32 MASS. EXPERIMENT STATION BULLETIN 195. 



been gone over and the results tabulated. Two of the plots were Havana 

 and the third Cuban shade-grown. There has been a general similarity 

 shown by the results on all of the plots. 



In addition to the special treatments indicated below, it should be 

 remembered that all the plots received an application of a 5-4-5 mixture, 

 equivalent to an application of 3,000 pounds of commercial mixed goods 

 of the same analysis per acre, except, of course, the no-potash plots. 

 These received no potash in any form, except such as was in the manure 

 or the cottonseed. 



There was a marked increase in yield both in 1917 and 1918 on the plots 

 which had received an application of organic matter in the form of peat 

 at the rate of 2 tons to the acre (on a 12 per cent moisture basis), and also 

 a slightly heavier yield with better quality on the manure plots than on 

 the peat, the manure being applied at the rate of 10 tons to the acre. 

 There was a still more marked increase in yield on the plots which had 

 received organic matter, either as peat or manure, and acid phosphate 

 at the rate of 300 to 600 pounds per acre. Where acid phosphate alone 

 was used in conjunction with the regular fertilization without the addition 

 of organic matter in some form the results even on the same plot were 

 sometimes rather conflicting. It can only be stated that no uniformity 

 of results was obtained. In some cases a marked benefit was noted as a 

 result of the treatment; in others, on the same field, the results were 

 apparently negative. 



With respect to the lack of potash it was noticeable that there was no 

 lack of this material indicated on any of the plots in 1917 and 1918. No 

 differences were observed, so far as this material was concerned, between 

 the plots which received applications of 350 pounds of high-grade sulfate 

 of potash and those wliich received none at all. It should be stated, 

 however, that the experimental plots were all located on land which had 

 in the years prior to 1914 received liberal applications of potash, and it is 

 quite probable that the supply of available potash in the soil was in no 

 case exhausted. During the growing season of 1919 there were indications 

 that on one of the fields there might be developing a lack of potash. The 

 symptoms were not characteristic enough to warrant a positive statement 

 on this point. 



There is no evidence that our soils in general are suffering from a lack 

 of potash, although a few local areas where this was the case have been 

 brought to our attention during the past year. These cases were all on 

 light soils and on soils which had not in the past received any heavy appli- 

 cations of potash in the fertilizer used. It would appear that new soils 

 which have been used for a comparatively short period only before the 

 shortage of potash are more liable to be suffering from a lack of potash 

 than are some of the old fields which have for years received a xery liberal 

 application of this material. On these fields it is probable that there is an 

 accumulation of potash in the soil sufficient to have carried the crop over 

 the period of the shortage. 



