652 Field Experiments on the Fixation of Free Nitrogen. 
1 was singularly unfortunate in tlie choice of the land, and 
hav'e given myself unnecessary trouble by making use of an 
area very difficult to work. The land was conveniently near to 
my house, and it once formed part of a wood covered with oak 
trees, from which oak and hazel underwood had been grubbed 
and the land roughly grassed. I had merel}^ the satisfaction of 
knowing that it had never been cultivated, had never received 
any manure, and was exceedingly poor — which was a virtue in 
this case. The soil, to a depth varying from ten to twenty 
inches, was a clay loam with veiy little organic matter in it, 
and rested on pure Oxford Clay. It was very well drained. 
The land contained the seeds of wild plants which continually 
came into growth ; and it yearly gives in places a good crop of 
bluebell. Even when cultivated it grew very poor grass crops, 
but, as I shall show, it would grow fair crops of red clover. 
The four plots which are specially under consideration are, like 
all the other plots, each of ten yai’ds long by ten yards wide, 
and are separated from each other by grass paths three feet wide. 
These four plots were marked for “ No Manure,” that is, they 
were intended to be cai’ried on with tillages only, no kind of 
manure to be used. At the time I instituted the plots I had no 
very fixed idea as regards the cropping I intended to follow ; 
generally, it was to embrace a series of experimental rotations. 
The four plots were, as nearly as possible, very much alike 
in colour and texture, and to a depth of twenty inches the soil 
was reddish, showing the iron to be in the state of peroxide. 
The subsoil was a pure clay, of dirty greenish-white colour, with 
streaks of red. 
I should have done much better had I profited by the ex- 
perience of Rothamsted, and chosen old farm land wliich had 
been agriculturally exhausted by continuous cropping with- 
out manure. Anyone undertaking in this country experiments 
in agriculture turns naturally to our great school at Rothamsted, 
and to the papers published by its eminent investigators Sir 
John Lawes and Dr. Gilbert. With Rothamsted I am well 
acquainted, and have carefully studied all the memoirs that have 
emanated therefrom since its establishment as an experimental 
station. In a certain sense it is somewhat disheartening for an 
intending experimenter to study these papers, with their care- 
fully drawn tables showing an amount of labour, skill, and 
perseverance that few men could hope to rival. However, my 
ambitions were not in the same direction, and, as I said before, mj’ 
object was of a more jjrivate and restricted character. What has 
struck me as so immensely meritorious in the Rothamsted work 
is the minuteness of the records and their evident trustworthi- 
