224 



COMPARISON BETWEEN VARIOUS ROTATION PEAS 



What is the value of these peas from the point of view 

 of the fixation of atmospheric nitrogen ? It is impossible to 

 attribute a greater value to any particular one more than 

 another; the conditions vary with every variety, and 

 numerous other factors enter into play and are the cause 

 of the same pea giving different results. 



It is observed that the proportion of nitrogen is higher 

 in some than in others, but when this element is stated in 

 terms of similar areas, provided the yields from these areas 

 are not considerably lower (such as those of the Lima bean 

 and pois dragees), the weights of nitrogen per hectare do 

 not vary within very wide limits. 



In the following table we have taken the average of the 

 figures from the four trials quoted in the first table as repre- 

 senting the average yield per arpent, and have calculated 

 the nitrogen per hectare on this basis. 



Nitrogenous matteu 



Without draw ing an\' comparisons between these different 

 peas it can, nevertheless, be seen that by ploughing in the 

 crop the total of nitrogen incorporated with the soil is very 

 high and constitutes a clear gain, since the larger portion is 

 derived from the atmosphere. Thus considerable advantage 

 is to be derived from the practice of crop rotation, and no 

 planter who is mindful of his interests should neglect an 

 opportunity of enriching his land every year by cultivating 

 suitable peas, either as a pure crop or in.terplanted with 

 canes. 



