BUREAU OF PLANT INDUSTRY. 273 



moisture is a limiting factor in the successful development of the 

 crop. 



Soil-fertility studies. — Some valuable data have been obtained 

 showing the response of pecan trees grown on various soil types to 

 fertilizer treatments and cultural conditions. These investigations 

 comprise the study of soil conditions and fertilizer requirements of 

 pecans and were begun in 1918. The work is conducted on an or- 

 chard basis in the pecan belts of Florida, Georgia, and Alabama, 

 and large areas are under experimentation. Experiments are located 

 on the Greenville sandy loam, Orangeburg sandy loam, Norfolk 

 fine sandy loam, Norfolk sandy loam, Norfolk fine sand, and 

 Bladen fine sandy loam. A laboratory investigation of the nuts 

 produced on different soil types and under varying fertilizer and 

 cultural treatments has been made in connection with this work. 

 The protein, fat, and sugar content, as well as the yield, size, 

 and filling quality, of the nut were found to be influenced by 

 fertilizers and soil conditions. Larger and better filled nuts were 

 produced by complete fertilizer mixtures high in nitrogen. Potash 

 increased the oil or fat content and nitrogen the protein content of 

 the kernel. A study of the nature and chemical constituents has 

 been made of pecan oil, which was found to contain oleic, linolic, 

 palmitic, and stearic acids and a small amount of phytosterol. The 

 use of fertilizers and the growing of cover crops for green manuring 

 in connection with pecan growing are increasing, and information 

 concerning these factors is much needed. Some very good informa- 

 tion for the guidance of growers has been obtained. 



Nut storage. — The nut-storage investigations, which have been m 

 progress about three years and include storage experiments on several 

 different varieties of each of the commonW grown cultivated varieties 

 of nuts of the United States, are about completed. In this work it 

 has been shown that English walnuts can be stored for about three 

 years at 32° F. and will be in good condition at the end of that time. 

 The pecans at 32° F. were in fairly good condition at the end of 2^ 

 years, while even the best of the almonds had deteriorated somewhat 

 nt the end of that time. Filberts can be stored for two years and per- 

 haps longer at 32° F. At 40° F. the nuts deteriorate more rapidly 

 than at 32° and hardly last more than 12 or 15 months in common 

 warehouse storage. These experiments are about completed and the 

 results will be published soon. 



VEGETABLES. 



POTATOES. 



Improvement of seed stochs. — In connection with studies of the 

 seed-potato suppty investigations are being continued on the pro- 

 ductivity of mature and immature seed, the effect of storage tem- 

 peratures on the productivity of seed, the effect of the source of 

 seed supply as well as that of the size of the seed piece, together with 

 a test of germinated and ungerminated seed stock to determine the 

 best practices for growers to follow. In addition to these the line 

 of investigation of so-called " running out " of varieties is being 

 continued as well as the effect of the continuous use of seed potatoes 

 grown under irrigation. The investigational work in the field in 



