EFFECT ON CLOVER OF LIMING THE SOIL. 123 



Variations in the percentages of ash in the roots were probably due in 

 part to the presence of clay, which could not be completely washed from 

 the roots. This was clearly indicated by the following experiment. Parallel 

 ash determinations were made on the roots from the unlimed half of plot 

 5 and those from the limed half of plot 7, which represented, respectively, 

 the maximum and minimum ash percentages. After weighing the total 

 ash it was dissolved in strong hj'drochloric acid, then diluted with water 

 and filtered. The insoluble residue on the filter was then ignited and 

 weighed. The soluble ash percentages were nearly ahke. 



The percentages of ash, iron oxide and calcium oxide throw no light 

 on the specific effect of hming the soil. There appears to be neither too 

 much iron nor too little calcium in the tissues of the plants from the un- 

 hmed areas, unless the small differences in the percentages from limed 

 and unUmed roots are sufficient to warrant such a deduction. 



The marked differences in the nitrogen percentages in the unhmed 

 crops when compared with those in the limed crops justify the deduction 

 that available nitrogen was an important factor in promoting the growth 

 of the plants. It is well known that carbonate of hme is beneficial to 

 bacterial development; therefore it is reasonable to conclude that fixa- 

 tion and nitrification of nitrogen have been accelerated on the limed 

 areas to the marked advantage of the plants, in comparison with those 

 on the unhmed areas. 



The increased formation of available nitrogen can be considered as 

 true even for the plots receiving nitrate of soda, because 45 pounds of 

 nitrogen would be completely used in 1,233 pounds of dry matter con- 

 taining an average of 3.65 per cent, of nitrogen, which is the average for 

 the crops from the limed halves of plots 1 and 2. That amount of dry 

 matter represents a small yield of clover hay per acre, to say nothing of 

 the roots of the crop, which contained 2.77 per cent, of nitrogen. In 

 this instance the clover was not harvested, and we have no weights to 

 confirm our opinion. 



Besides the lessened availability of the nitrogen on the unlimed halves 

 of the plots dressed with sulfate of ammonia there was also the probable 

 liindrance to root development due to the presence of sulfate of iron and 

 sulfate of aluminum, noted by Mr. Ruprecht in his work on the soils 

 from these plots. As already noted in the description of samples, the 

 roots obtained from the unlimed half of plot 5 were much smaller than 



