Cultivation aiid tillage 



The thermometer readings are in degrees centigrade. 



Remarks. June 20th : Hot suimj day, there had been no rain 

 since June 11th. 



June 27th : Cold, cloudy day, several cold, wet days during the 

 past week. 



On the cold day there was very little difference 

 between the plots, but on the hot day the hoed plots 

 were cooler than the others. Now only the top inch is 

 touched by the hoe, and so it appears that the layer 

 thus loosened shields the rest of the soil from the sun's 

 heat. If this is the case we ought to find that any 

 other loose material would act in just the same way. 

 We must, therefore, set out a fourth plot alongside the 

 others, cover it with straw or cut grass (a cover like this 

 is called a mulch), and take the temperature there. 

 Some of the results were as follows: — 



Ilemarks. Sept. 24th : Warm day after a rather cold spell. 

 Oct. 5th : After a long spell of dry, warm weather. 



The untouched plot had become smothered in weeds 

 and could no longer be used for this experiment. The 

 mulched soil is, however, cooler even than the hoed soil, 

 and our expectation that mulching would keep the soil 

 cool has turned out to be correct. 



