368 EXPERIMENTS WITH FERTILISERS [cHAP. 



are subject to no disturbance until they need renewing 

 through decay, and they afford sighting lines along 

 which lie the corners of the actual plots. Each of these 

 corners is marked by a stake or post of creosoted oak, 

 I foot long X 2\ inches square, sunk a foot below 

 the surface, so as to be out of the way of the plough or 

 any other cultivating tools. When the time comes for 

 setting out the plots before sowing the manures, the 

 operator measures off along the sighting line the known 

 distance to the corner of the first plot and then probes 

 the ground with a pointed steel rod until he finds the 

 buried post, above which he sets up a temporary but 

 sufficiently conspicuous stake. Proceeding in the same 

 way he marks the corners of all the plots, after which the 

 manures can be sown and the temporary stakes removed 

 before the manures are ploughed or harrowed in. As a 

 rule it is desirable to set out the plots with paths or 

 dividing strips between ; division strips are particularly 

 necessary on arable land to prevent the plough carrying 

 manured soil from one plot across on to the next. Paths 

 result in a stimulus, " the fallow effect," to the outside row 

 whether of corn or of roots ; consequently each plot 

 must be bordered by the same extent of path ; in some 

 respects it would be better to dispense with them, but 

 the necessity of studying the plots during growth, and 

 often of showing them to large numbers of people, 

 renders them indispensable. Whatever divisions are 

 adopted, it is better to sow the whole field and strike 

 out the paths afterwards by a hoe, care, of course, being 

 taken to start the drills each time at the same distance 

 from the edge of each plot. 



If the plots are continued year after year, it is 

 necessary to watch the method of ploughing; if a 

 turnwrest plough be used, the mould-board should be 

 set to throw the furrows opposite ways in alternate 



