195 



sions did not seem necessary for the production of root tubercles. A 

 j^lausible supjiosition is that tlie micro-organisms or their spores were 

 floatin<r in the air and were deposited in the pots in Avhich the phmts 

 grew. 



"(6) As a rule, the greater the abundance of root tubercles in these 

 experiments, the larger and more vigorous were the plants and the 

 greater was the gain of nitrogen from the air. 



"(7) In a number of these experiments, as in similar ones previ- 

 ously reported, there was a loss of nitrogen instead of gain. The loss 

 occurrecl where there were no root tubercles; it was especially large 

 with oat ])lants, and largest where they had the most nitrogen at their 

 disposal in the form of nitrates. As the gain of nitrogen by the leg- 

 umes helps to explain why they act as ' renovating crops,' the loss in 

 the case of the oats suggests a possible reason why they should appear 

 to be an exhaustive crop. 



'"'Pract'aaJ inferences. — The ability of legmnes to gather nitrogen 

 from the air helps to explain the usefulness of clover, alfalfa, peas, 

 beans, vetches, and cowpeas as renovating crops, and enforces the 

 importance of using these crops to restore fertility to exhausted soils. 

 The judicious use of mineral fertilizers (containing phosphoric acid, 

 potash, and lime) will enable the farmer to grow crops of legumes, 

 which after being fed to his stock will, Avith proper care to collect and 

 preserve all manure. l)oth liquid and solid, enable him to return a 

 ' complete fertilizer " in the shaj^e of barnyard manure to his land. 

 A further advantage of growing these crops is that the nitrogenous 

 material, protein, which they contain in such great abundance is 

 especially valuable for fodder." 



Metkokolocjkal oiiSERVATioxs, E. A. Bailey (p. 19). — Summary 

 of observations from July 1 to September 30, 1S89. 



The Delaware Colleg-e Agricultural Experiment Station. 



Dcinirtiticiit of Drlairarc CoUcgc. 



Location. Newark. Director. Arthur T. Neale, I'b. D. 



BULLETIN No. G. OCTOBER. 1880. 

 Su.AniARY or THE Station's EXPEuniENTS ox the black rot of 

 GRAPES, A. T. Xeale, Ph. D. (pp. 3-()). — Experiments with Bordeaux 

 mixture for tliis disease on the vineA'ard of Mr. Anthony, of Smyrna, 

 Del., resulted in a saving estimated at $f55.G'2 per acre. The results of 

 experiments in Dr. Black's vineyard in Newcastle County, while 

 agreeing in the main with those at Smyrna, brought out the addi- 

 tional fact that the Bordeaux mixture may sometimes be used without 

 appreciable ell'ect. It should l)e observed, however, that in the former 

 case the mixture contained 1 pound of sulphate of copper to eight 

 vines; in the latter, the same amount to four vines. It was shown by 

 experiments at Smyrna that grapes spotted with a greenish-blue crust 



