THE MONTHLY BULLETIN. 749 



made: (1) Kainit, 1,000 pounds per acre; (2) kainit, 1,500 pounds per acre; 

 (3) high-grade potassium sulphate, 667 pounds per acre; (4) high-grade potas- 

 sium sulphate. 1,33.3 pounds i)er acre; (fi) ammonium sulphate, 1,000 pounds 

 per acre; (6) muriate of potash, 1,000 pounds per acre; (7) potassium mag- 

 nesium carbonate, 667 pounds per a(.-re ; (8) potassium magnesium carbonate, 

 1,333 pounds per acre. The checks received no nurabei's in 1007. The plats 

 of that year and the checks were planted to tomatoes, okra, beans, and New 

 Era cowpeas, all of which are very susceptible to root-knot. The last year's 

 plats (1906 experiments) were also I'eplanted in 1907 with these four plants. 

 In 1906 the fertilizer plats were planted with New Era cowpeas and summer 

 squashes. To all of the fields was applied each year, at the rate of oOO pounds 

 per acre, a special brand of commercial fertilizer in common use in that vicinity, 

 the soil being so poor that without some comi^lete fertilizer nothing would grow 

 well. The experiments were intended to show the effect, if any, of an excess 

 of some particular fertilizer over the normal quantity applied. 



The 1906 plats showed plainly the beneficial effects of potash fertilizers on 

 the sandy soil of the experimental field. All the plats treated with kainit 

 and potassium sulphate were darker green and the plants were far more vigorous 

 than on the other plats. In fact, plats 12 and 15, respectively, kainit and 

 potassium sulphate, both 1,000 pounds to the aci'e, were so far as the cowpeas 

 were concerned, hard to excel anywhere. The squashes did not show much dif- 

 ference in any of the plats. They were badly infested with the squash bug, 

 which killed the plants out in some of the plats. The cowpeas in plat 12 showed 

 no nematodes and but few were present in the squashes. Plat 14 had a fair 

 amount of root-knot in the cowpeas and from few to many on the different 

 squash plants. The rest of the plats did not differ materially from the check 

 plats which were fairly badly affected, in spots very badly. 



The plants grown on these same plats in 1907 without the addition of the 

 fertilizers again were badly affected except in plat 12, and somewhat in plat 

 15, which remained fairly free, showing a residual effect. 



In the 1907 fertilizer experiments the following results were obtained. The 

 kainit applications were injurious to the germination of the seeds, both the 1.000 

 as well as the 1,500 pound application, but naturally the latter more markedly. 

 The amount of root-knot, however, in these plats was slight. Potassium sulphate 

 at 667 pounds per acre was not injurious, but at twice that amount it so injured 

 the germination of the cowpeas and beans that they required replanting. Root- 

 knot was fairly abundant and strangely, more so in the more highly fertilized 

 plat. In both plats the growth of the plants was very vigorous. The sulphate 

 of ammonia at the rate used exerted a very harmful effect on germination, requir- 

 ing several replantings. The plants that did grow, however, were very vigorous, 

 dark green, and rather free from nematodes. The muriate of potash injured 

 the germination of the beans and cowpeas, while the nematodes were fairly 

 abundant. The potassium magnesium carbonate gave the best and most vigorous 

 plants of all, without injury to germination. Root-knot was present in most of 

 the plants, but not abundant. 



Judging from these experiments, it is clear that fertilizers alone can not be 

 depended upon to exterminate root-knot. On the other hand it is also plain that 

 some fertilizers exert a beneficial effect upon the plant and enable it to make a 

 good crop in spite of nematodes. Perhaps they may also increase the resisting 

 power of the plant against the entrance of the nematodes into the roots. The 

 potash fertilizers seem to be most favorable for this purpose, so far as the experi- 

 ments at Monetta and observations elsewhere go. However, it will not be safe 

 to conclude that they will be equally beneficial everywhere. In the sandy, rather 

 potash-free soils of South Carolina and Florida the application of potash in 

 amoimts not too large seems to be followed by favorable results. 



According to Stift,^ Hollrung. in Germany, has shown that fertilizing highly 

 with potash alone is not of much benefit to beets attacked by the sugar-beet 

 nematode. Wimmer has shown that the nematodes remove the different minerals 

 almost equally, so that only where one element is rather deficient will the addi- 

 tion of that alone be of benefit. The sugar-beet nematode removes large quanti- 

 ties of mineral food from the roots, so that unless these minerals are present in 

 the soil in considerable excess over that naturally needed by the crop the plants 

 will suffer from lack of that mineral which is not sufficiently abundant. Thus, 

 an amount of potash sufficient for a healthy crop may be insufiicient if the sugar- 

 beet nematode is present, and the symptoms of potash hunger can be averted only 

 by applying an excess of potash. Probably thi;^ is also true of the root-knot 

 nematode. The sandy soils of South Carolina are rather potash poor, so that 

 a diseased plant will suffer from potash hunger, while the other elements may be 

 in sufficient abundance. At any rate, the addition of potash in excess proves 

 helpful. The nitrogen-containing fertilizers when not in too great excess also 

 benefited the plants somewhat, but not so markedly as the potash. This is to 

 be expected, as nitrogen is not any too abundant in those soils. The phosphatic 

 fertilizers, however, showed no benefit at all. 



<Stift, 1908. 



