Agricultural Research in New Hampshire 27 



was obtained by an increase in this element. As the 4-16-4 fertilizer cost 

 only $0.30 per hundred pounds more than the 4-8-4 formula, there was 

 a net gain each year from the higher proportion of phosphorus. 



The averages of all plots in regard to amounts of fertilizer applica- 

 tions for the two years indicate a gain of 0.8 ton per acre by the use of 

 1,000 pounds of fertilizer as compared to 500 pounds. The increase in 

 1940 was practically a ton per acre and in 1941 a little less than three- 

 quarters of a ton, again emphasizing the influence of rainfall on results. 



The use of high-phosphorus formulae and the application of 1,000 

 pounds of fertilizer per acre, without manure, have been justified in both 

 seasons. 



As good results have been secured with manure and superphosphate 

 as with complete fertilizers. In 1940 the yields with manure and super- 

 phosphate were better than with fertilizers alone. There is evidence from 

 the 1940 work that extra fertilizer in the planter in addition to manure 

 and superphosphate broadcast is a factor causing increased yields. This 

 result was not duplicated in 1941. (F. S. Prince, P. T. Blood) 



Rotation Fertility and Cultural 

 Experiments with Potatoes 



This project is located in Colebrook, New Hampshire. This is the 

 end of the second year's work. Different fertilizer formulae, plant food 

 levels, and methods of application of fertilizers to potatoes are being 

 tested, and in 1941 several different nitrogen carriers were used in one 

 series of plots. Three rotations are also in progress in this test. In one, 

 potatoes are grown continuously, in another two-year rotation different 

 cover crops are being tested, and the third is a four-year rotation with 

 the usual hay crops being grown. Organic matter and soil structure 

 studies will be made on samples taken in the beginning and at the end of 

 a five-year period. 



Variations of potash and phosphoric acid with a uniform level of 

 nitrogen indicate for the two years that varying the potash causes much 

 more variation in yields than varying the phosphoric acid. Also, a half 

 ton of 8-16-16 fertilizer gave as good a yield of potatoes as an equivalent 

 amount, 1,600 pounds, of 5-10-10. 



The effects of methods of fertilizer application were checked. Yields 

 in this respect did not vary as widely in 1941 as in 1940. Yet their rela- 

 tive positions were the same. The data- point to the necessity of banding 

 the fertilizer for highest yields. 



Results from the use of different sources of nitrogen carriers, initiated 

 in 1941, indicated that the less soluble or less available the nitrogenous 

 products used, the better. The yields resulting from this factor, using 

 equal amounts of plant food but in different forms, varied by as much as 

 50 bushels. (F. S. Prince, P. T. Blood, C. L. W. Swanson, G. P. 

 Percival) 



Potato Seed Certification 



The potato seed certification service was started in New Hampshire 

 in 1921. Both the field and bin inspections were under the direction of 

 the late Dr. O. R. Butler until his death in 1940. In March. 1942. the 



