CH. V] 



A Cultivation Experiment 



83 



now be provided with 25 fixed posts projecting from the 

 soil (Fig. 23). Lay a straight-edge from post to post 

 and measure with a ruler the depth of the surface below 

 it. The posts being fixed this straight-edge constitutes 

 a fixed base line from which the change in level of the 



i 



1 



1 



i 



Fig. 23. Plot of land witH fixed pegs for cultivation 

 experiments. (Mr Gumey's experiment.) 



soil can be determined at any time. Divide the plot into 

 two parts, leave one alone and dig the other deeply, 

 leaving the surface approximately level. The following 

 are some of the results obtained : 



Mean 

 62 inches 



3-^ :, 



Level of soil below straight-edge 



Before digging 6^ o| 6| 7 7 7 



After digging 4 3 3 3 3 4 



Raising of surface due to digging 



Readings should also be taken after a heavy down- 

 pour of rain, and after a good frost to show how these 

 affect the soil. 



Spring jultivation. The object of the spring cultiva- 

 tion is to complete the winter cultivation and obtain 

 a tilth ouitable to the crop. The operations depend on 



