 



