27 



following is ii suiiiniaiy oC tlio rosults obtJiiiied with fertilizers on po- 

 tatoes for tlie entire period that this work has been carried on by the 

 station. Tiie tests have been made on several different classes of soil 

 and in two different localities. As indicated in the bulletin, these resnlts 

 agree substantially with those reported for potatoes in a bulletin of 

 this Department on the Itesults of Field l^^xperiments with Various 

 Fertilizers, imblished in 1883. 



(1) Sulphate of potash and muriate of potash have in sonic instances increased the 

 yield, hut in no case sufficiently to make tlieir use profitable. 



(2) Nitr.ato of soda and sulphate of auunonia have in a few cases given a sliglit in- 

 crease in yield, but not to a proiitable degree. 



In seasons when blight has been the most severe these substances, especially the 

 former, have apparently exerted an injurious effect. 



(3) Superphosphate (dissolved bone-black), acid phosphate, and Thomas slag have 

 iu nearly all cases increased the yield. Thomas slag is the cheapest form in which 

 phosphoric acid can be obtained, and tlie trials indicate that its use on potatoes is 

 likely to be attended with greater profit than that of either of the other substances 

 named. 



(4) A mixture of sulphate of potash, superphosphate, and nitrate of soda has usually 

 given better results than superphosphate alone, but not always. 



(5) Barn-yard manure has increased the yield, but not always the total market- 

 able product, because of the usual prevalence of scab where this fertilizer is used. 



(fi) In no case has the potato croj) been benefited, to a profitable degree, by the ap- 

 plication of fertilizers of any kind on soil that was already in a high state of fertility. 



(7) On soil that had been worn by previous cropping, phosphatic fertilizers, the 

 so-called complete chemical fertilizer^-i, and barn-yard Jnanure have in nearly all cases 

 given profitable returns. 



(8) The rational conclusion is that since the potato requires a soil that is in a high 

 state of fertility, and since the direct application of fertilizers to the crop is attended 

 with considerable uncertainty, the most feasible method is to bring the soil up to the 

 proper condition by enriching the land for previous crops. The bestcroji of ]>otatoes 

 that has been grown at the station succeeded a crop of cabbages that had been heavily 

 manured. The most approved practice is to grow ijotatoes after clover, fertilizing 

 both the clover and preceding crop. 



Cutting of seed (pp. 13, 14). — The experiments with different methods 

 of cutting seed potatoes, which have been carried on each season since 

 the organization of the station, were continued in 1889 on a larger 

 scale than formerly and with a greater number of varieties, the special 

 object being to test the validity of conclusions drawn from former 

 experiments. 



There is sufficient uniformity in the results of different seasons to warrant the fol- 

 lowing conclusions : 



(1) Other conditions being the same, the larger the cutting the greater the total 

 product, i. c. the total product varies in about the same ratio as the size of the cut- 

 ting. 



(2) The luarkctnblc product also increases as the size of the cutting is increased, 

 but does not follow the same ratio as th(^ total product, the rate of gain l)eing less. 



(:?) The increase is found in both the large and suiall potatoes, the greater porlion 

 being in the latter. 



(4) A crop growii from whole potatoes matun^s at an earlier date than from small 

 cuttings. 



