FARMERS' INSTITUTES. 169 



the soil contains thirty to fifty per cent (according to the fineness of the 

 particles) of the quantity of water required for saturation, and there is 

 a very much slower movement of water from one particle to another." 

 And again he says, ''Capillary rise percolation of water in the soil, 

 declines as the water content of the soil diminishes." 



Now the water content of a soil, during seasons of drouth, such as we 

 have had for a series of years, has been reduced far below the 30 per cent 

 for sand or the 50 per cent for clay, and capillarity must have ceased its 

 action in the soil, long before a cultivated field began to suffer for want 

 of moisture. The physical conditions of soil in periods of drouth have 

 not been critically studied. Practical men, with keen observation, have 

 asked difficult questions of scientists, and they have answered in a super- 

 ficial sort of way, applying the explanation of a case that is no parallel 

 to the conditions in question. Farmers are not concerned about the 

 growth of their crops, when the soil contains even 18 per cent of moist- 

 ure. A water content above that will give them no great uneasiness; 

 nor are they particularly interested in the movements of water in the soil 

 at the saturation point. What they want to know is, will certain man- 

 ipulations of soil in times of extreme drouth favor the retention of water 

 in the soil, or induce it to gather there, and by what law is it controlled? 

 Every practical farmer will answer the first query in the aflSrmative; but 

 many hesitate to question nature, especially when the operation of its 

 laws are hid from sight. I lay no claim to scientific attainments. 1 am 

 perhaps an average observer, and intensely interested in what is going on 

 on my farm, and have studied the moisture problem for the last two sea- 

 sons with increasing interest. I believed at the beginning that explain- 

 ing the presence of moisture in cultivated soil by the law of capillary 

 attraction, was fallacious and unphilosophical, and that there was some 

 natural law by which it could be rationally -explained. I now believe 

 that vapor arising from the earth is condensed at the surface by a cool 

 stratum caused bv cultivation. 



DOBS CULTIVATION COOL THE SURFACE? 



Let us see. Corn has been known to be nipped by frost along freshly 

 cultivated rows, when the uncultivated corn remained uninjured. Straw- 

 berries which have been mulched (which is analogous to cultivation) suf- 

 fer from frost when contiguous rows, unmulched, remain unharmed. 

 Boards, lying on the ground, cool the surface, and we always find frost on 

 such boards if anywhere. These, I confess, are only pointers, which all, 

 or many, have observed. The thermometer test, however, is a better 

 one. Last July I made such a test. My pasture field adjoined the corn 

 field. In the one the grass was dried up and crisp, and in the other corn 

 was in tassel and ears appearing, and still fresh and growing from fre- 

 quent cultivation. I took a piece of inch and a half well pipe, 30 inches 

 long, and drove it two feet in the ground, into each field, near the 

 gate that opened between them. I then punched out the earth from the 

 lower end, so that the bulb of the thermometer should rest on the earth, 

 and tested the temperature every hour from 2 o'clock p. m. until sun- 

 down, both at the surface and at' the bottom of the tube, and at sunrise 

 22 



