376 EXPERIMENTS WITH FERTILISERS [chap. xiii. 



difficulty is increased by the way the leaf takes the eye, 

 so that a lighter but more leafy crop, due to a com- 

 parative excess of nitrogen, will generally be set down 

 as the heavier. 



In field experiments, as in all other applications of 

 science to agriculture, the problems involved are so 

 complex, the factors which intervene are so various and 

 unexpected, that the greatest rigour and technical 

 skill are called for in the conduct of the investigation, 

 to be followed by an even greater measure of scientific 

 caution in interpreting the results. 



