LEGUMINOUS CROPS. 



133 



and possibly in part to percolation of the nitrifying organ- 

 isms, and the nitrification of the nitrogen of the sub-soil. 



Let us now compare the results relating to the Medicago 

 sativa with those relating to the Trifolium repens soils. 



TABLE 44. — Nitrogen as Nitric Acid per acre, lb., in the 

 Soil and Subsoils op some Experimental Plots, without 

 Nitrogenous Manure for more than 30 Years ; Hoosfield, 

 Rothamsted. Samples collected July 29 to August 14, 1885. 



SUMMARY AND CONTROL. 



The table of the estimated nitrogen in the produce per acre 

 (p. 128) shows that, from the commencement to 1885 inclu- 

 sive, the Trifolium repens yielded only 261 lb. of nitrogen in 

 crops, but that the Medicago gave 917 lb. Again, in 1885, 

 the year of soil-sampling, the Trifolium gave only 97 lb., but 

 the Medicago gave 270 lb. It is further to be observed that, 

 quite accordantly with the usual character of growth of 

 lucerne in agriculture, with the increasing root-range, and 

 consequently increased command of the stores of the soil and 

 subsoil, the yield of nitrogen increased from 28 lb. in the 

 first and second years, to 337 lb. in the fifth year of growth, 

 declining, however, somewhat afterwards. 



Under these circumstances of very large yields of nitrogen 

 in the crops, there is at every one of the twelve depths less, 



