144 MISSOURI AGRICULTURAL REPORT. 



fields. But they could see no necessary reason why the growing of clover 

 on a field and the removal of the crop from the ground should give to it 

 a higher productive power ; and so, except where there was some 

 other reason than that of improving the productive power of the field, 

 there was no incentive to grow regularly in the system of rotation some 

 one or another of the leguminous crops, like the clovers, alfalfa, lupine, 

 cow peas, soy beans or sainfoin. For a long time it was held that the 

 exclusive source of nitrogen for the higher plants was the organic matter 

 of the soil, and this, too, notwithstanding the fact that it was continually 

 being washed from the soil in the form of very soluble nitrates and 

 carried to the sea and even escaping in large quantities into the at- 

 mosphere in the form of free nitrogen. When, finally, the matter came 

 under rigid investigation by men of science, there followed a battle 

 •extending over years during which the opponents in the fray hurled 

 against one another all the weight of experimental evidence, cogency 

 of logic and massiveness of personal authority which they could com- 

 mand and there was a stage in the combat when it looked as though 

 error would be securely seated on the throne of truth, when this con- 

 viction of many practical men would be relegated to the category of 

 planting and butchering in the right phase of the moon. Indeed, it 

 was true that the highest authorities of the time and the most careful 

 and rigid experimenter, thinking and planning from a mistaken point 

 of view, the more cautiously they moved and the more thoroughly they 

 safeguarded their lines of attack to avoid the introduction of sources 

 of error, the more unquestionably did their results appear to bear out 

 the conviction, at that time thoroughly rooted, that none of the or- 

 dinary higher plants are able to add to their nitrogen supply from the 

 air itself. But in the many repetitions of experiments which were con- 

 ducted, particularly among tho.se which, it was held by opponents, did 

 not sufficiently guard against sources of error, there were found gains 

 of nitrogen, and these led to looking at the problem from different 

 points of view ; and, while the conflict with its story was long, the real 

 truth was finally brought into the light and we now know with the 

 dcfiniteness that twice two makes four that when a vigorous legum- 

 inous crop is matured upon the ground the soil is made absolutely richer 

 by the addition of very considerable amounts of nitrogen extracted 

 from the soil air by the microscopic organisms dwelling and feeding 

 in the tubercles or nodules found on the roots of the vigorous plants 

 of most, if not all, of the lar>;e clov.r-p.a-vetch-bean family. And 

 now that this great principle or method of adding the indispensable 

 nitrogen to the soil has been demonstrated with absoluteness, farmers 

 are able to proceed with the assurance of certainty rather than that 



