10 University of New Hampshire [Sta. Bull. 324 



was doubled (4-16-7), indicate that this variety is particularly res])onsive 

 to phos])horic acid and much more sensitive to variations in this plant nu- 

 trient than to potash. This may be true of other varieties. 



Lane Farm Trials 



Results for fertilizer variations on tlu' Lane Farm are presented in 

 Table v. 



TABLE V. Six-year average yields of Lane farm potatoes 

 with varied fertilizers, 1933-38. 



Tn comparing these data with those in Table I it will be noted that 

 total yields are much lower and that variations due to the omission or in- 

 crease of the elements are considerably smaller. The only statistically 

 significant difference in Table \' is the decrease of 55 bushels in yield of 

 the 4-8-0 series. It will be further noted that the decreases for omission 

 of elements are in the same relative order as in Table I, and further, that 

 extra nitrogen (8-8-7 j gave less response than either of the other two 

 series in which elements were increased. 



In spite of lack of statistical significance in the data, there has been 

 a consistency in results over the years which sliould lend some weight to 

 their value. Probably no one who had seen the ])lots during their growth 

 would doubt that the plots that did not receive phosphoric acid would 

 yield as well as those receiving normal fertilization. Likewise, it was ap- 

 parent each }'ear that the additional phos])horic acid and potash greatly 

 stimulated the growth of vines and foliage, and this additional leaf surface 

 is generally translated into tubers later on. Over a perif)d of si.x years, 

 therefore, it seems safe to conclude that the l.ane farm data supi)ort those 

 of the Jackson farm in pointing to the need for slightly more phosphoric 

 acid and potash thin is found in a 1-2-2 or similar ratio. 



Lime in Potato Rotations 



Linir was used in both the.se experiments at \ar\ing rates to deter- 

 mine if lime could be used in a potato rotation. ])o\v much could safely 

 be aj)plied, and what effect the lime would have on potato yields as well 

 as on the hay crops that follow. 



In the first six-year period on ihc Jackson farm, lime was applied at 

 the rates of two and four tons per acre on separate series. This was not 

 applied directly for potatoes, but after the potatoes were grown and prior 

 to seeding the land lo the hav cr(»p. Hence, there are but three vears' data 

 on lime effects on potato yields re])orted here. Groiuid limestone was used 

 in these tests. 



