Agricultural Research in New Hampshire 21 



Due to a very dry season in the Colebrook area in 1944, potato \ields 

 were verv low and the results did not confirm those that had been ob- 

 tained in 1942 and 1943, when increases of from 16 to 59 bushels per acre 

 were recorded for varying amounts of gypsum. 



The lack of response in 1944 is attributed to low rainfall and to the 

 fact that water rather than plant food was the limiting factor. 



These same weather conditions hampered other phases of the experi- 

 ment, but the results of fertilizer placement studies follow those of pre- 

 vious vears, regardless of the low yields. There is an advantage for band- 

 ing over any other method of placement, whereas, according to these 

 data, there is no advantage in banding one substance and broadcasting 

 the others as compared with broadcasting all ingredients. 



Because of the extreme drouth we are not presenting the 1944 yields 

 of the fertilizer ratio test. The plots varied too much for any signifi- 

 cance, and the positional difference of the various plots had a greater ef- 

 fect than any variation in treatment. 



Tuber samples were taken from the different fertilizer treatments 

 and also of the different varieties in the variety test; then the cooking 

 qualitv was determined by the specific gravity method. Salt solutions 

 of different specific gravity were used to float each portion of the sample 

 and a weighted average of each sample recorded. It has been found that 

 potatoes having a specific gravity of 1.055 to 1.070 are certain to be 

 soggv, while from 1.075 to 1.080 they could be classed as fair. When 

 the specific gravity is 1.085 or 1.090 the tubers are mealy enough to be 

 classed good, while those above 1.095 are very mealy and are classed ex- 

 cellent. 



Of the new varieties, Potomac and Mohawk were the onh" varieties 

 that compare favorably with Green Mountain and Russet. The quality 

 rating was reduced on plots receiving a high potash content in the fer- 

 tilizer and was raised when the phosphorus was increased. This checks 

 with all previous data. Variations due to fertilizer are slight. Plots 

 treated with calcium sulphate as an amendment have a tendency to be of 

 higher quality. 



A topsoil, low in calcium, low in organic matter, and, because of 

 the latter condition, low in readily mineralized sulphur, was placed in 

 boxes built into a greenhouse bench. Each box contained 65 pounds of 

 moist soil and was regarded as equivalent to l/7260th of an acre with two 

 seed pieces set approximately one foot apart. The seed pieces were cut 

 from the bud end of Green Mountain tubers (at least lYz ounces per 

 piece) which had previously been green sprouted to permit elimination 

 of weak sprouting buds, thereby minimizing the danger of having leaf 

 roll plants present in the experimental population. 



The fertilizer treatments were made equivalent in N, P and K to 

 an application of one ton per acre of 6-12-12. All salts, except the gyp- 

 sum and limestone, were C. P. chemicals. The various mixtures were ap- 

 plied in bands on either side of the seed pieces and approximately three 

 inches below the surface of the soil. 



The results indicated that the influence of both calcium and sulphur 

 in the nutrition of the potato is reflected primarily in an increase in both 



